Angiotensin-converting enzyme inhibition improves cardiac fatty acid metabolism in patients with congestive heart failure

This study aimed to examine whether angiotensin-converting enzyme (ACE) inhibition improved cardiac fatty acid metabolism in patients with congestive heart failure (CHF). Myocardial I-123-beta-methyliodophenylpentaclecanoic acid (I-123-BMIPP) imaging was performed in 25 patients with CHF and in 10 control subjects. Myocardial I-123-BMIPP images were obtained 30 min and 4 h after tracer injection. The heart-to-mediastinum (H/M) ratio of I-123-BMIPP uptake and the washout rate of I-123-BMIPP from the myocardium were calculated. Patients were given enalapril for 6 months, and I-123-BMIPP imaging was repeated. H/M ratios on early and delayed images were lower in CHF patients than in normal controls (P<0.01). The washout rate of I-123-BMIPP from the myocardium was faster in CHF patients than in controls (P < 0.01). As the severity of the New York Heart Association (NYHA) functional class increased, the H/M ratio decreased and the washout rate increased. The washout rate of I-123-BMIPP was inversely correlated with left ventricular fractional shortening (R = - 0.62, P < 0.01). ACE inhibition with enalapril increased the H/M ratio on delayed images (P<0.05) and reduced the washout rate of I-123-BMIPP (P<0.05) in CHT patients. These data suggest that: (1) angiotensin II-mediated intracellular signalling activation may be a possible mechanism for the decreased myocardial uptake and enhanced washout of I-123-BMIPP in heart failure patients; and (2) the improvement in fatty acid metabolism by ACE inhibition may represent a new mechanism for the beneficial effect of this therapy in heart failure. ((C) 2003 Lippincott Williams & Wilkins).