The QT Interval Is Associated With Incident Cardiovascular Events: The MESA Study
Is the baseline QT interval predictive of negative cardiovascular outcomes?
The corrected QT interval (QTc) was measured in 6,273 subjects (mean age 61.7 years) without clinically apparent cardiovascular disease, who participated in the MESA (Multi-Ethnic Study of Atherosclerosis) study. The mean follow-up was 8 years. An incident cardiovascular event was defined as myocardial infarction (MI), resuscitated cardiac arrest, coronary heart disease-related death, stroke, or heart failure (HF).
The mean QTc was 411 ms. After adjustment for multiple risk factors and other confounding variables, each 10 ms increase in the baseline QTc was independently associated with incident HF (hazard ratio [HR], 1.25), cardiovascular disease (HR, 1.12), and stroke (HR, 1.19).
The authors concluded that QTc is an independent risk factor for negative cardiovascular outcomes in adults without clinically apparent cardiovascular disease.
Several prior studies that have examined the prognostic value of the QT interval have reported conflicting results. The present study provides additional evidence that the QTc is in fact a risk factor for negative outcomes in individuals without any obvious heart disease. The explanation for the prognostic value of the QT interval is unclear, but it is possible that the QT interval is a surrogate for sympathetic tone, and there are several lines of evidence suggesting that elevated sympathetic tone has atherogenic effects.
Keywords: Myocardial Infarction, Stroke, Confounding Factors (Epidemiology), Follow-Up Studies, Heart Failure, Risk Factors, Heart Arrest
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