Inhibition of Cardiac Myocyte Apoptosis Improves Cardiac Function and Abolishes Mortality in the Peripartum Cardiomyopathy of Gαq Transgenic Mice

Background-Although the occurrence of cardiac myocyte apoptosis during heart failure has been documented, its importance in pathogenesis is unknown. Transgenic mice with cardiac-restricted overexpression of Gαq exhibit a lethal, peripartum cardiomyopathy accompanied by apoptosis. To test whether apoptosis is causally linked to heart failure, we assessed whether inhibiting this cell death would improve left ventricular function and survival in the Gαq peripartum cardiomyopathy model. Methods and Results-The potent polycaspase inhibitor IDN-1965 or vehicle was administered subcutaneously to Gαq mice by osmotic minipump beginning on day 12 of pregnancy and continuing through euthanasia at day 14 postpartum. As expected, IDN-1965 markedly suppressed cardiac caspase-3-like activity (86.5%; P<0.01), accompanied by reduction in the frequency of cardiac myocyte apoptosis from 1.9±0.3% to 0.2±0.1% (P<0.01). Animals receiving IDN-1965 exhibited significant improvements in left ventricular end-diastolic dimension (vehicle, 4.7±0.1 mm; IDN-1965, 4.2±0.1 mm; P<0.01), fractional shortening (vehicle, 30.7±1.2%; IDN-1965, 38.9±1.0%; P<0.01), positive (vehicle, 3972±412; IDN-1965, 5870±295; P<0.01) and negative (vehicle, 2365±213; IDN-1965, 3413±201; P<0.01) dP/dt, and complete suppression of mortality (vehicle, 6 of 20 died; IDN-1965, 0 of 14 died; P<0.05). Conclusions-Reduction in cardiac myocyte apoptosis by caspase inhibition improved left ventricular function and survival in pregnant Gαq mice. These data indicate that cardiac myocyte apoptosis plays a causal role in the pathogenesis of cardiomyopathy in this model. Caspase inhibition may provide a novel therapeutic target for heart failure.