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Original Investigation
November 14, 2018

Association of African Ancestry With Electrocardiographic Voltage and Concentric Left Ventricular HypertrophyThe Dallas Heart Study

Author Affiliations
  • 1University of Texas Southwestern Medical School, Dallas
  • 2Division of Cardiology, Department of Internal Medicine, University of Texas Southwestern Medical School, Dallas
  • 3McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center, Dallas
  • 4Department of Radiology, University of Texas Southwestern Medical Center, Dallas
JAMA Cardiol. Published online November 14, 2018. doi:10.1001/jamacardio.2018.3804
Key Points

Question  Is there a genetic contribution to the increased electrocardiographic voltage and higher prevalence of concentric left ventricular (LV) hypertrophy in black vs white individuals?

Findings  In this cohort study including 2077 patients, genetically inferred proportion of African ancestry was associated with increased electrocardiographic voltage and measures of concentric LV hypertrophy as assessed by cardiac magnetic resonance imaging in multivariable models adjusting for age, sex, blood pressure, antihypertensive medication use, and body composition. These associations persisted in analyses restricted to black individuals only.

Meaning  These data support the possibility that genetic factors mediate, in part, the higher electrocardiographic voltage and predisposition to concentric LV remodeling and LV hypertrophy in black individuals compared with white individuals.

Abstract

Importance  Compared with white individuals, black individuals have increased electrocardiographic voltage and an increased prevalence of concentric left ventricular (LV) hypertrophy. Whether environmental or genetic factors lead to these racial differences is unknown.

Objective  To determine whether proportion of genetically determined African ancestry among self-reported black individuals is associated with increased electrocardiographic voltage and concentric LV hypertrophy (LVH).

Design, Setting, and Participants  The Dallas Heart Study is a probability-based cohort study of English- or Spanish-speaking Dallas County, Texas, residents, with deliberate oversampling of black individuals. Participants underwent extensive phenotyping, which included electrocardiography (ECG), cardiac magnetic resonance imaging (CMR), and dual-energy radiography absorptiometry (DEXA) at a single center. Participants aged 18 to 65 years who enrolled in the Dallas Heart Study between July 2000 and December 2002, self-identified as black (n = 1251) or white (n = 826), and had ECG, CMR, and DEXA data were included in this analysis. Data were analyzed from June 2017 to September 2018.

Exposures  Proportion of African ancestry.

Main Outcomes and Measures  Electrocardiographic voltage (12-lead and 9-lead) and markers of concentric LVH as assessed by CMR (LV concentricity0.67 [LV mass/end-diastolic volume0.67], LV wall thickness [LVWT], and prevalent LVH [defined by LV mass/height2.7]).

Results  Of the 2077 participants included in the study, 1138 (54.8%) were women, and the mean (SD) age was 45.2 (9.9) years. Black race and African ancestry were individually associated with increased ECG voltage, LV concentricity0.67, LVWT, and prevalent LVH in multivariable analyses adjusting for age, sex, systolic blood pressure, antihypertensive medication use, and body composition. When African ancestry and black race were entered together into multivariable models, African ancestry but not black race remained associated with ECG voltage, LVWT, LV concentricity0.67, and prevalent LVH. Among black participants, African ancestry remained associated with these 4 phenotypes (12-lead voltage: β, 0.05; P = .04; LVWT: β, 0.05; P = .02; LV concentricty0.67: β, 0.05; P = .045; prevalent LVH: odds ratio, 1.2; 95% CI, 1.03-1.4; P = .02).

Conclusions and Relevance  Genetically determined African ancestry was associated with electrocardiographic voltage, measures of concentric LV remodeling, and prevalent LVH. These data support a genetic basis related to African ancestry for the increased prevalence of these cardiovascular traits in black individuals.

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