NEW YORK (Reuters Health) – While some patients with acute coronary syndrome (ACS) and elevate natriuretic peptide levels can benefit from treatment with various suppressors of the renin-angiotensin-aldosterone system (RAAS), the benefit does not appear to include those with preserved left ventricular function.

That finding is reported in the European Heart Journal, published online June 17, by investigators with the AVANT GARDE-TIMI 43 trial.

“This was a short-term “proof-of-concept” study, where the change in natriuretic peptides was the primary endpoint. Therefore, we cannot know if extended therapy with RAAS inhibition in this patient population would reduce cardiovascular events,” lead author Dr. Benjamin Scirica told Reuters Health by email.

Dr. Scirica, at Brigham and Women’s Hospital and Harvard Medical School in Boston, Massachusetts, and colleagues in the TIMI Study Group enrolled 1100 stabilzed ACS patients in the trial if they had elevated levels of natriuretic peptides but no evidence of heart failure and their ejection fraction was at least 40%. They were randomized to treatment with the direct renin inhibitor aliskiren, valsartan, their combination, or placebo.

By week 8, there were no differences in the drop in natriuretic peptides in any of the treatment arms. ProB-type natriuretic peptide, as a representative example, declined by 42% with placebo, 44% with aliskiren, 39% with valsartan, and 36% in combination arm.

“We demonstrated that the RAAS inhibition exerted the expected physiologic effects, including a small reduction in BP, compared to placebo,” Dr. Scirica noted.

“The decline in natriuretic peptides in the placebo group was greater than expected,” he continued, “which suggests that the elevation in natriuretic peptides among patients with preserved LV function may not be the result of hemodynamic stress as much as the initial ischemic insult of ACS, and therefore agents such as RAAS inhibitors, which in the short-term modulate hemodynamics, may not have a significant therapeutic action.”

Nonetheless, Dr. Scirica concluded, “The situation may well be different in patients with evidence of heart failure or reduced LV function, where RAAS inhibitors have shown superiority versus placebo.”

Reference:

http://dx.doi.org/10.1093/eurheartj/ehq190

Eur Heart J 2010.