Disease-specific remodeling of cardiac mitochondria after a left ventricular assist device

Background. Failing hearts can exhibit elements of structural and molecular "reverse remodeling" after support with a left ventricular assist device (LVAD). The present study examined LVAD-induced remodeling of cardiac mitochondria. Methods. Left ventricular tissue from 20 failing and 21 LVAD-supported hearts, catagorized as ischemic (ICM) or dilated (DCM) cardiomyopathy and four nonfailing hearts were studied. Myocyte mitochondrial ultrastructure was assessed by high-performance liquid chromatography determination of cardiolipin, a specific lipid component of the inner membrane, and its three major molecular species: L-4, L3O, and L2O2. Results. Both failing and LVAD-supported hearts exhibited a reduction in cardiolipin content that was independent of the type of cardiomyopathy. However, in failing/ICM hearts, there was a 25% increase in the L-4/L3O ratio and a 70% increase in the L-4/L2O2 ratio, indicating a change in cardiolipin composition. These alterations were normalized by LVAD support. In sharp contrast, molecular species ratios in DCM hearts were the same as those in nonfailing hearts regardless of whether LVAD support had been used or not. Conclusions. These data demonstrate LVAD-induced reverse remodeling of myocyte cardiolipin composition in ICM but not DCM hearts.