Recovery of load-induced left ventricular diastolic dysfunction by coenzyme Q10: echocardiographic study.

UNLABELLED: Load-induced cardiac dysfunction (LCD), in which a supernormal left ventricular (LV) systolic performance at rest decreases due to an afterload challenge, usually occurs among children with mitral valve prolapse (MVP). However, diastolic performance is also important because relaxation, like contraction, is based on a process that requires energy. The aim of this study was to examine LV diastolic response patterns to stress in patients with LCD before and after coenzyme Q10 (CoQ) therapy and in controls. The D-E slope, E-F slope and maximal diastolic endocardial velocity were used as echographic diastolic indices. Thirty subjects, aged 9-16 years, were divided into four groups: group 1, 10 normals; group 2, 10 patients with LCD; group 3, the same 10 as in group 2, who recovered with CoQ, 3.0-3.4 mg/kg/day for 7 days; group 4, 10 asymptomatic children with MVP. The heart rate, both at rest and during handgrip (HG), showed little intergroup difference. Only in group 2, were the ejection fraction and all the diastolic indices greater than in the other groups, but these became subnormal with HG. In the other groups, these indices increased with HG to a similar extent, although resting values were smaller than in group 2.

IN CONCLUSION: (1) in normal hearts and in hearts with LCD, diastolic performance mimicked systolic performance both in resting and loading conditions; (2) CoQ improved not only the load-induced systolic but also the diastolic dysfunctions in a similar time-course, and (3) mechanical stiffness of the cardiac tissue may not be a cause of load-induced diastolic dysfunction, because the dysfunction was quickly resolved with CoQ therapy. CoQ may be a key substance which affects a common bioenergetic process in contraction and relaxation, to keep these functions normal.