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Who cares about this crap?

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The patient who's tooth has just split sure wishes
he took 15 minutes out of a busy life to get
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Joel
 
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 #1    Today, 07:07 AM  
Joel344  
Member   Join Date: Oct 2004
Posts: 3,075  

Comparing Dental Literature with Medical Literature

--------------------------------------------------------------------------------

How come the dental articles are nowhere
to be found? Oh I get it, they want to
SELL us the information!

Compare this with,

"Echocardiography in chronic aortic insufficiency,"
which reveals what I want to know in a few
minutes and FREE of course!

If dentistry is a profession then why not
publish how many root canal, post, and
crown-treated teeth split within three years?

That could be useful for treatment planning
RCT or implant. Basically, in dentistry, we
just do not know ,,, because NO ONE besides
Sue and ME wants to know.

Joel

**

http://circ.ahajournals.org/cgi/con...stract/67/1/216

Circulation, Vol 67, 216-221, Copyright © 1983 by American Heart
Association

--------------------------------------------------------------------------------

ARTICLES

Echocardiography in chronic aortic insufficiency. Is valve replacement
too late when left ventricular end-systolic dimension reaches 55 mm?
P Fioretti, J Roelandt, RJ Bos, RS Meltzer, D van Hoogenhuijze, PW
Serruys, J Nauta and PG Hugenholtz

To determine whether a ventricular (LV) end-systolic dimension (ESD)
greater than or equal to 55 mm and LV left fractional shortening less
than 25% are risk factors for aortic valve replacement (AVR) in
patients with aortic insufficiency, we analyzed the clinical course
and M-mode echocardiograms in 47 consecutive patients who underwent
AVR for isolated symptomatic AI. Group 1 patients (n = 27) had a
preoperative ESD less than 55 mm (mean 44 mm, range 30-52 mm) and
group 2 patients (n = 20) had a preoperative ESD greater than or equal
to 55 mm (mean 62 mm, range 55-85 mm). One patient in group 1 and 10
patients in group 2 had left ventricular fractional shortening less
than 25%. There were no perioperative or postoperative deaths during
an average follow-up of 41 months (range 6-76 months). Five patients
had perioperative myocardial infarctions (MIs), three in group 1 and
two in group 2. Since myocardial protection with cold potassium
cardioplegia was instituted, no patient has suffered a perioperative
MI. The average preoperative New York Heart Association functional
classification was 2.3 (group 1) and 2.6 (group 2). Postoperatively,
it was 1.2 in group 1 and 1.1 in group 2. Thirty-three patients (20 in
group 1 and 13 in group 2) had echocardiograms at least 1 year after
AVR. Of these, LV-end diastolic dimension decreased fro 67 +/- 6 to 53
+/- 6 mm (mean +/- SD) in group 1 (p less than 0.001) and from 79 +/-
3 to 55 +/- 6 mm in group 2 (p less than 0.001). The LVESD also
decreased, but this is difficult to interpret because of frequent
postoperative abnormal interventricular septal motion. The LV
cross-sectional area, an index of LV mass, decreased in group 1 from
25 +/- 5 to 20 +/- 5 cm2 (p lss than 0.001) and in group 2 from 32 +/-
9 to 20 +/- 5 cm2 (p less than 0.001). Postoperative end-diastolic
dimension and cross-sectional area were not significantly different
between the two groups. We concluded that in aortic insufficiency, a
preoperative ESD greater than or equal to 55 mm does not preclude
successful AVR, as judged by long-term survival, symptomatic relief,
and normalization of LV dimensions assessed by echocardiography.

This article has been cited by other articles:

Y. Misawa, K. Fuse, H. P. Chaliki, D. Mohty, J.-F. Avierinos, A. J.
Tajik, M. Enriquez-Sarano, C. G. Scott, and H. V. Schaff
Left Ventricular Remodeling After Valve Replacement in Patients With
Isolated Aortic Regurgitation * Response
Circulation, June 10, 2003; 107(22): e208 - 209.
[Full Text] [PDF]

--------------------------------------------------------------------------------

H. P. Chaliki, D. Mohty, J.-F. Avierinos, C. G. Scott, H. V. Schaff,
A. J. Tajik, and M. Enriquez-Sarano
Outcomes After Aortic Valve Replacement in Patients With Severe Aortic
Regurgitation and Markedly Reduced Left Ventricular Function
Circulation, November 19, 2002; 106(21): 2687 - 2693.
[Abstract] [Full Text] [PDF]

--------------------------------------------------------------------------------

E. Klodas, M. Enriquez-Sarano, A. J. Tajik, C. J. Mullany, K. R.
Bailey, and J. B. Seward
Surgery for Aortic Regurgitation in Women: Contrasting Indications and
Outcomes Compared With Men
Circulation, November 15, 1996; 94(10): 2472 - 2478.
[Abstract] [Full Text]

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S Wahi, B Haluska, A Pasquet, C Case, C M Rimmerman, and T H Marwick
Exercise echocardiography predicts development of left ventricular
dysfunction in medically and surgically treated patients with
asymptomatic severe aortic regurgitation
Heart, December 1, 2000; 84(6): 606 - 614.
[Abstract] [Full Text]

