Hypertension during pregnancy linked to severe cardiovascular events

Hypertension during pregnancy linked to severe cardiovascular events | Image Credit: © Chinnapong - © Chinnapong - stock.adobe.com.

There is a relationship between hypertensive disorders of pregnancy (HDP) and cardiovascular severe maternal morbidity (cvSMM), according to a recent study published in JAMA Network Open.¹

Severe maternal morbidity (SMM) is the incidence of adverse outcome associated with pregnancy, labor, childbirth, and the postpartum period. These outcomes lead to severe illness and may cause long-term disability.

An increase in SMM rates has been observed in the United States, leading the World Health Organization to recommend SMM prevention efforts.² Cardiovascular complications have also increased, with a rate of up to 8 per 10,000 delivery hospitalizations.¹

Data on cvSMM, which refers to severe cardiovascular morbidity during pregnancy, is also necessary, as cardiovascular complications are the leading cause of pregnancy-related deaths in high-income settings. Preventative measures may be implemented once characterization of cvSMM has been improved.

Approximately 10% of pregnancies are impacted by HDP, with rates increasing in North America and worldwide. Therefore, determining the link between HDP and cvSMM may allow for improved resource allocation.

To evaluate the association between HDP and cvSMM, investigators conducted a population-based cohort study. Hospital discharge data was obtained from the National Inpatient Sample in the United States and included patient-level demographics, diagnoses, and procedures.

Participants included pregnant patients aged 12 to 55 years with an obstetric delivery between October 1, 2015, and December 31, 2019. American College of Obstetricians and Gynecologists 2013 criteria was used to define HDP.

HDP exposure was reported based on severity and included gestational hypertension, chronic hypertension without preeclampsia, preeclampsia without severe features, severe preeclampsia, and hemolysis, elevated liver enzymes, and low platelets (HELLP) syndrome.

Cardiovascular types of SMM as defined by the Centers for Disease Control and Prevention (CDC) were used to report cvSMM as the primary outcome. Examples of cvSMM included aneurysm, acute myocardial infarction, conversion of cardiac rhythm, cardiac arrest, heart failure, pulmonary edema, puerperal cerebrovascular disorders, and shock.

All SMM was reported as the secondary outcome using a larger CDC algorithm. Data was coded based on the International Statistical Classification of Diseases, Tenth Revision, Clinical Modification.

There were 15,714,940 obstetric deliveries reported, 13.02% of which were complicated by HDP. Patients who were Black, with an annual household income under $39,000, and aged at least 40 years were more likely to experience HDP.

Participants with HDP had increased rates of prepregnancy diabetes, gestational diabetes, and obesity, at 3.6%, 11.82%, and 23.55%, respectively. In patients without HDP, these rates were 0.76%, 6.99%, and 8.79%, respectively.

Similarly, rates of chronic ischemic heart disease and cardiomyopathy were higher in patients with HDP at 0.19% and 0.12%, respectively, vs 0.05% and 0.03%, respectively, in those without HDP. Cesarean delivery was reported in 43.63% of patients with HDP vs 30.2% without HDP.

SMM was reported in 1.8% of overall deliveries and cvSMM in 0.15%. An approximately 5-fold increase in the cvSMM rate was reported in patients with HDP vs those without HDP, with rates of 0.48% and 0.10%, respectively. Pulmonary edema and cerebrovascular disorders were reported more often than other cvSMM cases.

Significant increases in acute myocardial infarction, aneurysm, cardiac arrest, conversion of cardiac rhythm, puerperal cerebrovascular disorders, pulmonary edema, and shock rates were observed among HDP patients vs non-HDP patients. Links with cvSMM during delivery hospitalizations were reported for all HDP subtypes.

The greatest association with cvSMM was identified for HELLP syndrome, with an adjusted risk ratio (RR) of 17.55. This was followed by severe preeclampsia with an adjusted RR of 9.11 and chronic hypertension with an adjusted RR of 3.37.

These results indicated an association between all HDP subtypes and cvSMM events. Investigators concluded there is an “urgent need for improved peripartum cardiovascular care in the short-term, in addition to efforts focused on long-term cardiovascular risk reduction.”

References

1. Malhamé I, Nerenberg K, McLaughlin K, Grandi SM, Daskalopoulou SS, Metcalfe A. Hypertensive disorders and cardiovascular severe maternal morbidity in the US, 2015-2019. JAMA Netw Open. 2024;7(10):e2436478. doi:10.1001/jamanetworkopen.2024.36478
2. ChouD, TunçalpÖ, FirozT,et al; Maternal morbidity working group. Constructing maternal morbidity - towards a standard tool to measure and monitor maternal health beyond mortality.BMC Pregnancy Childbirth. 2016;16(1):45. doi:10.1186/s12884-015-0789-4