Antifailure therapy including spironolactone improves left ventricular energy supply-demand relations in nonischemic dilated cardiomyopathy

Abstract

Background-Left ventricular (LV) energy supply-demand imbalance is postulated to cause "energy starvation" and contribute to heart failure (HF) in nonischemic dilated cardiomyopathy (NIDCM). Using cardiac magnetic resonance (CMR) and [11C] acetate positron emission tomography (PET), we evaluated LV perfusion and oxidative metabolism in NIDCM and the effects of spironolactone on LV supply-demand relations. Methods and Results-Twelve patients with NIDCM underwent CMR and PET at baseline and after ≥6 months of spironolactone therapy added to a standard HF regimen. The myocardial perfusion reserve index (MPRI) was calculated after gadolinium injection during adenosine, as compared to rest. The monoexponential clearance rate of [ 11 C] acetate (k mono) was used to calculate the work metabolic index (WMI), an index of LV mechanical efficiency, and k mono /RPP (rate-pressure product), an index of energy supply/demand. At baseline, the subendocardium was hypoperfused versus the subepicardium (median MPRI, 1.63 vs. 1.80; P<0.001), but improved to 1.80 (P<0.001) after spironolactone. The WMI increased (P=0.001), as did k mono /RPP (P=0.003). These improvements were associated with reverse remodeling, increased LV ejection fraction, and decreases in LV mass and systolic wall stress (all P<0.002). Conclusions-NIDCM is associated with subendocardial hypoperfusion and impaired myocardial oxidative metabolism, consistent with energy starvation. Antifailure therapy improves parameters of energy starvation and is associated with augmented LV performance.