High output failure in patients with peripartum cardiomyopathy: a comparative study with dilated cardiomyopathy. Although few studies have reported on relatively preserved ventricular function in patient with peripartum cardiomyopathy, the condition is usually believed to have the typical low-output congestive hemodynamic pattern of the dilated congestive cardiomyopathies. Two groups of patients, 14 with peripartum cardiomyopathy and 12 with dilated congestive cardiomyopathy who were matched for gender and age, were studied. They had normal blood pressure and similar New York Heart Association functional class, nutritional status, thyroid function and routine laboratory evaluation. All patients were catheterized during stable in-hospital compensation of heart failure, which was achieved by bed rest, sodium restriction, and administration of digoxin and diuretics long (more than 3 months) after delivery. Significant differences (p less than 0.05) between patients with peripartum cardiomyopathy and those with dilated congestive cardiomyopathy were observed in regard to: (1) cardiac index: 3.34 +/- 1.36 L/min/m2 versus 2.24 +/- 0.72 L/min/m2, (2) systemic vascular resistance: 1713 +/- 567 dynes.sec.cm-5 versus 2194 +/- 603 dynes.sec.cm-5, (3) right ventricular stroke work index: 8.6 +/- 4.2 g.M/m2 versus 14.8 +/- 8.2 g.M/m2 in the peripartum cardiomyopathy and the dilated congestive cardiomyopathy groups, respectively. Three of the patients with peripartum cardiomyopathy had resting cardiac index values that were even higher than the normal upper limit for our laboratory (4.5 L/min/m2): 4.80, 5.70, and 5.63 L/min/m2. They also had nearly normal left ventricular ejection fractions: 0.68, 0.41, and 0.51, respectively. These results indicate that, unlike the common dilated cardiomyopathy, the hemodynamic pattern in patients with peripartum cardiomyopathy is not homogeneous, and some patients have high-output failure and near normal left ventricular function. 