What is the etiology of peripartum cardiomyopathy? The etiology is unknown; multiple etiologies have been proposed. The most substantiated etiology is viral myocarditis.. It is thought that the relative immunosuppression of pregnancy may increase the risk of viral myocarditis (JEM, V. 36, pg. 141). Differential includes hypertensive pulmonary, mobilization of volume following delivery, pulmonary embolism, and pneumonia. the workup involves an echocardiogram to demonstrate decrease systolic function and exclusion of other causes. The mainstay of treatment is afterload reduction (nitroprusside) and diuretics.