Comparison of the prevalence of first-degree atrioventricular block in African-American and in Caucasian patients: an electrocardiographic study III.

BACKGROUND: Electrocardiographic (ECG) differences occur between African-American and Caucasian patients.
METHODS: The study includes ECGs of 2,123 patients, ages 20-99 years attending an urban hospital.
RESULTS: First-degree atrioventricular (AV) block was more prevalent in African-American patients compared with Caucasian patients in all age groups of the study except for those patients in the eighth decade of life. The prevalence of first-degree AV block began to increase at age 50 years in both ethnic groups and gradually increased with advancing age, peaking in African-American patients in the 10th decade of life, and in Caucasian patients in the ninth decade of life. The continuing increase in first-degree AV block in African-American patients in the 10th decade of life suggests increasing impairment but greater durability of the AV conduction system in African-American compared with Caucasian patients. The dramatic decline of the prevalence of first-degree AV block in Caucasian patients in the 10th decade of life suggests more frequent failure of the AV conduction system in this group of patients at ages 90-99 years, compared with African-American patients in the same age group. In population-based surveys, first-degree AV block was more prevalent in African-American subjects compared with Caucasian subjects.