The Ability Of Ecg Risk Variants To Predict Sudden Arrhythmic Death In Asymptomatic Middle-Aged Subjects Without A Known Cardiac Disease

Background: Numerous traditional and novel risk markers in standard 12-lead electrocardiogram (ECG) have been associated with increased risk of sudden arrhythmic death syndrome (SADS) in general population. However, in asymptomatic subjects without a known cardiac disease the actual clinical impact of these ECG risk markers is unknown. We investigated the predictive power of the ECG risk markers for SADS in asymptomatic middle-aged subjects. Methods: We evaluated 12-lead ECGs of 10009 asymptomatic Finnish middle-aged subjects without a known cardiac disease (51.6% men, mean age 43±8.3) with a follow-up of 30±11 years. The end point was SADS according to CAST criteria. ECG variables associated with an increased risk for SADS, such as prolonged intraventricular conduction delay (IVCD) >110 msec, left bundle branch block (LBBB), abnormal QRS angle, inverted T waves in leads other than V1-V3, prolonged QTc interval, inferior early repolarization (ER) ECG pattern and/or pathological Q waves were considered as abnormal ECGs. The risk of SCD was compared between the subjects with any ECG abnormality and those without abnormal ECG. Results: Prevalence of subjects with abnormal ECG was 8.7% (N=871). The strongest predictors of SADS were LBBB (relative risk [RR] 3.2, 95% CI 1.2-8.4), IVCD (RR 3.1, 95% CI 1.6-6.0), T-inversion (RR 3.0, 95% CI 1.5-6.0), abnormal QRST angle (RR 2.9, 95% CI 1.9-4.5), pathological Q-waves (RR 2.6, 95% CI 1.6-4.3), prolonged QTc (RR 2.6, 95% CI 1.9-3.5), and inferior ER (RR 2.2, 95% CI 1.6-3.2). IVCD, abnormal QRS angle, pathological Q-waves, prolonged QTc duration and inferior early repolarization remained as independent risk factors of SCD in Cox multiple regression analysis after adjusting for several other risk variables (p Conclusions: The prevalence of abnormal ECG increasing the risk of SADS is substantial in asymptomatic middle-aged subjects. Future studies using more rigorous statistics, such as c-statistics, reclassification and cost-effectiveness analyses, will reveal the impact of routine ECG screening of middle-aged subjects for SADS.