--------------------------------------------------------------------------------

K. S. Dujardin, M. Enriquez-Sarano, H. V. Schaff, K. R. Bailey, J. B.
Seward, and A. J. Tajik
Mortality and Morbidity of Aortic Regurgitation in Clinical Practice :
A Long-Term Follow-Up Study
Circulation, April 13, 1999; 99(14): 1851 - 1857.
[Abstract] [Full Text] [PDF]

--------------------------------------------------------------------------------

&***

http://heart.bmjjournals.com/cgi/co...stract/84/6/606

Heart 2000;84:606-614 ( December )
Cardiovascular medicine

Exercise echocardiography predicts development of left ventricular
dysfunction in medically and surgically treated patients with
asymptomatic severe aortic regurgitation
S Wahib, B Haluskab, A Pasqueta, C Caseb, C M Rimmermana, T H Marwickb
a Cleveland Clinic Foundation, Cleveland, Ohio, USA, b University
Department of Medicine, University of Queensland, Princess Alexandra
Hospital, Ipswich Road, Brisbane, Qld 4102, Australia

Correspondence to: Dr Marwick tmarwick@medicine.pa.uq.edu.au

Accepted 17 July 2000

OBJECTIVETo assess resting and exercise echocardiography for
prediction of left ventricular dysfunction in patients with
significant asymptomatic aortic regurgitation.
DESIGNCohort study of patients with aortic regurgitation.
SETTINGTertiary referral centre specialising in valvar surgery.
PATIENTS61 patients (38 men, 23 women; mean (SD) age 53 (14) years)
with asymptomatic or minimally symptomatic aortic regurgitation and no
known coronary artery disease; 35 were treated medically and 26 had
aortic valve replacement.
INTERVENTIONSExercise echocardiography was used to evaluate ejection
fraction, which was measured on the resting and post-stress images
using the modified Simpson method. Patients with an increment of
ejection fraction after exercise were denoted as having contractile
reserve (CR+); those without an increment were labelled CR.
MAIN OUTCOME MEASURESStandard univariate and multivariate methods and
receiver operating characteristic analyses were used to assess the
ability of contractile reserve to predict follow up ejection fraction.
RESULTSIn the 35 medically treated patients, 13 of 21 (62%) with CR+
(mean (SD) ejection fraction increment 7 (3)%) had preserved ejection
fraction on follow up. In the 14 patients with CR (ejection fraction
decrement 8 (4)%), 13 (93%) had a decrement of ejection fraction on
follow up from 60 (5)% at baseline to 54 (3)% on follow up (p =
0.005). Age, resting left ventricular dimensions, medical treatment,
aortic regurgitation severity, exercise capacity, and rate-pressure
product were similar in both CR+ and CR groups. Among the 26 surgical
patients, 13 showed CR+ (ejection fraction increase 9 (5)%), all of
whom had an increase in ejection fraction on follow up (from 49% to
59%). Of 13 surgical patients with CR (ejection fraction decrease 7
(5)%), 10 (77%) showed the same or worse ejection fraction on
postoperative follow up.
CONCLUSIONSContractile reserve on exercise echocardiography is a
better predictor of left ventricular decompensation than resting
indices in asymptomatic patients with aortic regurgitation. In
patients undergoing aortic valve replacement, contractile reserve had
a better correlation with resting ejection fraction on postoperative
follow up. Measurement of contractile reserve may be useful to monitor
the early development of myocardial dysfunction in asymptomatic
patients with aortic regurgitation, and may help to optimise the
timing of surgery.

Keywords: aortic regurgitation; contractile reserve; exercise testing;
ejection fraction

--------------------------------------------------------------------------------
© 2000 by Heart

This article has been cited by other articles:

M. Rothenburger, K. Drebber, T. D.T. Tjan, C. Schmidt, C. Schmid, T.
Wichter, H. H. Scheld, and M. Deiwick
Aortic valve replacement for aortic regurgitation and stenosis, in
patients with severe left ventricular dysfunction
Eur. J. Cardiothorac. Surg., May 1, 2003; 23(5): 703 - 709.
[Abstract] [Full Text] [PDF]

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS

FULL

http://heart.bmjjournals.com/cgi/content/full/84/6/606

Heart 2000;84:606-614 ( December )
Cardiovascular medicine

Exercise echocardiography predicts development of left ventricular
dysfunction in medically and surgically treated patients with
asymptomatic severe aortic regurgitation
S Wahib, B Haluskab, A Pasqueta, C Caseb, C M Rimmermana, T H Marwickb
a Cleveland Clinic Foundation, Cleveland, Ohio, USA, b University
Department of Medicine, University of Queensland, Princess Alexandra
Hospital, Ipswich Road, Brisbane, Qld 4102, Australia

