Abstract 16416: Wide QRS-T Angle on the 12-lead ECG as a Predictor of Sudden Death Beyond the LV Ejection Fraction

Introduction: If we are to improve risk stratification for sudden cardiac death (SCD) we should extend beyond the LV ejection fraction (LVEF). The frontal QRS-T angle has been shown to predict risk of SCD but its value independent of LVEF has not been investigated. Hypothesis: We hypothesize that a wide frontal QRS-T angle predicts SCD independent of LVEF. Methods: Cases of adult sudden cardiac arrest with an available electrocardiogram before the event were identified from a large ongoing population based study of SCD in the Northwest US (population approx. one million). Subjects with a computable frontal QRS-T angle were included. A total of 686 SCD cases (mean age 67.4 years; 95% CI, 52.5 to 82.3 years; 68.2% males; 83.5% whites) met criteria, and were compared to 871 controls with and without coronary artery disease (mean age 66.8 years, 55.3 to 78.3 years; 67.7% males; 90.6% whites) from the same geographical region. Results: The mean frontal QRS-T angle was higher in SCD cases (73.9 degrees; 95% CI, 17.5 to 130.3 degrees, p<0.0001) compared to controls (51.1 degrees; 95% CI 5.0 to 97.2 degrees). Using a cut-off of more than 90 degrees, the frontal QRS-T angle was predictive of SCD, and remained predictive, after adjusting for age, sex, left ventricular ejection fraction (LVEF), prolonged QTc, prolonged QRS duration and baseline comorbidities (OR 1.80; 95% CI, 1.27 to 2.55, p=0.001). On the receiver operating characteristic (ROC) curve, the QRS-T angle demonstrated an area-under-curve (AUC) value of 0.614. Compared to the lowest quartile of QRS-T angle, the highest quartile had nearly a triple increase in the risk of SCD (OR 2.71; 95% CI; 2.03 to 3.60; p<0.0001). Conclusion: A wide QRS-T angle greater than 90 degrees is associated with increased risk of sudden cardiac death independent of left ventricular ejection fraction.