Abstract 16286: Enhancement of Sudden Death Risk Stratification by Resting 12-Lead EKG Markers When Combined With LV Ejection Fraction: A Community-Based Study
Introduction: Abnormalities of repolarization and depolarization, as well as increased heart rate from the resting 12-lead EKG are associated with independently increased risk of sudden cardiac death (SCD). Could these contribute to SCD risk stratification when combined with LV ejection fraction measurements?
Methods: We conducted a case-control analysis of EKG parameters and LV ejection fraction from an ongoing population-based study of SCD in the Northwestern US. Cases with coronary artery disease (CAD) were compared to controls with CAD and no history of SCD. Analysis was limited to subjects age 18 or older with 12-lead EKG, prior to and unrelated to the acute event for case subjects. QRS duration (QRSd), PR interval and heart rate (HR) were obtained from recorded EKGs, while corrected QT (QTc, Bazett's correction) and Tpeak to Tend (TpTe) intervals were manually measured. ‘Abnormal EKG markers’ were defined as values greater than the fourth quartile in control subjects. Logistic regression was used to evaluate the association of SCD with presence of one, two or more ‘abnormal EKG markers’. A second model was employed to adjust for presence of severe LV systolic dysfunction (severe LVSD, EF ≤35%).
Results: A total of 353 cases and 342 controls with comparable age and gender distribution (p≥0.06) met criteria (2002-2009). Cases had significantly longer QRSd (101ms vs. 97ms), QTc (450ms vs. 428ms), TpTe (89ms vs. 76ms) intervals and higher HR (78ms vs. 68ms) compared to controls (p≤0.01). There was no case-control difference in the PR interval (p=0.25). Compared to subjects with no ‘abnormal EKG markers’ (AEM), those with 1 AEM had nearly 3-fold increased odds of SCD [OR 2.7 (1.6-4.5)]. Subjects with 2 AEM had 6-fold increased odds of SCD [OR 6.2 (3.6-10.5)]. Among subjects with a least three AEM, the odds of SCD were 9.6 (5.5-16.7). When combined with LV EF, these markers significantly increased predictive ability: for EF ≤35% plus 3 AEM, OR=20.9 (7.4-58.9).
Conclusions: Each additional abnormal EKG marker significantly increased the odds of SCD occurrence, especially when combined with the LV ejection fraction. These findings have implications for development of new approaches to SCD risk stratification.
- © 2011 by American Heart Association, Inc.