Apoptosis in heart failure: A tale of heightened expectations, unfulfilled promises and broken hearts

Although apoptosis contributes significantly to remodeling of the fetal heart during evolution of cardiac chambers and correct routing of the great vessels, it has been believed that apoptosis does not occur in terminally differentiated adult cardiac muscle cells. However, apoptosis has recently been demonstrated in animal models of heart failure as well as in explanted hearts from patients with end-stage heart failure undergoing cardiac transplantation. Ventricular dilatation and neurohormonal activation, the hall-marks of heart failure, lead to upregulation of transctription factors, induce muscle cell hypertrophy and prepare cells for entry into the cell-division cycle. However, since terminally differentiated myocytes cannot divide, they die by apoptosis. It has been proposed that low-grade apoptosis in failing heart may be responsible for inexorable decline in left ventricular function. Better understanding of the molecular and cellular basis of apoptosis in the failing myocardium may lead to development of strategies aimed at preventing progressive myocyte loss and deterioration in left ventricular function.