Not true, see

Mehra MR, Lavie CJ, Ventura HO, Milani RV.
Fish oils produce anti-inflammatory effects and improve body weight in
severe heart failure.
J Heart Lung Transplant. 2006 Jul;25(7):834-8. Epub 2006 May 24.
PMID: 16818127 [PubMed - indexed for MEDLINE]
<http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=Abstra
ctPlus&list_uids=16818127>

   "... CONCLUSIONS: Fish oils decrease TNF-alpha production in heart
   failure and improve body weight. Fish oil therapy may represent a
   novel therapeutic approach in late-stage heart failure
   characterized by cardiac cachexia."

Lennie TA, Chung ML, Habash DL, Moser DK.
Dietary fat intake and proinflammatory cytokine levels in patients
with heart failure.
J Card Fail. 2005 Oct;11(8):613-8.
PMID: 16230265 [PubMed - indexed for MEDLINE]
<http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=Abstra
ctPlus&list_uids=16230265>

   "... TNF-alpha levels were elevated in patients with diets
   higher versus lower in saturated (6.9 +/- 5 versus 4.2 +/- 2
   pg/mL) and trans fats (6.8 +/- 4.5 versus 4.5 +/- 2.8 pg/mL).
   Patients consuming diets higher in polyunsaturated fats had
   lower sTNF-R1 (2391 +/- 1010 versus 3373 +/- 2098 pg/mL) and
   sTNF-R2 (3803 +/- 1187 versus 5974 +/- 3275 pg/mL) levels.
   Higher omega-3 intake produced similar results: sTNF-R1 (2323
   +/- 1304 versus 3307 +/- 1973) and sTNF-R2 (4117 +/- 2646
   versus 5409 +/- 2801). Event-free survival was decreased in
   patients with higher TNF-alpha and sTNF-R1 levels. ..."

Witte KK, Clark AL.
Fish oils--adjuvant therapy in chronic heart failure?
Eur J Cardiovasc Prev Rehabil. 2004 Aug;11(4):267-74. Review.
PMID: 15292759 [PubMed - indexed for MEDLINE]
<http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=Abstra
ctPlus&list_uids=15292759<

   "Despite advances in medical management and device therapy,
   chronic heart failure (CHF) remains a condition of high
   mortality and poor quality of life. Patients with CHF endure
   frequent admissions to hospital, with exacerbations of
   breathlessness or recurrent acute myocardial infarction and
   have a high incidence of sudden death. A high intake of marine
   polyunsaturated fatty acids (PUFAs) is associated with lower
   cardiovascular mortality in the general population, and
   diabetics, and can reduce cardiovascular deaths post-
   infarction. Many of the effects of PUFAs could be of benefit in
   CHF patients. They can improve endothelial function, reduce
   vascular tone, reduce platelet aggregability, improve
   myocardial relaxation, stabilize myocardial cells by prolonging
   the refractory period, and lead to increased appetite and
   weight gain. They also have potentially important immune-
   modulating effects, reducing cytokine production and release
   and altering prostaglandin metabolism. In this review article
   we discuss the potential benefits of PUFA supplementation in
   CHF patients using data from clinical trials and in vitro
   experiments."