Hypertensive disorders of pregnancy and peripartum cardiomyopathy: A nationwide cohort study

Abstract

Background Peripartum cardiomyopathy (PPCM) is a serious cardiac disorder occurring late in pregnancy or early in the postpartum period. We examined associations between hypertensive disorders of pregnancy (HDP: preeclampsia and gestational hypertension) and PPCM, accounting for other pregnancy-related risk factors for PPCM. Methods Using nationwide Danish register data, we constructed a cohort of all women with ≥1 live birth or stillbirth in Denmark between 1978 and 2012. Using log-linear binomial regression and generalized estimating equations, we estimated risk ratios (RRs) for PPCM associated with HDP of varying severity. Results In a cohort of 1,088,063 women with 2,078,822 eligible pregnancies, 126 women developed PPCM (39 in connection with an HDP-complicated pregnancy). The risks of PPCM were significantly higher in women with HDP-complicated pregnancies than in women with normotensive pregnancies (severe preeclampsia, RR 21.2, 95% confidence interval [CI] 12.0–37.4; moderate preeclampsia, RR 10.2, 95% CI 6.18–16.9; gestational hypertension, RR 5.16, 95% CI 2.11–12.6). The RRs for moderate preeclampsia and gestational hypertension were not significantly different from one another (p = 0.18); the RR for severe preeclampsia was significantly different from the RR for moderate preeclampsia and gestational hypertension combined (p = 0.02). Conclusions Although 70% of PPCM occurred in women with normotensive pregnancies, HDPs were associated with substantial increases in PPCM risk that depended on HDP severity. The heart’s capacity to adapt to a normal pregnancy may be exceeded in some women already susceptible to cardiac insult, contributing to PPCM. HDPs, severe preeclampsia in particular, probably represent an additional cardiac stressor during pregnancy.

Pre-pregnancy Obesity and the Risk of Peripartum Cardiomyopathy

“…However, some other studies have reported prevalences similar to our study. 16,25,28 When we ran the sensitivity analysis including women with diagnoses for nonperipartum cardiomyopathy or other heart disease, the prevalence was 3.8 per 10,000 births-which is more in alignment with previous studies. Associations between obesity and peripartum cardiomyopathy remained but were somewhat attenuated when using this broader case definition.…”

“…2,8,16,[25][26][27] In particular, some have used diagnostic billing codes to identify obesity, which is known to have poor sensitivity 2,[25][26][27] or lacked access to postpartum records, although a large proportion of cases occur after childbirth hospitalization. 2,25 Some studies have also included women with other known heart conditions, which may misclassify women with peripartum cardiomyopathy, 25 had small sample sizes 16 or were restricted to maternal deaths related to peripartum cardiomyopathy although the vast majority of women survive. 8 The objective of this study was to determine the association of pre-pregnancy BMI with peripartum cardiomyopathy, using data from more than 2.5 million women who gave birth in California from 2007 to 2012.…”

The Association between Hypertensive Disorders of Pregnancy and Peripartum Cardiomyopathy

“…To explore the association between HDP and PPCM, a cohort study was done in Denmark by Behrens et al It identified 126 women with PPCM, 39 of whom developed HDP whereas 87 were normotensive [13]. Most cases (82% vs. 81.6%) were diagnosed either during the final month of pregnancy or the first month of postpartum, both in women with or without HDP.…”

“…Several studies have been carried out at different subpopulations in many countries that sheds light on the various common and different characteristics observed for the two phenomena. The reported incidence of HDP among PPCM patients ranges from 2-68%.In the most recent study by Behrens et al, a cohort of >2 million pregnant females across Denmark revealed that the risk of PPCM in women with HDP was 5-21 times higher than in normotensive women, and the risk increased with increasing severity of hypertension [13] (Figure 1).…”

“…Despite the strong association between HDP and PPCM, most cases of PPCM (69%) occur in healthy normotensive pregnant females [13]. Certain susceptible women are unable to handle the hemodynamic stresses of pregnancy.…”