Correspondence to: Dr Marwick tmarwick@medicine.pa.uq.edu.au

Accepted 17 July 2000

Abstract
Top
Abstract
Introduction
Methods
Results
Discussion
References
OBJECTIVETo assess resting and exercise echocardiography for
prediction of left ventricular dysfunction in patients with
significant asymptomatic aortic regurgitation.
DESIGNCohort study of patients with aortic regurgitation.
SETTINGTertiary referral centre specialising in valvar surgery.
PATIENTS61 patients (38 men, 23 women; mean (SD) age 53 (14) years)
with asymptomatic or minimally symptomatic aortic regurgitation and no
known coronary artery disease; 35 were treated medically and 26 had
aortic valve replacement.
INTERVENTIONSExercise echocardiography was used to evaluate ejection
fraction, which was measured on the resting and post-stress images
using the modified Simpson method. Patients with an increment of
ejection fraction after exercise were denoted as having contractile
reserve (CR+); those without an increment were labelled CR.
MAIN OUTCOME MEASURESStandard univariate and multivariate methods and
receiver operating characteristic analyses were used to assess the
ability of contractile reserve to predict follow up ejection fraction.
RESULTSIn the 35 medically treated patients, 13 of 21 (62%) with CR+
(mean (SD) ejection fraction increment 7 (3)%) had preserved ejection
fraction on follow up. In the 14 patients with CR (ejection fraction
decrement 8 (4)%), 13 (93%) had a decrement of ejection fraction on
follow up from 60 (5)% at baseline to 54 (3)% on follow up (p =
0.005). Age, resting left ventricular dimensions, medical treatment,
aortic regurgitation severity, exercise capacity, and rate-pressure
product were similar in both CR+ and CR groups. Among the 26 surgical
patients, 13 showed CR+ (ejection fraction increase 9 (5)%), all of
whom had an increase in ejection fraction on follow up (from 49% to
59%). Of 13 surgical patients with CR (ejection fraction decrease 7
(5)%), 10 (77%) showed the same or worse ejection fraction on
postoperative follow up.
CONCLUSIONSContractile reserve on exercise echocardiography is a
better predictor of left ventricular decompensation than resting
indices in asymptomatic patients with aortic regurgitation. In
patients undergoing aortic valve replacement, contractile reserve had
a better correlation with resting ejection fraction on postoperative
follow up. Measurement of contractile reserve may be useful to monitor
the early development of myocardial dysfunction in asymptomatic
patients with aortic regurgitation, and may help to optimise the
timing of surgery.
(Heart 2000;84:606-614)

Keywords: aortic regurgitation; contractile reserve; exercise testing;
ejection fraction

Introduction
Top
Abstract
Introduction
Methods
Results
Discussion
References
Volume overload from aortic regurgitation is usually well tolerated by
the left ventricle early in the course of the disease. The development
of symptoms occurs later and implies left ventricular decompensation.1
2 Aortic valve replacement is commonly recommended while the patient
is still asymptomatic, but selection of the optimum time for surgery
may be difficult. Although early surgery has been proposed,3 4 valve
replacement carries a 1-3% operative mortality and the ongoing risks
of a prosthetic valve warrant consideration as aortic valve repair is
rarely feasible. However, left ventricular function is a major
determinant of long term prognosis,3 and excessive delay before
surgery can result in compromised long term survival owing to
significant myocardial damage and the development of left ventricular
dysfunction.4-6 The ability to predict left ventricular dysfunction
during follow up could have important implications for the timing of
intervention.7

Several studies have examined the outcome of medical and surgical
treatment in patients with aortic regurgitation, most of which have
focused on symptomatic patients with overt left ventricular
dysfunction.5 8 9 The presence of preoperative left ventricular
dysfunction (left ventricular systolic dimension > 55 mm and
fractional shortening < 25%) is significantly related to the risk of
the developing chronic heart failure and to mortality.5 Other criteria
involving left ventricular dimensions and resting indices of left
ventricular function have been shown to predict outcome,5 10-12 but
various investigators have argued that these are either too
restrictive or too liberal,13-15 and the guidelines for intervention
in asymptomatic patients are not universally accepted.

Previous work with radionuclide ventriculography has shown that the
ejection fraction during exercise and the change from rest to stress
to be abnormal in many patients with aortic regurgitation,16-18 and
these data may be predictive of outcome.18 Echocardiography is a more
widely available technique, and exercise echocardiographic measurement
of ejection fraction and end systolic volume has been shown to predict
outcome in patients with mitral regurgitation.19 However, there are
limited data to support its use in aortic regurgitation,20 and in the
most recent guidelines for the management of patients with valvar
heart disease21 this technique was given a class III indication
(evidence or general agreement that the procedure is not useful). In
this study, we sought to determine whether exercise echocardiography
might be used to predict left ventricular dysfunction during follow up
of patients with significant asymptomatic aortic regurgitation.

Methods
Top
Abstract
Introduction
Methods
Results
Discussion
References
STUDY PATIENTS
We prospectively studied 61 patients (38 men, 23 women; mean (SD) age
53 (14) years) with asymptomatic or minimally symptomatic severe
aortic regurgitation. These patients were selected from a larger
population referred to the Cleveland Clinic Foundation for evaluation
of chronic aortic regurgitation and potential valve surgery. From this
larger group, those with clear indications for valve replacement
proceeded to surgery. These patients had symptoms (mainly exercise
intolerance), severe left ventricular enlargement (left ventricular
systolic dimension > 55 mm or volume > 60 ml/m2), or left ventricular
dysfunction (ejection fraction < 50%).21 The remaining patients with
severe aortic regurgitation (grade 3/4 or 4/4) in the absence of
symptoms or echocardiographic indications for intervention were
recruited into the study.

