Published Online
on May 27, 2009

A more recent version of this article appeared on August 1, 2009

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Original Article

Clinical correlates and heritability of QT interval duration in African Americans: the Jackson Heart Study

Ermeg L. Akylbekova¹; Richard S. Crow²; William D. Johnson³; Sarah G. Buxbaum¹; Stephanie Njemanze⁴; Ervin Fox³; Daniel F. Sarpong¹; Herman A. Taylor³ and Christopher Newton–Cheh^5,6

¹ Jackson State University, Jackson, MS;
² University of Minnesota, Minneapolis, MN;
³ University of Mississippi Medical Center, Jackson, MS;
⁴ Wellesley College, Wellesley, MA;
⁵ Massachusetts General Hospital, Boston & Broad Institute of Harvard and MIT, Cambridge, MA

⁶ E-mail: cnewtoncheh{at}partners.org

Background—Electrocardiographic QT interval prolongation is a risk factor for sudden cardiac death (SCD) and drug–induced arrhythmia. The clinical correlates and heritability of QT interval duration in African Americans have not been well studied despite their higher risk for SCD compared to non–Hispanic whites. We sought to investigate potential correlates of the QT interval and estimate its heritability in the Jackson Heart Study (JHS).

Methods and Results—The JHS comprises a sample of African Americans residing in Jackson, Mississippi, of whom 5302 individuals with data at the baseline examination were available for study. JHS participants on QT–altering medications, with bundle branch block, paced rhythm, atrial fibrillation/flutter or other arrhythmias were excluded resulting in a sample of 4660 individuals eligible for analyses. The relation between QT and potential covariates was tested using multivariable stepwise linear regression. Heritability was estimated using SOLAR in a subset of 1297 JHS participants in 292 families; the remaining sample included unrelated individuals. In stepwise multivariable linear regression analysis, covariates significantly associated with QT interval duration included RR interval, female sex, QRS duration, age, lower potassium, hypertension, body mass index, coronary heart disease, diuretic use, and Sokolow-Lyon voltage (p 0.01 for all). The heritability of QT interval duration in age–, sex– and RR–interval–adjusted and fully–adjusted models was 0.41 (SE 0.07) and 0.40 (SE 0.07, p<10^-11 for both), respectively.

Conclusions—There is substantial heritability of adjusted QT interval in African Americans supporting the need for further investigation to identify its genetic determinants.

Key Words: death, sudden (if surviving, use heart arrest) • epidemiology • genetics • population • QT interval • Jackson Heart Study • heritability