Researchers from the Cardiac Center at Children's Hospital of Philadelphia (CHOP) have presented new findings on congenital complete heart block (CCHB) at the American Heart Association's (AHA) Scientific Sessions 2020.
CCHB with a structurally normal heart is a rare diagnosis, seen in approximately 1 in 15,000 to 20,000 live births. Approximately 69% of patients with this diagnosis receive a pacemaker by their first birthday, and 74% to 96% receive a pacemaker by the time they are 20.
The condition is associated with an increased risk for left ventricular dysfunction, cardiomyopathy, heart failure and cardiac mortality, yet the most important risk factors for developing these complications are unknown.
To determine the incidence of complications among patients with CCHB and structurally normal hearts, as well as the demographic and clinical variables associated with morbidity and mortality, the researchers evaluated all patients with the condition seen at CHOP between January 1970 and April 2018. Subjects were excluded if they had structural congenital heart disease or genetic syndromes associated with declining heart function.
Analyzing 114 subjects diagnosed with CCHB over a more than 40-year period, 26 subjects (23%) had significant complications, including systolic dysfunction, heart failure, cardiomyopathy, cardiac resynchronization therapy, or death. Sex, diagnosis at less than one year of age, in utero diagnosis, and positive maternal antibody status did not have an associated significantly higher risk of these complications.
"We believe the importance of this investigation is that we were able to follow subjects with congenital complete heart block without structural heart disease over a 40-year period and describe the incidence of cardiac morbidity and mortality," said senior author Victoria L. Vetter, MD, cardiologist in the Cardiac Center at CHOP and Medical Director of Youth Heart Watch. "Although the sample size was relatively small, we believe these results compiled by our cardiology fellow, Dr. Scott Weinreb, are important for better understanding the risk factors associated with this condition."
