Abstract 10969: Intraventricular Conduction Delay in 12-lead Electrocardiogram Predicts Sudden Cardiac Death in General Population
Background: Prolonged duration of QRS complex (QRSd) in 12-lead electrocardiogram (ECG) is associated with adverse prognosis in patients with cardiac disease, but its significance is not well established in general population samples. Right bundle branch block (RBBB) is usually considered as a benign finding, but some studies suggest that left bundle branch block (LBBB) associates with higher risk of cardiac death. There are paucity of studies assessing the prognostic significance of non-specific intraventricular conduction delay (IVCD) in ECG in apparently healthy subjects. Therefore, we studied the prognostic significance of increased QRSd and IVCD in a large community-based general population.
Methods: We evaluated 12-lead ECGs of 10899 Finnish middle-aged subjects from general population (52% males, mean age 44±8.5 years), and followed them for 30±11 years. Primary end points were cardiac mortality, all-cause mortality, and arrhythmic death. Prolonged QRSd was defined as QRS ≥ 110ms, with subgroups of complete or incomplete bundle branch blocks and IVCD (defined as QRS > 110ms without the criteria of complete or incomplete bundle branch block). Relative risks were adjusted for age, sex and differences in the baseline characteristics between groups.
Results: QRSd ≥ 110ms was present in 1,3% (n=147) and IVCD 0.4% (n=42) of the subjects. QRSd ≥ 110ms predicted all-cause mortality (adjusted relative risk [RR] 1.48; 95% confidence interval [CI] 1.22–1.81; P<0.001), cardiac mortality (RR 1.94; CI 1.44–2.63; P<0.001), and sudden arrhythmic death (RR 2.14; CI 1.38–3.33; P=0.002). Subjects with IVCD had an increased risk of death from any cause (RR 1.99; CI 1.39–2.86; P<0.001), an elevated risk of death from cardiac causes (RR 2.59; CI 1.49–4.49; P=0.003), and a markedly elevated risk of death from arrhythmia (RR 4.12; CI 2.18–7.77; P<0.001). LBBB was a significant predictor of arrhythmic death (RR 2.71; CI 1.20–6.11; P=0.04) but not of cardiac or all-cause mortality. RBBB was not associated with adverse outcome.
Conclusion: In general middle-aged population, QRSd ≥ 110ms is associated with increased mortality. In this population, especially IVCD in 12-lead ECG increases mortality and carries up to 4-fold risk of sudden cardiac death.
- © 2010 by American Heart Association, Inc.