Women with preexisting ischemic heart disease without another cardiac diagnosis have a higher risk of severe maternal morbidity and mortality than women with no cardiac disease, a new study suggests.
However, after adjustment for other comorbidities, the risk associated with isolated preexisting ischemic heart disease without additional evidence of cardiomyopathy was relatively similar to that of other low-risk cardiac diseases.
“These are reassuring findings,” lead author of the study, Anna E. Denoble, MD, Yale University School of Medicine, New Haven, Connecticut, told theheart.org | Medscape Cardiology.
“The risk is not zero. Women with preexisting ischemic heart disease are at a small increased risk compared to women without preexisting cardiac disease. But with good control of cardiovascular risk factors, these women have a good chance of a positive outcome,” she added.
The study was published online in JACC: Advances on December 14.
“To our knowledge, this study provides the largest analysis to date examining the risk of severe morbidity and mortality among pregnant people with pre-existing ischemic heart disease,” the authors note.
Denoble, a maternal and fetal medicine specialist, explained that in recent years, there has been an increase in the number of patients with preexisting ischemic heart disease who are considering pregnancy or who are pregnant when they present, but there is little information on outcomes for these patients.
The diagnosis of ischemic heart disease is not included in the main classification used for heart disease in pregnancy ― the modified World Health Organization (mWHO) classification, Denoble noted. “This classification includes information on pregnancy outcomes in women with many cardiac conditions, including arrhythmias, congenital heart disease, heart failure, and aortic aneurysm, but ischemic heart disease is missing.”
She suggested that this is probably because ischemic heart disease is regarded as a condition that occurs mainly in older people. “But we are seeing more and more women with ischemic heart disease who are pregnant or considering pregnancy. This could be because women are now often older when considering pregnancy, and also risk factors for ischemic heart disease, such as obesity and diabetes, are becoming more frequent in younger women.”
The researchers conducted the current study to investigate pregnancy outcomes for these women.
The retrospective cohort study analyzed data from the Nationwide Readmissions Database on women who had experienced a delivery hospitalization from October 1, 2015, to December 31, 2018. They compared outcomes for women with isolated preexisting ischemic heart disease to those of women who had no apparent cardiac condition and to those with mild or more severe cardiac conditions included in the mWHO classification after controlling for other comorbidities.
The primary outcome was severe maternal morbidity or death. Denoble explained that severe maternal morbidity includes mechanical ventilation, blood transfusion, and hysterectomy ― the more severe maternal adverse outcomes of pregnancy.
Results showed that of 11,556,136 delivery hospitalizations, 65,331 patients had another cardiac diagnosis, and 3009 had ischemic heart disease alone. Patients with ischemic heart disease were older, and rates of diabetes and hypertension were higher.
In unadjusted analyses, adverse outcomes were more common among patients with ischemic heart disease alone than among patients with no cardiac disease and mild cardiac conditions (mWHO class I-II cardiac disease).
Of those with preexisting ischemic heart disease, 6.6% experienced severe maternal morbidity or death, compared to 1.5% of those without a cardiac disease (unadjusted relative risk compared to no cardiac disease, 4.3; 95% CI, 3.5 – 5.2).
In comparison, 4.2% of women with mWHO I-II cardiac diseases and 23.1% of those with more severe mWHO II/III-IV cardiac diseases experienced severe maternal morbidity or death.
Similar differences were noted for nontransfusion severe maternal morbidity and mortality, as well as cardiac severe maternal morbidity and mortality.
After adjustment, ischemic heart disease alone was associated with a higher risk of severe maternal morbidity or death compared to no cardiac disease (adjusted relative risk [aRR], 1.51; 95% CI, 1.19 – 1.92).
In comparison, the aRR was 1.90 for WHO class I-II diseases and 5.87 (95% CI, 5.49 – 6.27) for more severe cardiac conditions defined as WHO II/III-IV diseases.
Risk for nontransfusion severe maternal morbidity or death (aRR, 1.60) and cardiac severe maternal morbidity or death (aRR, 2.98) were also higher for those with ischemic heart disease than for women without any cardiac disease.
There were no significant differences in preterm birth for those with preexisting ischemic heart disease compared to those with no cardiac disease after adjustment.
The risk of severe maternal morbidity and mortality, nontransfusion severe maternal morbidity and mortality, and cardiac severe maternal morbidity and mortality for ischemic heart disease alone most closely approximated that of mWHO class I or II cardiac diseases, the researchers say.
“We found that individuals with preexisting ischemic heart disease had a rate of severe maternal morbidity/mortality in the same range as those with other cardiac diagnoses in the mild cardiac disease classification (class I or II),” Denoble commented.
“This prognosis suggests it is very reasonable for these women to consider pregnancy. The risk of adverse outcomes is not so high that pregnancy is contraindicated,” she added.
Denoble said this information will be very helpful when counseling women with preexisting ischemic heart disease who are considering pregnancy. “These patients may need some extra monitoring, but in general, they have a high chance of a good outcome,” she noted.
“I would still advise these women to register with a high-risk obstetrics provider to have a baseline cardiovascular pregnancy evaluation. As long as that is reassuring, then further frequent intensive supervision may not be necessary,” she said.
However, the authors point out, “It is important to communicate to patients that while pregnancy may be considered low risk in the setting of pre-existing ischemic heart disease, 6.6% of patients with pre-existing ischemic heart disease alone did experience severe maternal morbidity or death during the delivery hospitalization.”
They add that other medical comorbidities should be factored into discussions regarding the risks of pregnancy.
The researchers also note that the study was limited to evaluation of maternal outcomes occurring during the delivery hospitalization and that additional research that assesses rates of maternal adverse cardiac events and maternal morbidity occurring prior to or after the delivery hospitalization would be beneficial.
Future studies examining the potential gradation in risk associated with additional cardiac comorbidities in individuals with preexisting ischemic heart disease would also be worthwhile, they add.
The study was supported by funding from the National Institutes of Health and the Foundation for Women and Girls with Blood Disorders. The authors have disclosed no relevant financial relationships.
JACC Adv. Published online December 14, 2022. Full text