Patients with previous cardiac surgery, coexisting mitral valve
disease, more than mild aortic stenosis, and suboptimal images were
excluded. Patients with a history of angina, previous acute myocardial
infarction, coronary artery bypass grafting, or known coronary artery
disease on angiography were excluded, in order to minimise additional
factors that may affect left ventricular function. Although images
were of variable quality, no patient was excluded because of
suboptimal images.

The aetiology of aortic regurgitation included congenital bicuspid
aortic valve, rheumatic valvar disease, sclerodegenerative disease,
and aortic annular dilatation.

BASELINE RESTING AND EXERCISE ECHOCARDIOGRAPHY
All patients underwent transthoracic echocardiography in the left
lateral decubitus position at rest and immediately after exercise.
Imaging was performed with standard commercially available equipment
and digitised on-line into a quad screen, cineloop format (ImageVue,
Kodak Health Imaging, Allendale, New Jersey, USA). Images were also
recorded on half inch VHS videotape. Resting left ventricular end
diastolic and end systolic dimensions and the thickness of the
interventricular septum and posterior wall were measured. The severity
of the aortic regurgitation was assessed semiquantitatively by colour
and continuous wave Doppler by expert echocardiographers independent
of the investigators, using a combination of colour jet dimensions,
pressure half time, and aortic flow reversal.22-24 Left ventricular
end diastolic and end systolic volumes were measured from the apical
four chamber view, by an experienced observer using the modified
Simpson rule. Only representative cycles were measured and the average
of three measurements was taken. The endocardial border was traced,
excluding the papillary muscles. The frame captured at the R wave of
the ECG was considered to be the end diastolic frame, and the frame
with the smallest left ventricular cavity, the end systolic frame.
Ejection fraction was calculated from the difference between the end
diastolic and end systolic volumes, at rest and immediately after
exercise. The difference between the resting and postexercise ejection
fraction was defined as the contractile reserve (CR). Patients with an
augmentation of ejection fraction with exercise were designated as
having contractile reserve (CR+), and those failing to augment were
identified as CR.

We have previously shown a mean (SD) intraobserver variability for the
recording of resting ejection fraction of 2 (4)%, and of left
ventricular end diastolic and end systolic volumes of 5 (10) ml (r =
0.97) and 1 (4) ml (r = 0.99), respectively. After exercise, the
respective variabilities were 1 (2)%, 1 (10) ml (r = 0.98), and 1 (3)
ml (r = 0.99). Values for interobserver variability were comparable.19

The 12 lead ECG was performed, using conventional chest lead
positioning, before exercise, at the conclusion of each stage, and
after stress. Symptom limited treadmill exercise testing was performed
in all patients, using a protocol selected according to the
cardiovascular and overall physical state of each subject (Bruce,
modified Bruce, or Naughton). Blood pressure and the physical signs
were monitored during exercise testing in the usual fashion, and the
conventional end points for exercise testing were applied.25 Peak
heart rate, blood pressure, rate-pressure product, and estimated
exercise capacity were recorded for all patients. All but five
patients in the medically treated group achieved 85% of their age
predicted maximum heart rate with exercise.

FOLLOW UP
Thirty five patients (19 men, 16 women; mean (SD) age 51 (15) years)
proceeded with medical treatment selected by the physician caring for
the patient; these included 28 patients (80%) in functional class I
and seven (20%) in functional class II at the time of inclusion into
the study.

The surgical group comprised 26 patients with significant aortic
regurgitation who underwent aortic valve replacement within 3 (2)
months of their exercise stress test. This clinical decision was made
by the treating physician, based on progression of the disease and
independent of the study. In most patients this reflected the interim
development of symptoms, but included increasing left ventricular
systolic dimension (to > 55 mm) and volume (to > 60 ml/m2), and
falling ejection fraction (to < 50%) on serial studies.21

A resting transthoracic echocardiogram was repeated and recorded (as
described for the baseline study) at the end of the follow up period.
The follow up ejection fraction was compared with their baseline
ejection fraction in order to identify any change in left ventricular
function.

STATISTICAL ANALYSIS
In both the medically treated group and the patients undergoing an
aortic valve replacement, the results were examined in two different
analyses. First, according to the change in ejection fraction induced
by exercise, patients were grouped as those with preserved or impaired
contractile reserve. Second, comparing their follow up ejection
fraction with that at baseline, patients were grouped as those in whom
the ejection fraction had decreased or remained steady/improved when
compared with baseline. Results are expressed as mean (SD) unless
stated otherwise. The 2 test was used to compare categorical variables
and the paired or unpaired Student t test to compare continuous
variables. Spearman's correlation coefficient was used to estimate the
correlation between continuous variables. Multiple linear regression
models were developed to examine the independent predictors of global
left ventricular function over follow up. Receiver operating
characteristic (ROC) curves were used to evaluate various levels of
contractile reserve for the prediction of left ventricular function
over follow up. Significance was defined as a value of p < 0.05.

