A Growing Problem: Maternal Death and Peripartum Complications Are Higher in Women with Grown-Up Congenital Heart Disease
Karamlou T, Diggs BS, McCrindle BW, Welke KF
Ann Thorac Surg 2011; 92: 2193–9
Reviewer: Nicole S. Wilder, MD, FAAP
University of Michigan C.S. Mott Children’s Hospital
This study is the first to report the national prevalence, diagnostic makeup, and peripartum outcomes of pregnant women with grown-up congenital heart disease (GUCH). It is estimated that the number of patients with GUCH is increasing at a rate of 5% per year with the number of GUCH parturients rising accordingly.1 Many previous analyses of this patient population have focused on single cardiac lesions and none have been powered to detect rare peripartum complications including maternal death. The Nationwide Inpatient Sample (NIS) is a stratified cross-sectional database that includes approximately 20% of non-Veterans Affairs hospital discharges in the United States. The investigators utilized this large administrative database to characterize peripartum morbidity and mortality for the national GUCH parturient population.
Methods:
The NIS was searched for all women undergoing delivery from 1998 to 2007. Women with GUCH were identified by the presence of a congenital cardiac diagnosis code (745-747.4) or by the specific NIS code for the presence of congenital heart disease in a parturient (648.5). Patient and hospital characteristics were compared between GUCH and non-GUCH patients. The primary outcomes were in-hospital maternal and fetal mortality. Secondary outcomes included preterm delivery, induction, cesarean section or surgically-assisted delivery, hospital length of stay, and maternal cardiac complications.
Results:
Of the 39.9 million births identified, 26,973 (0.07%) were among GUCH parturients. The non-GUCH delivery rate paralleled the US national birth rate, increasing 26% over the study period. GUCH deliveries, on the other hand, increased 43% over the same time period. Fifty-seven percent of GUCH parturients delivered at urban teaching hospitals, though nearly 10% delivered at rural hospitals. The most common defined congenital diagnoses were ventricular septal defect (VSD) (15%), aortic valvar pathology (12.7%), and atrial septal defect (ASD) (12.6%).
Estimated maternal mortality was 18-fold higher in GUCH parturients (0.09%) compared with non-GUCH parturients (0.005%) (p < 0.001). There was a non-significant trend towards higher maternal mortality among GUCH parturients in urban teaching hospitals (0.12%) versus non-teaching hospitals (0.06%). The rate of all peripartum complications studied was higher in the GUCH compared to the non-GUCH parturients. There was no difference in stillborn prevalence or hospital length of stay for the GUCH versus non-GUCH parturients. A diagnosis of VSD was associated with a higher prevalence of maternal mortality (40%), preterm delivery (11.2%), surgically-assisted birth (10.3%) and cesarean section (11.2%) compared with other known diagnostic subgroups (p < 0.05 for all).
GUCH parturients had a significantly higher prevalence of peripartum cardiac complications (2.3%) compared with non-GUCH parturients (0.2%) (p < 0.01). A diagnosis of ASD was associated with a trend toward higher cardiac complications than other known subgroups. The rate of cardiac complications among GUCH parturients was equivalent among teaching and nonteaching hospitals.
Comments:
This is a well-conducted review of a large administrative database which sheds light on the growing population of GUCH parturients. The study’s strength is the size of the database which allows examination of rare peripartum outcomes such as maternal mortality. The authors report that the study’s greatest limitations are due to the retrospective nature of an administrative database review. GUCH parturients who did not carry a viable fetus to delivery could not be identified. Of the GUCH parturients who were identified, over 40% had an “unknown cardiac diagnosis” and were excluded from analysis by outcome. Given the difficulty categorizing individuals with complex congenital cardiac repairs, including single ventricle palliation, it is possible that the sickest of the GUCH parturients were in the “unknown cardiac diagnosis” group. For the remaining GUCH parturients presenting for delivery with an identified congenital heart defect, there was no ability to differentiate between fully repaired, palliated, and unrepaired lesions.
The authors found an increased rate of maternal and peripartum complications in the VSD subpopulation when compared with other congenital defects in parturients. Increased pulmonary arterial pressures resulting from long-term pulmonary overcirculation in an unrepaired VSD could account for some of this. Pulmonary hypertension is a known risk factor in pregnancy and parturients with Eisenmenger’s syndrome have a mortality rate of 28% - 36%.2,3 Yap et al previously demonstrated a higher rate of pre-eclampsia in GUCH parturients with an unrepaired VSD compared with non-GUCH parturients and an increased risk of premature labor and small-for-gestational-age births in women with a repaired VSD compared with an unrepaired VSD.4 Additionally, Yap et al found an increased risk of neonatal events in GUCH parturients with an unrepaired versus repaired ASD and an increased risk of pre-eclampsia, small-for-gestational-age births, and fetal mortality in GUCH with an unrepaired ASD versus non-GUCH parturients.5
It is difficult to interpret the trend towards higher mortality rate for GUCH parturients in urban teaching hospitals compared with non-teaching institutions. One could speculate that the sicker patients were referred to the teaching hospitals but, without a measure of disease severity for each patient, no conclusions can be made.
Exclusion of the “unknown cardiac diagnosis” group in outcomes analysis almost certainly biases the analysis to underestimate the aggregate peripartum morbidity and mortality of the GUCH parturient population. It is disappointing that the authors of this retrospective outcomes study chose not to display their outcomes data in a table. By only mentioning key significant findings in the results section, the authors deprive the reader of the ability to contextualize the ‘significant’ findings in relation to the various subgroups, thus lessening their overall impact.
Conclusions:
Despite the study limitations, the authors should be commended for attempting to characterize our national GUCH parturient population whose numbers are increasing steadily as a result of improving pediatric congenital heart disease survivorship and relative functional health status. The increased morbidity and mortality in GUCH parturients with even uncomplicated lesions such as VSD and ASD highlights the need for increased education for all women with GUCH and their healthcare providers.
References:
- Williams RG, Pearson GD, Barst RJ, et al. Report on the National, Heart Lung, and Blood Institute Working Group on research in adult congenital heart disease. J Am Coll Cardiol 2006;47:701–7.
- Weiss BM, Zemp L, Seifert B. Outcome of pulmonary vascular disease in pregnancy: a systematic review from 1978 through 1996. J Am Coll Cardiol. 1998;31:1650–1657.
- Bédard E, Dimopulos K, Gatzoulis M. Has there been any progress made on pregnancy outcomes among women with pulmonary hypertension? Eur Heart J. 2009;30:256–265.
- Yap SC, Drenthen W, Pieper PG, et al. Pregnancy outcome in women with repaired versus unrepaired isolated ventricular septal defect. BJOG. 2010 May;117(6):683-9.
- Yap SC, Drenthen W, Meijboom FJ, et al. Comparison of pregnancy outcomes in women with repaired versus unrepaired atrial septal defect. BJOG 2009;116:1593– 601.
