Objective
To examine the association between prolongation of heart rate–corrected QT interval (QTc) with incident stroke.
Background
Unlike cardiovascular morbidity and mortality, little is known about the relationship between QTc and risk of stroke.
Methods
A total of 27,411 participants aged ≥ 45 years without prior stroke from the REasons for Geographic and Racial Differences in Stroke (REGARDS) study were included in this analysis. QTc was calculated using Framingham formula (QTcFram). Stroke cases were identified and adjudicated during up to 8.2 years of follow-up (median 5.1 years).
Results
The risk of incident stroke in study participants with prolonged QTcFram was almost three times the risk in those with normal QTcFram [HR (95% CI): 2.88 (2.12, 3.92), p<0.0001]. After adjustment for demographics (age, race, sex), traditional stroke risk factors (antihypertensive medication use, systolic blood pressure, current smoking, diabetes, left ventricular hypertrophy, atrial fibrillation, prior cardiovascular disease), warfarin use, aspirin use, QRS duration and use of QT-prolonging drugs, the risk of stroke remained significantly high [HR (95% CI): 1.67 (1.16, 2.41), p=0.0061)], and was consistent across several subgroups of REGARDS participants. Similar results were obtained when the risk of stroke was estimated per 1-standard deviation increase in QTcFram, [HR (95% CI): 1.12 (1.03, 1.21), p=0.0053 in multivariable-adjusted model], and when other QTc correction formulas including Hodge’s, Bazett’s and Fridericia’s were used.
Conclusions
QTc prolongation is associated with a significantly increased risk of incident stroke independent of traditional stroke risk factors. Examining the risk of stroke associated with QT-prolonging drugs may be warranted.