Results
Top
Abstract
Introduction
Methods
Results
Discussion
References
CLINICAL CHARACTERISTICS
Table 1 summarises the clinical characteristics of medically and
surgically treated patients, subdivided into those with and those
without contractile reserve. Patients were not systematically given
medical treatment; any treatments given were based on the presence of
symptoms. Those undergoing valve replacement had more severe aortic
regurgitation but were otherwise comparable to those treated
medically.

View this table:
[in this window]
[in a new window]
Table 1 Clinical characteristics of patients with (CR+) and without
(CR) contractile reserve. No significant differences were present
between CR+ and CR groups

In the medically treated group, 21 of the 35 patients in the study
(60%) increased their ejection fraction with exercise, signifying
intact contractile reserve (CR+), whereas 14 (40%) lacked contractile
reserve (CR; decrease or no change in their ejection fraction). In the
patients undergoing aortic valve replacement, the contractile reserve
was preserved in 13 (50%) of the 26 patients and lacking in the other
half of the group. Patients with and without contractile reserve were
comparable on clinical grounds.

BASELINE ECHOCARDIOGRAPHY
The resting and exercise left ventricular dimensions and exercise
responses of medically treated patients with and without contractile
reserve are listed in table 2A, and equivalent data for those who
underwent aortic valve replacement are given in table 2B. Patients
with contractile reserve were characterised by a reduction in end
systolic volume, which produced an increment of the ejection fraction.
Patients in the CR+ subset showed a 9% decrease in end diastolic
volume in both the medical and surgical groups. This was similar to a
10% decrease in the end diastolic volume both medical and surgical
groups in the CR subset (NS). However, the end systolic volume in the
CR+ subset decreased by 23% and 24% in the medical and surgical
groups, respectively, whereas there was a 9% and 4% increase in the
end systolic volume in the respective medical and surgical subsets of
the CR patients (both p < 0.0001). Thus the postexercise ejection
fraction increased by 7 (3)% and 9 (2)% in the medical and surgical
CR+ subsets, whereas the CR subset had an 8 (3)% and a 7 (2)% decrease
in medical and surgical patients (p = 0.001). All other aspects of
exercise characteristics were comparable in the two groups;
specifically, there were no significant differences in exercise
capacity or conventional indices of left ventricular function.

View this table:
[in this window]
[in a new window]
Table 2 Rest and exercise measurements in patients with (CR+) and
without (CR) contractile reserve)

FOLLOW UP OF PATIENTS ON MEDICAL TREATMENT
None of the medically treated patients developed a significant change
in functional status or underwent surgery during the mean follow up
period of 15 (7) months. On follow up cross sectional
echocardiography, there were 14 patients (40%) whose ejection fraction
was unchanged from the baseline and 21 (60%) who showed a
deterioration. Latent left ventricular dysfunction was identified
retrospectively by the finding of a reduction in resting ejection
fraction on follow up compared with baseline function.

The baseline clinical and exercise characteristics and resting left
ventricular dimensions were comparable in patients with and without a
change of ejection fraction on follow up (table 3). However, the
contractile reserve at baseline correlated with the change in ejection
fraction on follow up (fig 1A). When the contractile reserve on
exercise was examined as a categorical variable to predict a change in
the ejection fraction (table 4), of the 21 patients with a positive
contractile reserve at baseline, 13 had a preserved ejection fraction
at follow up. On the other hand, of the 14 patients with a negative
contractile reserve on exercise at baseline, 13 showed a significant
decrease in ejection fraction on follow up (2 = 10.5, p = 0.001).

View this table:
[in this window]
[in a new window]
Table 3 Baseline characteristics of groups with maintained or
increased (EF+) and decreased (EF) ejection fraction on follow up on
medical treatment

View larger version (12K):
[in this window]
[in a new window]
Figure 1 Correlation of contractile reserve with change of ejection
fraction (EF) over follow up in patients treated medically (A) or with
valve replacement (B).

View this table:
[in this window]
[in a new window]
Table 4 Relation between change in ejection fraction on follow up on
medical treatment and contractile reserve at baseline

These changes in ejection fraction were unrelated to changes in end
diastolic volume with exercise; patients who maintained their ejection
fraction on follow up showed a 17 cm3 (9%) decrease in the mean end
diastolic volume, similar to a 12 cm3 (9%) decrease in the group with
the latent left ventricular dysfunction (NS). However, the
postexercise end systolic volume in the maintained ejection fraction
group decreased by 23% compared with a 2% increase in end systolic
volume in the latent left ventricular dysfunction group (p < 0.01).
The group with maintained ejection fraction had a positive contractile
reserve of 7 (4)% with exercise at baseline, while the group with the
latent left ventricular dysfunction had a negative contractile reserve
of 3 (8)% with exercise at baseline (p < 0.001).

