COPENHAGEN, DENMARK — Hypertensive disorders in pregnancy (HDP) are associated with an increased risk of cardiomyopathy years after an affected pregnancy and regardless of hypertension severity, a large registry study involving one million Danish women shows.
"The fact that we could drop the first 5 years after pregnancy and still see this risk was really fascinating," senior author Dr Heather Boyd (Statens Serum Institut, Copenhagen, Denmark) told heartwire from Medscape.
Women who develop preeclampsia or hypertension during pregnancy are known to be at greater risk for cardiomyopathy in the peripartum period, covering the last month of pregnancy until 5 months after delivery.
More recent reports of cardiac dysfunction and remodeling after preeclampsia, however, argue for a persistent risk of cardiomyopathy outside the peripartum window.
"There are other studies linking preeclampsia and the future risk of cardiovascular disease, particularly atherosclerotic disease. This adds one step further connecting it sort of independently of atherosclerotic disease with dilated cardiomyopathy," Dr Katharine French (Women's Cardiac Center, Brown University, Providence, RI), who was not involved in the study, said.
In the study, published in the March 8, 2016 issue of the Journal of the American Medical Association, 11% of all cardiomyopathy events occurred in women with a history of hypertensive disorder of pregnancy, defined as severe preeclampsia, moderate preeclampsia, or gestational hypertension.
Rates of cardiomyopathy in all three of these groups were significantly higher than in women with a normotensive pregnancy (adjusted hazard ratios [aHRs] 2.20, 1.89, 2.06).
Limiting the analysis to dilated cardiomyopathy produced similar results (aHRs 3.17, 2.56, 2.58), "suggesting that the associations may primarily be driven by dilated cardiomyopathy," the authors report.
The investigators used national patient and birth registries in Denmark to identify 1,075,763 women with 2,067,633 pregnancies ending in a live birth or stillbirth between 1978 and 2012. Of these, 76,108 were complicated by a hypertensive disorder. About 6% of the Danish women were immigrants, Boyd said.
The analysis excluded women with any cardiovascular disease or diabetes more than 1 month before their first delivery.
Boyd emphasized that even though they identified an increased risk of cardiomyopathy, the absolute risk was small. Rates in women with a history of an HDP was just 14.6 to 17.3 cases per 100,000 person-years.
"Although the American Heart Association recommends monitoring for ischemic heart disease following preeclampsia, a similar recommendation would not be justified for a rarer condition such as cardiomyopathy, regardless of the strength of the observed association with HDP," Boyd and her colleagues advise. "On the other hand, it seems prudent to suggest that physicians consider this association in the diagnostic workup of women with a history of HDP presenting with possible symptoms of heart failure."
If physicians ask just one simple question, "Do you have a history of hypertensive disorders of pregnancy?" and the answer is "Yes," it could push their thinking more toward the heart rather than the lungs, asthma, or obesity, Boyd said.
French wholeheartedly agreed that screening with echocardiogram is not justified based on the study and that physicians should be making the connection. Whether they're actually asking about pregnancy history in the 50-year-old with heart-failure symptoms is another matter.
"Absolutely not," she said. "I think this connection is a relatively new one, and it takes a long time to be adopted into practice. I think that with more of a focus now on women's cardiovascular health and distinguishing the differences between how men and women present, there is more of a focus turned toward that, but still in the general land of cardiology, I think it's still not present enough."
Dr Katherine Economy (Brigham and Women's Hospital, Boston, MA) told heartwire the size of the study is impressive but that the almost exclusively white cohort limits applicability of its results. African American women are known to be at greater risk for preeclampsia and peripartum cardiomyopathy and have worse outcomes when they get these conditions.
The strikingly similar risk of cardiomyopathy regardless of disease severity is another area ripe for further research, as obstetricians view risk quite differently for women with severe preeclampsia and those with mild gestational hypertension, Economy said.
Boyd said the strengths of the study lie in its size and the ability through national patient registry data to determine what medications the women took and who was diagnosed with hypertension over the nearly 35 years of follow-up.
The group struggled with the role postgestational chronic hypertension would play in the results. They opted to perform a mediation analysis that showed only about half of the association with later cardiomyopathy could be attributed to hypertension that followed the hypertensive disorder of pregnancy.
"The other half didn't appear to go through hypertension and so may actually be a direct effect of something to do with the pregnancy state itself or whatever common factor there is," she added. "So that was a potential limitation that I think we parlayed into a strength because we had these records."
The study was funded by the Danish Heart Association and the Danish Council for Independent Research. Dr Boyd reports no relevant financial relationships; disclosures for the coauthors are listed in the article.