Prognostic value of frontal QRS-T angle in patients without clinical evidence of cardiovascular disease (from the Multi-Ethnic Study of Atherosclerosis)

Abnormal frontal QRS-T angle on a 12-lead electrocardiogram is associated with incident coronary heart disease and total mortality in a biracial cohort, but there have been no studies to date examining QRS-T angle's prognostic value across multiple ethnicities. We studied 6,814 participants (52.7% women, mean age 62 years) from Multi-Ethnic Study of Atherosclerosis, a multiethnic cohort aged 45 to 84 years free of clinical cardiovascular disease (CVD) at enrollment. Baseline examination included measurement of traditional risk factors and 12-lead electrocardiograms. Frontal QRS-T axis was defined as normal (less than seventy-fifth percentile), borderline (seventy-fifth to ninety-fifth percentile), or abnormal (ninety-fifth percentile or more), and participants were followed for the composite end point of incident CVD events: cardiovascular death, myocardial infarction, angina pectoris, or heart failure. After 7.6 years of follow-up, there were 444 total events. Borderline (HR [hazard ratio] 1.37, 95% confidence interval [CI] 1.10 to 1.70) and abnormal QRS-T angles (HR 2.2, 95% CI 1.63 to 2.97) were associated with incident CVD events in multivariate-adjusted models. However, after adjusting for T-wave abnormalities, there was no statistically significant association of either borderline (HR 1.12, 95% CI 0.90 to 1.41) or abnormal (HR 1.31, 95% CI 0.93 to 1.84) QRS-T angle with incident CVD events. Abnormal frontal QRS-T angle predicts incident CVD events in a multiethnic population, and this increased risk is primarily mediated through T-wave abnormalities. QRS-T angle provides an easily interpretable continuous marker of abnormal ventricular repolarization that can aid the everyday clinician in risk prediction.