Impact of mechanical versus bioprosthetic heart valve on severe maternal morbidity during delivery hospitalizations

Historical studies suggested that patients with mechanical (versus bioprosthetic) heart valves were at higher risk for adverse pregnancy outcomes. Whether this difference persists with contemporary valve designs is unknown. We used a large administrative dataset to compare pregnancy outcomes of women with mechanical versus bioprosthetic heart valves. This was a retrospective cohort study using the 2013-2018 National Readmissions Database, which comprises ∼60% of US hospitalizations. Diagnosis and procedure codes were used to identify delivery hospitalizations, comorbidities, and outcomes. The primary exposure was presence of a prosthetic heart valve (mechanical, bioprosthetic, or both). The primary outcome was severe maternal morbidity (SMM) during the delivery stay. Adjusted relative risk regression, incorporating weighting data for nationally representative estimates, was used to evaluate the association between valve type and outcomes, adjusted for patient and facility characteristics. There were a national estimate of 11,556,136 delivery hospitalizations included in the sample, of which 1,296 had a mechanical valve, 690 a bioprosthetic valve, and 19 both. Demographic and clinical characteristics were similar regardless of valve type (Table 1). In unadjusted analyses, patients with mechanical valves had higher rates of SMM, non-transfusion SMM, cardiac-related SMM, and preterm birth when compared with bioprosthetic valves (Figure 1A). In adjusted analyses, rates of SMM, but not other outcomes, were higher for mechanical valves when compared with bioprosthetic (adjusted OR: 1.77; 95% CI 1.01, 3.11; Figure 1B). Rates of SMM, non-transfusion SMM, and preterm birth were higher for patients with any prosthetic valve compared to no prosthetic valve. Mechanical valves were associated with a higher rate of SMM when compared with bioprosthetic valves. This information may be helpful in counseling patients prior to valve replacement or during pregnancy care after valve replacement.View Large Image Figure ViewerDownload Hi-res image Download (PPT)