Interrelationship between electrocardiographic left ventricular hypertrophy, QT prolongation, and ischaemic stroke: the REasons for Geographic and Racial Differences in Stroke Study.
OBJECTIVE
To determine if the association between electrocardiographic left ventricular hypertrophy (ECG-LVH) and ischaemic stroke is partially explained by the concomitant presence of QT prolongation.


RESULTS
A total of 24 948 (mean age = 65 ± 9.4 years; 40% black; 55% women) participants from the REasons for Geographic And Racial Differences in Stroke (REGARDS) study were included in this analysis. Electrocardiographic left ventricular hypertrophy was defined by the Sokolow-Lyon criteria. Heart rate-adjusted QT (QTa) was computed using a linear regression model. Adjudicated ischaemic stroke events were the outcome of interest. Cox regression was used to compute hazard ratios (HRs) and 95% confidence intervals (CIs) for associations between ECG-LVH and prolonged QTa, in isolation and combined, with ischaemic stroke. There were 2422 (9.7%) participants with ECG-LVH, 820 (3.3%) with prolonged QTa, and 161 (0.6%) with both. Over a median follow-up of 7.6 years, 714 (2.9%) ischaemic stroke events occurred. After adjustment for stroke risk factors and potential confounders, an increased risk of ischaemic stroke was observed among participants with ECG-LVH and prolonged QTa (HR = 1.85, 95% CI = 1.04-3.30), isolated ECG-LVH (HR = 1.40, 95% CI = 1.13-1.75), and isolated prolonged QTa (HR = 1.45, 95% CI = 1.04-2.03) compared with participants without either condition. When ECG-LVH and prolonged QTa were examined as separate variables, the risk of ischaemic stroke for each condition remained statistically significant.


CONCLUSIONS
The combination of ECG-LVH and prolonged QT is associated with a higher risk of ischaemic stroke compared with either condition in isolation, and the stroke risk for each condition does not depend on the presence of the other.
Department of Internal Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA woneal@wakehealth.edu.
Wesley T
WT
O'Neal
Department of Epidemiology, School of Public Health, University of Alabama at Birmingham, Birmingham, AL, USA.
Virginia J
VJ
Howard
Department of Neurology, University of Cincinnati, Cincinnati, OH, USA.
Dawn
D
Kleindorfer
Department of Neurology, University of Cincinnati, Cincinnati, OH, USA.
Brett
B
Kissela
Department of Biostatistics, School of Public Health, University of Alabama at Birmingham, Birmingham, AL, USA.
Suzanne E
SE
Judd
Department of Biostatistics, School of Public Health, University of Alabama at Birmingham, Birmingham, AL, USA.
Leslie A
LA
McClure
Department of Medicine, University of Vermont, Burlington, VT, USA.
Mary
M
Cushman
Department of Biostatistics, School of Public Health, University of Alabama at Birmingham, Birmingham, AL, USA.
George
G
Howard
Department of Internal Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA Epidemiological Cardiology Research Center (EPICARE), Department of Epidemiology and Prevention, Wake Forest School of Medicine, Winston-Salem, NC, USA.
Elsayed Z
EZ
Soliman
D000368:Aged; D001145:Arrhythmias, Cardiac / Q000453:epidemiology* / Q000503:physiopathology*; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate; D006801:Humans; D017379:Hypertrophy, Left Ventricular / Q000453:epidemiology* / Q000503:physiopathology*; D053208:Kaplan-Meier Estimate; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D012307:Risk Factors; D020521:Stroke / Q000453:epidemiology* / Q000503:physiopathology*; D014481:United States
Left ventricular hypertrophy; QT interval; Stroke