Interrelation between myocardial oxidative metabolism and diastolic function in patients undergoing surgical ventricular reconstruction

Abstract

Diastolic function is impaired in patients with end-stage heart failure. Favorable structural changes by surgical ventricular reconstruction (SVR) are thought to improve diastolic function, however, previous studies reported the contradictory results. We hypothesized that cardiac oxidative metabolism and diastolic dysfunction might improve in parallel to the reduction of left ventricular chamber size after SVR. We studied 11 patients underwent SVR associated with mitral valve repair for end-stage heart failure due to dilated cardiomyopathy. Diastolic function was assessed by echocardiography and myocardial oxidative metabolism was measured by the monoexponential clearance (k-mono) of (11)C-acetate positron emission tomography at baseline and 1month after SVR. All patients had preoperative severe diastolic dysfunction [E/A 4.11 ± 1.18, deceleration time (DT) 134 ± 26ms]. The study patients were divided into 2 groups according to the changes in diastolic function after SVR; unchanged or worsened diastolic function in 6 patients (55%, Non-responder) and improved diastolic function in 5 (45%, Responder). K-mono and wall stress decreased only in responder. The changes in k-mono before and after SVR correlated with those in deceleration time (r = -0.63; p < 0.05) and wall stress (r = 0.75; p < 0.01). Improvement of diastolic dysfunction in patients with end-stage heart failure by SVR was in parallel to that in oxidative metabolism. It suggests that SVR reduced excessive metabolism during the diastolic phase, in part, via the improvement in diastolic function and the reduction in LV wall stress.