While prenatal ultrasound screening detects a large number of cardiac abnormalities, the overall mortality remains high. Researchers call for better understanding of the natural history of congenital heart defects and improved screening programs, according to a study published in the February issue of Heart.
Jan Marek, MD, PhD, from University Hospital Motol in Prague, Czech Republic, and colleagues analyzed a Czech registry of all pediatric and fetal patients spanning 21 years.
Of the nearly 9,500 fetuses referred for detailed cardiac evaluation, 17 percent had congenital heart defects, of which 31 percent had additional extracardiac anomalies.
In the pregnancies which continued, 59 of 685 fetuses died in utero, and 626 babies were born alive. "Despite optimal delivery, management and expert treatment, another 147 children died later. As a result, only 479 (29.9 percent) of the 1,604 prenatally affected fetuses were alive at the end of the study," the researchers reported.
Marek and colleagues found that prenatal frequency of individual heart anomalies differed significantly from the postnatal frequency.
Postnatally, the most common cardiac lesion, ventricular septal defect (41 percent), was detected in only 9 percent of all prenatally examined heart lesions. Other differences included:
- Prenatal frequency of aortic stenosis at 4.9 percent versus postnatal frequency at 7.8 percent;
- Prenatal and postnatal frequency of transposition of the great arteries was equal at 5.4 percent;
- Prenatal frequency of hypoplastic left heart at 15 percent versus postnatal frequency at 3.9 percent;
- Prenatal frequency of atrioventricular septal defect at 15 percent versus postnatal frequency at 3.9 percent; and
- Prenatal frequency of double outlet right ventricle at 8.7 percent versus postnatal frequency at 1.1 percent.
Prenatal detection rate in the total cohort over 21 years was high in double outlet right ventricle (77 percent), hypoplastic left heart (50.6 percent ), Ebstein's anomaly (50 percent), atrioventricular septal defect (42.9 percent) and single ventricle (42.5 percent).
"In contrast, none of the fetuses with the isolated form of total anomalous pulmonary venous drainage and anomalous origin of left coronary artery from pulmonary trunk were diagnosed prenatally, and prenatal detection rate was low in atrial (0.8 percent) and ventricular (2.4 percent) septal defects and in pulmonary stenosis (3.2 percent)," the authors reported.
Marek and colleagues noted that the detection rate increased significantly for 12 of 17 lesions comparing 1986 to 1999 and 2000 to 2006.
In recent years, detection of hypoplastic left heart reached 96 percent, while transposition of the great arteries was diagnosed antenatally in only 25 percent.
"Despite the immense investment in this national prenatal cardiac screening program, the survival rate for the affected fetuses remained low with only one-third alive at the end of the study period. The high rate of associated extracardiac anomalies has a significant impact on the outcome of affected pregnancies," they concluded.
In addition, the researchers said, "We strongly believe that the centralization of fetal interventions into a limited number of well-equipped centers may help to better understand the natural history of obstructive cardiac lesions and to improve the results by optimizing risk management assessment, patient selection criteria and technique revalidation."