Abstract 2033: Increased Complexity of ST-T Waves in Body Surface Potential Mapping Predicts Arrhythmic Events after Myocardial Infarction and Cardiac Dysfunction
Background: Increased heterogeneity of ventricular repolarization is associated with arrhythmia propensity in various cardiac pathologies. We investigated if repolarization heterogeneity manifesting as ST-T wave complexity in body surface potential mapping (BSPM) predicts major arrhythmic events (MAE = sudden cardiac death or sustained ventricular arrhythmia) in post-infarction patients with cardiac dysfunction.
Methods: Patients (n=158, males 129) with acute myocardial infarction (MI) and cardiac dysfunction were studied. Mean age was 61 ± 9 years and left ventricular ejection fraction (LVEF) 40 ± 6%. A 120 lead BSPM was performed 1–4 weeks after MI. After signal averaging of 150–250 beats at rest a principal component analysis was applied to each ST-T wave recorded in each patient. ST-T wave complexity was calculated as the relative information content of the first principal component (CO 1). Also, the relative information content of the first three principal components (CO 1–3) was calculated.
Results: During a mean follow-up of 50 months 30 patients died and 16 had a MAE (10 sustained ventricular arrhythmias and 6 sudden cardiac deaths). Both CO 1 (57 ± 9 vs. 65 ± 10%, p=0.005) and CO 1–3 (87± 4 vs. 90 ± 4%, p=0.003) were smaller in patients with MAEs. Using the mean minus 1 SD of the non-arrhythmia patients as the cut-point value both parameters were significant predictors of MAEs in univariate analysis (CO 1: log-rank 4.9, p=0.03 and CO 1–3: log-rank 11.3, p<0.001). Also in multivariate analysis including age, sex, LVEF, atrial fibrillation, bundle branch block, and diabetes both parameters were independent predictors of MAEs (CO 1: hazard ratio 2.8, p=0.04 and for CO 1–3 hazard ratio 4.7, p= 0.002). Neither of the parameters was associated with all-cause mortality.
Conclusion: In post-infarction patients with cardiac dysfunction heterogeneity of ventricular repolarization displayed as increased complexity of ST-T waves in body surface potential mapping is a significant predictor of major arrhythmic events.