Figure 2 shows the responses of end systolic volume to exercise and
follow up in individual patients. Patients with maintained ejection
fraction on follow up (fig 2A) showed a significant decrease in the
mean end systolic volume with exercise at the baseline study. No
difference in the resting end systolic volume at baseline and follow
up was observed, suggesting well preserved left ventricular systolic
function. On the other hand, patients whose ejection fraction
deteriorated during follow up (fig 2B) showed no augmentation in their
end systolic volume with exercise, and had a significant increase in
their resting end systolic volume on follow up.

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[in this window]
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Figure 2 Change in left ventricular end systolic volume (ESV) with
exercise (Ex) and on follow up (F/U) compared with baseline at rest
(R), in patients with maintained left ventricular function (A) and
latent dysfunction (B).

Figure 3A compares the accuracy of change in end systolic volume with
exercise and the contractile reserve for prediction of the change in
ejection fraction on follow up in medically treated patients.
Contractile reserve was slightly more sensitive (64%) compared with
change in end systolic volume (43%). Both had a similar high
specificity of 93%. Thus contractile reserve had a marginally better
accuracy (74% v 64%) for predicting preserved left ventricular
function than change in end systolic volume alone with exercise (NS).
The ROC curve in fig 4A shows the sensitivity and specificity of
contractile reserve for predicting change in left ventricular ejection
fraction on follow up. At the optimal cut off (contractile reserve
4%), the sensitivity and specificity of predicting subsequent left
ventricular dysfunction were both 77%.

View larger version (14K):
[in this window]
[in a new window]
Figure 3 Accuracy of contractile reserve (CR) and change in end
systolic volume (ESV) with exercise as predictors of follow up
ejection fraction, in patients followed up on medical treatment (A)
and undergoing an aortic valve replacement (B).

View larger version (20K):
[in this window]
[in a new window]
Figure 4 Receiver operating characteristic curves relating levels of
contractile reserve to sensitivity and specificity for predicting left
ventricular dysfunction at follow up in patients treated medically (A)
and with valve replacement (B).

FOLLOW UP OF PATIENTS UNDERGOING AORTIC VALVE REPLACEMENT
Patients undergoing aortic valve replacement were reassessed by
transthoracic echocardiography after a mean follow up of 6 (8) months.
Sixteen patients (62%) showed an improvement of ejection fraction and
10 patients (38%) showed a reduction of ejection fraction after
surgery. There were no significant differences in the baseline
clinical and exercise characteristics or in resting left ventricular
dimensions in patients with and without a change of ejection fraction
on follow up (table 5).

View this table:
[in this window]
[in a new window]
Table 5 Baseline characteristics of groups with maintained or
increased (EF+) and decreased (EF) ejection fraction on follow up
after aortic valve replacement

Changes in ejection fraction during follow up in patients who
underwent valve surgery were unrelated to changes of end diastolic
volume with exercise; patients with both improved and worsening
ejection fraction on follow up showed 9% decrease in the mean end
diastolic volume after exercise. Results for end systolic volume were
different; patients with improved ejection fraction had a 19% decrease
in end systolic volume compared with a 4% increase in the group with a
worsening ejection fraction (p < 0.01). The group with the improved
ejection fraction had a positive contractile reserve of 6 (2)% with
exercise at baseline, while the group with the worsening ejection
fraction after surgery had a negative contractile reserve of 7 (2)%
with exercise at baseline (p < 0.001).

As in the patients with aortic regurgitation treated medically, the
preserved contractile reserve on exercise was significantly correlated
(r = 0.71, p < 0.001) with the change in left ventricular ejection
fraction following aortic valve surgery (fig 1B). All of the 13
patients with a positive contractile reserve at baseline had a
preserved ejection fraction at follow up. On the other hand, out of
the 13 patients with a negative contractile reserve at baseline, 10
showed a significant decrease in ejection fraction on follow up (2 =
15.2, p = 0.001) (table 6).

View this table:
[in this window]
[in a new window]
Table 6 Relation between change in ejection fraction on follow up
after aortic valve replacement and contractile reserve at baseline

Figure 2B compares the accuracy of change in end systolic volume with
exercise and the contractile reserve for predicting the change in
ejection fraction on follow up in patients with aortic regurgitation
undergoing aortic valve replacement. Contractile reserve was
significantly more sensitive (100%) as compared with change in end
systolic volume (40%). Both had a similar high specificity of 81% and
94% (NS), respectively. Contractile reserve had a slightly better
accuracy (88% v 73%) for predicting improvement in left ventricular
function than change in end systolic volume alone with exercise (NS).
Figure 4B gives ROC curves showing the sensitivity and specificity of
contractile reserve for predicting change in left ventricular ejection
fraction on follow up in patients undergoing aortic valve replacement.
A negative contractile reserve of 2% or less had a sensitivity and
specificity of 80% for predicting improvement in left ventricular
ejection fraction at follow up.

In a stepwise multiple regression model involving resting and exercise
indices of left ventricular function in all patients, contractile
reserve was the only significant variable to predict the change in
left ventricular ejection fraction on follow up ( ejection fraction =
0.81*CR + 3.48; p < 0.001).

