A Risk Portrait: Women With Congenital Heart Disease Giving Birth

Marcia Frellick

April 13, 2017

SAN FRANCISCO, CA — Researchers who studied millions of births from women with and without congenital heart disease found that those with such disorders were more likely to have cesarean delivery, arrhythmias, a history of congestive heart failure, longer hospital stays, and more readmissions[1].

In their report published April 12, 2017 in JAMA Cardiology, Dr Robert M Hayward (University of California, San Francisco [UCSF]) and colleagues identified 3,702,838 live births from the Healthcare Cost and Utilization Project's California State Inpatient Database from 2005 to 2011, which represented 98.4% of all live births in California in that period.

Of those, 3189 women had noncomplex and 262 had complex congenital heart disease. Researchers compared maternal and fetal outcomes for both groups and among congenital heart disease categories.

The large study made it possible to get a clearer look at the implications of delivery in women with congenital heart disease, which is often studied in cohorts of perhaps only several dozen, senior author Dr Zian Tseng (UCSF) told heartwire from Medscape.

"We looked at the kitchen sink—heart failure, preeclampsia, outcomes of the baby, fetal growth restriction, and subsequent hospitalization," he said.

Pregnancy and delivery for women with congenital heart disease are "generally safe, and serious events were rare (0.5% or less)," Tseng said. "But the rate is still much higher than for women without congenital heart disease. The absolute risk is low but the relative risk is high."

Among the group's findings: Women with congenital heart disease were more likely than those without to have cesarean delivery (39.3% vs 32%; P<0.001).

"We don't know what the chicken and the egg are here," Tseng said. "But the code for intrauterine fetal distress, meaning a code that would necessitate a more urgent cesarean delivery, was not more common in women with congenital heart disease. So it suggests that the higher rate of cesareans among women with congenital heart disease is probably by choice."

Complex congenital heart disease was associated with ventricular arrhythmias and death of the mother in the hospital, although the events were rare (fewer than 10 women each with noncomplex or complex congenital heart disease).

As the authors describe, complex congenital heart disease in the analysis included endocardial cushion defects, hypoplastic left heart syndrome, tetralogy of Fallot, transposition of the great arteries, truncus arteriousus, and univentricular heart defects. All other forms were considered noncomplex.

The odds ratio (OR) was increased for fetal growth restriction among mothers with noncomplex (OR 1.6, 95% CI 1.3–2.0) and complex (OR 3.5, 95% CI, 2.1–6.1) congenital heart disease.

Combined, the two congenital-disease groups showed more than three times the risk for hospital readmission (OR 3.6, 95% CI 3.3–4.0). Congenital heart disease was a stronger predictor of readmission than diabetes, chronic kidney disease, or hypertension, according to the report.

Tseng said the readmission finding was surprising. "What that tells me is that doctors may want to follow women with congenital heart disease more closely as an outpatient after delivery to monitor their status and hopefully prevent readmission."

History of heart failure was more common when women had congenital heart disease: 7.3% in women with complex congenital heart disease; 3.5% in women with noncomplex congenital heart disease; and 0.1% in women without congenital heart disease (P<0.001).

Women with congenital heart disease also had longer length of stay than women without (mean 3 vs 2 days; P<0.001). Also, 11.1% of the women with complex congenital heart disease and 6% of those with noncomplex congenital heart disease stayed in the hospital more than 7 days, compared with only 1.3% of women without congenital heart disease.

Tseng said that although complications are rare, the team recommends delivery in an adult congenital heart disease center where a congenital heart disease expert can team up with an obstetrician to monitor patients and prevent serious complications.

In an invited commentary[2], Dr William R Davidson (Pennsylvania State University, Hershey) notes that by looking at the outcomes through an insurance database, the authors avoid the referral bias of studying patients in an adult congenital heart disease center.

"For the first time, a more accurate measure of absolute risk is available," he writes.

Medical advances in the past few decades mean more people with congenital heart disease are living to mature ages, and they want the same life options as the general population, Davidson notes. "Hayward and colleagues have provided an improved prospective on pregnancy risk for investigators and reassuring news for many women with [congenital heart disease] desiring to bear a child."

This study tracked women only at delivery, but Davidson wonders, "How many patients were unnecessarily advised to avoid pregnancy? How many patients were unnecessarily advised to have a safe pregnancy terminated?"

Women with congenital heart disease need regular counseling on contraception, assessment of pregnancy risk, and optimal timing of pregnancy relative to medical procedures, he writes.

Hayward has received educational travel grants from Medtronic and Boston Scientific. Tseng has received minor honoraria from Biotronik. The other authors and Davidson have disclosed no relevant financial relationships.

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