Background: Pregnant women with cardiomyopathy (CM) have higher rates of major adverse cardiovascular events (MACE) and fetal adverse clinical events (FACE) than those with other heart disease (HD) (congenital, valvular, or arrhythmia) and no HD, per a prior cohort. 1 Fetuses of mothers with CM are at higher risk for death, premature delivery, underweight, respiratory distress, and lower APGAR scores compared to those with HD. We sought to identify whether pregnant women with known CM or HD demonstrate a pattern of placental changes. Hypothesis: We anticipate pregnant women with a history of CM will have higher rates of abnormal placental characteristics compared with those with HD. Methods and results: We studied 86 pregnancies in women with CM or HD. Of these, 52 (60%) had HD and 34 (40%) had CM. Pathologic analyses were performed on 53 HD and 37 CM placentas. Gestational age in the HD and CM groups were different (38.6 vs 35.5, p < 0.001), as was the incidence of gestational hypertension (21 vs 50%, p 0.003). Among the maternal HD group, 44% had history of congenital heart disease, 33% prior corrective cardiac surgery and 31% had history of arrhythmia. Placental and fetal weight were lower among CM patients compared to those with HD (396 vs. 478 grams, p 0.007; and 2443 versus 3181 grams, p<0.001, respectively). Placentas of those patients with CM compared to those with HD were also more likely to have ischemic changes (65% vs. 34%, p 0.005) and be immature (60% vs. 9%, p<0.001). Pathological villous vascular congestion, fetal membrane abnormalities, fetal surface coloration abnormalities, umbilical cord abnormalities and extent of subchorionic fibrin and placenta calcification were not significantly different between the two groups. Conclusion: Abnormal placental pathologic characteristics such as low weight, ischemic changes and immaturity may contribute to fetal adverse events in pregnant women with CM. 1 Koutrolou-Sotiropoulou P, Parikh PB, Miller C, Lima FV, Butler J, Stergiopoulos K. Impact of Heart Disease on Maternal and Fetal Outcomes in Pregnant Women. Am J Cardiol In Press 2015.