Peripartum heart failure: idiopathic cardiomyopathy or compounding cardiovascular events?

During a 12-year period, when more than 106,000 women were delivered, 28 women with peripartum heart failure of obscure etiology that initially was diagnosed as peripartum cardiomyopathy were studied. None had obvious underlying cardiac disease or iatrogenic fluid overload, and in all an assiduous search for underlying cardiovascular disease was launched. In 21 of these 28 women, heart failure was attributed to chronic underlying disease (chronic hypertension in 14, forme fruste mitral stenosis in four, and morbid obesity in one) or viral myocarditis. Importantly, these women also had multiple compounding cardiovascular factors--preeclampsia, cesarean section, anemia, and infection--which, when superimposed on those of pregnancy, acted in concert to cause heart failure. In seven women, the cause for cardiomegaly and global hypokinesis was not found, and peripartum cardiomyopathy was diagnosed. Compared with women with explicable causes of peripartum heart failure, these women did poorly: six had persistent cardiomegaly and heart failure, and four of these died within four months to eight years. From these observations, the authors conclude that idiopathic peripartum cardiomyopathy is uncommon, and that in most women with peripartum heart failure of obscure etiology, underlying chronic disease will be identified. Heart failure in these women ensues when the cardiovascular demands of normal pregnancy are amplified further by common pregnancy complications superimposed upon these underlying conditions that cause compensated ventricular hypertrophy.