Isolated pre-existing ischemic heart disease (IHD) in pregnancy is associated with worse outcomes at the time of delivery compared with patients with no cardiac diagnosis, with a level of risk similar to  that associated with World Health Organization (WHO) class I-II cardiac diagnoses, according to a study published Dec. 14 in JACC: Advances.

Anna E. Denoble, MD, MSCR, et al., conducted a retrospective cohort study using data collected from

2015 to 2018 in the Nationwide Readmissions Database (NRD) to compare adverse pregnancy outcomes between those with isolated IHD and those with other cardiac diagnoses in the modified WHO classification (mWHO) and those without a cardiac diagnosis. The mWHO classification of maternal cardiovascular risk is widely used to counsel patients with pre-existing cardiac disease during pregnancy but does not include IHD.

Results showed that of 11,556,136 hospitalizations for delivery, IHD alone was identified in 3,009 and other cardiac diagnoses in 63,331. Patients with IHD were older and had higher rates of diabetes and hypertension.

Unadjusted analyses showed that adverse outcomes were more common among patients with isolated IHD. After adjustment, the risk of a primary outcome event, defined as severe maternal morbidity (SMM) or death during the delivery hospitalization, was higher among patients with IHD alone (adjusted relative risk [aRR]), 1.51; 95% CI, 1.19-1.92) vs. those without cardiac disease. Furthermore, the aRR was 1.90 for WHO class I-II diseases and 5.87 for WHO II/III-IV diseases.

Patients with isolated IHD were also at higher risk for nontransfusion SMM or death (aRR, 1.60) and cardiac SMM or death (aRR, 2.98).

The authors note that, to their knowledge, this is the largest analysis to date examining the risk of severe morbidity and mortality among pregnant people with IHD. The relative risk of SMM and mortality IHD compared with patients with no cardiac disease was similar with that for cardiac lesions classified as mWHO class I or II, suggesting that an IHD diagnosis should be considered for addition to mWHO class I or II to further refine the classification schema, and that these “data will aid clinicians in counseling patients with pre-existing IHD.”

Clinical Topics: Cardiovascular Care Team

Keywords: Counseling, World Health Organization, Heart Diseases, Morbidity, Myocardial Ischemia, Risk Factors, Patient Readmission, Cardiovascular Diseases, Retrospective Studies, Female, Pregnancy

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