Discussion
Top
Abstract
Introduction
Methods
Results
Discussion
References
Our findings in this study indicate that in asymptomatic patients with
aortic regurgitation and well preserved left ventricular function at
rest, contractile reserve identified by exercise echocardiography can
be useful in predicting the progressive deterioration of left
ventricular function. This appears to be valid both in patients
undergoing aortic valve replacement and in those with aortic
regurgitation and normal resting left ventricular function on medical
treatment. Specifically, failure to reduce end systolic volume or
increase the ejection fraction after exercise were specific but of
intermediate sensitivity for predicting left ventricular dysfunction
at follow up, contractile reserve being marginally more accurate
because of the contribution of smaller changes of diastolic volume
with exercise. The conventional indices of left ventricular dimensions
in diastole or systole, fractional shortening, and exercise
indicesincluding duration of exercise, rate-pressure product, and
workloadwere not helpful in predicting follow up left ventricular
function in either surgical patients or those treated medically. The
lack of influence of resting variables probably reflects the fact that
most individuals warranting surgery on these criteria proceeded to
surgery without recruitment into the study.

DETECTION OF LEFT VENTRICULAR DYSFUNCTION IN AORTIC REGURGITATION
In patients with aortic regurgitation, irreversible impairment of
myocardial contractility can be present in the absence of significant
symptoms,26 and can adversely affect prognosis even after aortic valve
replacement.4 14 Previous work has shown that fractional shortening
25% and end systolic diameter 55 mm may be used to guide the timing of
surgery for aortic regurgitation.5 27 However, these measurements are
relatively insensitive, especially compared with exercise ejection
fraction and end systolic volume,26 28 and some surgical series have
found them too restrictive, based on the postoperative course of
symptomatic and asymptomatic patients.14 15

Although diastolic and systolic left ventricular dimensions are well
correlated with the assessment of left ventricular volumes and
function in ventricles of normal size, with increasing left
ventricular diameter the relation becomes curvilinear, with pronounced
widening of the 95% confidence intervals for the estimated volume.29
The presence of aortic regurgitation also leads to alterations in left
ventricular geometrythe ventricle becomes more conical and wider at
the base,30 which may lead to an overestimation of the left
ventricular volume and ejection fraction if these are based on
diameter alone. In our patients, baseline left ventricular dimensions
were in the high normal range with a normal fractional shortening, yet
patients showed varying functional responses to exercise and a
decrease in ejection fraction on follow up. These results confirm the
presence of myocardial dysfunction before the left ventricular
systolic diameter exceeds 55 mm; in these patients direct measurement
of change in left ventricular volumes and ejection fraction with
dynamic exercise may add useful information.

LEFT VENTRICULAR RESPONSES TO STRESS IN AORTIC REGURGITATION
The results of this study suggest that a negative contractile reserve
is correlated with a decrease in ejection fraction on follow up in
both medical and surgical patients (fig 1). These data are concordant
with previous reports (not specifically in aortic regurgitation) that
inability to increase the ejection fraction and reduce the end
systolic volume with stress can be regarded as reliable early markers
for progressive deterioration of myocardial contractility.31 32

Previous data with aortic regurgitation are more confusing, however.
In a study comparing the exercise response in patients with aortic
regurgitation with controls,33 both groups showed a decrease in the
end systolic volume index and an increase in ejection fraction with
exercise. However, patients with symptomatic aortic regurgitation had
a significant increase in end systolic volume and a decrease in
ejection fraction with exercise, suggesting impaired myocardial
contractility. In contrast, Goldman and colleagues found no
correlation between the ejection fraction response to exercise and the
resting left ventricular dimensions or ejection fraction in a group of
patients with aortic regurgitation.34 The subgroup with an abnormal
ejection fraction response to exercise was characterised by an
increase in peak systolic wall stress. Our data may provide an
explanation for these findings, in that while a negative contractile
reserve is correlated with a decrease in ejection fraction on follow
up, the outcome of patients with a positive contractile reserve is
variable. Thus, although a positive contractile reserve confers a
better prognosis, other contributing factors may influence outcome.

In asymptomatic patients with aortic regurgitation, Branzi and
colleagues reported evidence of impaired myocardial contractility in
the form of reduced systolic elastance and increased systolic wall
stress in response to increased afterload.35 Again, only a small
proportion of the patients had reduced fractional shortening or
increased end systolic dimension at rest. In their series, angiotensin
was used to increase afterload, but this also has a mild negative
inotropic response. In contrast, exercise stress provides an index of
effort tolerance in parallel with an augmentation of heart rate, blood
pressure, and afterload similar to that invoked by normal daily
activity.

