QRS-T angle as a predictor of sudden cardiac death in a middle-aged general population

Spatial QRS-T angle measured from a 12-lead electrocardiogram (ECG) has been shown to predict cardiac mortality. However, there is a paucity of studies on the prognostic significance of frontal QRS-T angle, which is more readily available from the standard 12-lead ECG. The purpose of the present study was to investigate the importance of wide frontal QRS-T angle, QRS-axis, and T-wave axis as cardiac risk predictors in general population. We evaluated the 12-lead ECGs of 10 957 Finnish middle-aged subjects from the general population recorded between 1966 and 1972, and followed them for 30 11 years. QRS-T angle 0 to 90, QRS-axis 30 to 90, and T-wave axis 0 to 90 were considered normal. The primary endpoint was death from arrhythmia, and the secondary endpoints were all-cause mortality and non-arrhythmic cardiac mortality. QRS-T angle epsilon 100 was present in 2.0 of the subjects, and it was associated with an increased risk of sudden arrhythmic death [relative risk (RR) 2.26; 95 confidence interval (CI) 1.593.21; P 0.001) and all-cause mortality (RR 1.57; CI 1.341.84; P 0.001), but not with non-arrhythmic cardiac mortality (RR 1.34; CI 0.931.92; P 0.13). The prognostic significance of wide QRS-T angle was mainly due to abnormal T-wave axis, which predicted death from arrhythmia (RR 2.13; CI 1.632.79; P 0.001), all-cause mortality (RR 1.39; 1.241.55; P 0.001), and non-arrhythmic cardiac death (RR 1.87; CI 1.502.34; P 0.001). Frontal QRS-T angle epsilon 100 increases the risk of arrhythmic death, this being mainly the result of an altered T-wave axis.