A retrospective study of mode of delivery in patients with hypertrophic vs other forms of cardiomyopathy

A better understanding of optimal modes of delivery is important for guiding peripartum recommendations for patients with cardiomyopathy and may differ by cardiomyopathy type.

This study examines the association between mode of delivery and maternal morbidity events in patients with different types of cardiomyopathy: hypertrophic, dilated, peripartum, and other or unspecified.

This retrospective cohort study used the Premier Healthcare inpatient database, including patients aged 12 to 55 years who gave delivered after 25 weeks' gestation with a diagnosis of cardiomyopathy between 2016 and 2020. Patients were categorized into hypertrophic, dilated, peripartum, or other or unspecified cardiomyopathy subtypes based on International Classification of Diseases, Tenth edition codes. Mode of delivery was classified as vaginal or cesarean. Cesarean delivery was further classified as planned or intrapartum cesarean delivery. The exposure was the intended mode of delivery to simulate real-life delivery planning decisions (vaginal delivery, both completed and intrapartum cesarean delivery, vs planned cesarean delivery). An analysis by actual mode of delivery was also performed (completed vaginal deliveries vs intrapartum cesarean delivery and planned cesarean delivery). Outcomes included severe maternal morbidity, blood transfusion, 90-day readmission, and inotrope use. Each outcome was analyzed by cardiomyopathy subtype. Statistical analyses included descriptive comparisons and multivariable logistic regression, adjusting for age, insurance type, and comorbidities.

There were 1872 deliveries across all cardiomyopathy subtypes. Among the subtypes, the peripartum cardiomyopathy group displayed the highest rates of intrapartum cesarean delivery (34%) and severe maternal morbidity (32%), and the hypertrophic cardiomyopathy group displayed the lowest rates (20% and 7%, respectively). There were no significant differences in severe maternal morbidity among patients with dilated (odds ratio, 1.50 [0.68-3.27]), peripartum (odds ratio, 1.32 [0.87-2.03]), or other (odds ratio, 0.80 [0.51-1.24]) cardiomyopathy when comparing intended cesarean vs intended vaginal delivery. In contrast, in the hypertrophic cardiomyopathy group, the odds ratio was 3.73 [1.56-13.57] for severe maternal morbidity when comparing intended cesarean vs intended vaginal delivery. In the analysis by actual mode of delivery, all cardiomyopathy subgroups had greater odds of severe maternal morbidity in cesarean vs vaginal delivery: hypertrophic (odds ratio, 3.98 [1.06-14.91]), dilated (odds ratio, 4.05 [1.64-10.00]), peripartum (odds ratio, 2.47 [1.50-4.07]), and other (odds ratio, 2.18 [1.36-3.51]). Among patients who delivered via cesarean delivery, the odds of severe maternal morbidity were higher across all subgroups, and rates of severe maternal morbidity events among the group requiring intrapartum conversion to cesarean delivery were high, suggesting this population to be at the highest risk.

Among patients with hypertrophic cardiomyopathy, a trial of labor was associated with lower morbidity compared with a planned cesarean delivery, implying either that more morbid patients were selected for cesarean or that cesarean delivery was uniquely less optimal than vaginal delivery for hypertrophic cardiomyopathy patients in comparison to other cardiomyopathies in this cohort. Although a trial of labor is the recommended mode of delivery for most patients with cardiomyopathy, patients at greatest risk are those who require intrapartum conversion to cesarean. Prospective studies are needed to determine the safe length of time in labor in these patients and the factors leading to unplanned cesarean delivery.