Examination of the left ventricular responses to stress in aortic
regurgitation has been applied clinically by Borer and colleagues,19,
using radionuclide techniques. In minimally symptomatic patients with
normal left ventricular function, these investigators found that the
change in ejection fraction with exercise (normalised for the change
in end systolic wall stress) was the strongest independent predictor
of outcome. Indeed, even when this complex variable was not included
in their model, change in ejection fraction with exercise could
provide most of the independent prognostic information. These results
are confirmed by our finding that the contractile reserve with
exercise is a useful and reliable predictor of progressive left
ventricular dysfunction on medical treatment and an even more
significant predictor of improvement of left ventricular function
after aortic valve replacement. The ability to gather these data with
exercise echocardiography, which is more widely available than
exercise nuclear ventriculography, represents an enhancement of the
feasibility of this approach.

MEDICAL VERSUS SURGICAL PATIENTS
The results of this study indicate that loss of contractile reserve is
quite specific as a harbinger of resting dysfunction, whether the
patient undergoes valve surgery or not. The outcomes of patients with
preserved contractile reserve are more variable, and are clearly
influenced by other factorsfor example, progression of the valvar
lesion, coexistent myocardial disease, and ischaemia. Given the
treatment of the valvar lesion and concomitant coronary surgery if
necessary in the surgical group, these confounding factors are more
prevalent in the medically treated group, and probably explain the
greater variation in the relation between contractile reserve and
evolution of left ventricular function.

LIMITATIONS
The results of the study need to be placed in the context of various
considerations relating to the study design. First, the Cleveland
Clinic Foundation is a referral institution for valve surgery and many
patients were available for study because of referrals regarding the
timing of surgery. This selection process may lead to
overrepresentation of patients with difficult management problems such
as severe regurgitation without gross left ventricular enlargement,
but given the impact of contractile reserve in both medically and
surgically treated groups, it is difficult to explain our findings on
the basis of patient selection. Second, the duration of follow up was
relatively short and further alterations in left ventricular function
(and especially clinical condition) might have been seen if the group
had been followed for longer. Third, while the patients of interest
(asymptomatic, relatively small left ventricular cavity) are a
subgroup of a large number of patients with aortic regurgitation, in
absolute terms the numbers of patients are relatively small. Finally,
the disadvantage of observational studies is that they present
relations but neither prove causation nor explain the findings.

We believe that the impact of contractile reserve on outcome reflects
the fact that the exercise response of the ventricle is more
representative of left ventricular compromise than is resting
function, but we cannot exclude the possibility that another mechanism
is at work. Similarly, the finding that the increment of ejection
fraction on follow up was greatest in patients with more enlarged
ventricles preoperatively (table 3) most probably reflects the fact
that the short follow up precludes the resolution of left ventricular
enlargement. The volume changes following recovery of the myocardium
in this situation may therefore have exceeded those in smaller
ventricles. It is important to recognise that these patients did not
have abnormal resting volumes at baseline, so this relation concerns
volumes that are at the upper limit of normal. Alternative
explanations may include changes in left ventricular geometry in
patients with aortic regurgitation; loss of long axis function as the
ventricle becomes more spherical may engender a reduction of ejection
fraction despite preserved fractional shortening in a small but not in
a larger ventricle.

CLINICAL IMPLICATIONS
Left ventricular function is a major determinant of long term
prognosis,3 and the principal aim in the management of patients with
chronic asymptomatic aortic regurgitation is to be able to predict and
pre-empt the development of irreversible left ventricular systolic
dysfunction. In this study of asymptomatic patients with normal
resting left ventricular function, conventional indices of left
ventricular size and function, exercise capacity, and clinical
characteristics did not predict the latent left ventricular
dysfunction on medical follow up or the improvement in left
ventricular function after aortic valve replacement surgery.
Contractile reserve and the decrease in end systolic volume with
exercise measured by exercise echocardiography were predictive of
progressive deterioration of left ventricular function in these
patients.

Decision making with respect to the timing of surgery in aortic
regurgitation may be difficult. Excessive delay risks irreversible
left ventricular enlargement owing to the chronic volume load.
However, unlike mitral regurgitation, valve repair is generally not
feasible, so early surgery exposes the patient prematurely to the
risks inherent in having a prosthetic valve. The decision to proceed
with surgery in an asymptomatic patient is multifactorial, but the
assessment of contractile reserve may be a useful adjunct to resting
left ventricular size and function. This approach has the benefit of
involving widely available exercise and echocardiographic equipment
rather than requiring referral to a nuclear cardiology facility. While
there is undoubtedly a learning curve in the performance of exercise
echocardiography, image interpretation is less challenging to the
observer than evaluation of regional wall motion abnormalities. New
techniques such as tissue Doppler may be useful in quantifying the
left ventricular response to stress and obviate the process of tracing
systolic and diastolic contours to obtain the ejection fraction.

References
Top
Abstract
Introduction
Methods
Results
Discussion
References

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--------------------------------------------------------------------------------
© 2000 by Heart

This article has been cited by other articles:

M. Rothenburger, K. Drebber, T. D.T. Tjan, C. Schmidt, C. Schmid, T.
Wichter, H. H. Scheld, and M. Deiwick
Aortic valve replacement for aortic regurgitation and stenosis, in
patients with severe left ventricular dysfunction
Eur. J. Cardiothorac. Surg., May 1, 2003; 23(5): 703 - 709.
[Abstract] [Full Text] [PDF]

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