Abstract 18512: Left Ventricular Diameter Adds Prognostic Value to Ejection Fraction in Risk Stratification for Sudden Cardiac Death
Introduction: Current approaches to risk stratification for sudden cardiac death (SCD) rely almost exclusively on the left ventricular (LV) ejection fraction (EF). LV size is routinely measured in the echocardiogram but has not been considered in risk assessment.
Hypothesis: We assessed the hypothesis that consideration of LV diameter improves SCD risk assessment in those with low EF.
Methods: From a large ongoing, population-based study of SCD in a metro region of the Northwestern US (population approximately 1 million), SCD cases age ≥ 18 years with echocardiograms available prior (but unrelated) to the SCD event were compared with population-based controls. Severe LV dysfunction (LVD) was defined as EF ≤ 35%. LV size, measured using the LV internal dimension in diastole (LVIDD), was categorized as normal, mild, moderate or severe dilatation using American Society of Echocardiography (ASE) recommended cut-offs. Case-control comparisons were performed using the t-test or chi-square test and multiple logistic regression.
Results: Case subjects (n=418) were slightly older than controls (n=329) (69.5 ± 13.8 vs. 67.7 ± 11.9; p=0.06), were more likely to be African American (11.8% vs 4.2%; p < 0.001), and more commonly had severe LVD (30.5 % vs. 18.8%; p=0.001). The mean LV size (52.2 ± 10.5 mm vs. 49.7 ± 7.9 mm; p < 0.001 ) and LV size index adjusted for body surface area (BSA) (26.6 ± 5.3 mm/m2 vs. 25.4 ± 4.2 mm/m2; p = 0.001) were significantly higher in cases. Moderate or severe LV dilatation (16.3% vs. 8.2%; p = 0.001) and severe LV dilatation (8.1% vs. 2.1%; p < 0.001) were significantly more likely to be observed in cases. In multivariable logistic regression, severe LV dilatation was an independent predictor of SCD (OR 2.5; 95% CI 1.03-5.9; p=0.04), adjusting for age, black race and low EF. Subjects with both low EF and severe LV dilatation had an OR for SCD of 3.8 (1.5-10.2) while for those with only low EF, the OR was 1.7 (1.2-2.5) suggesting that severe LV dilatation additively increased the risk of SCD.
Conclusions: Increased LV diameter adds incremental prognostic value to LVEF in risk prediction for SCD in the community; this readily available echocardiographic measure warrants further evaluation.
- © 2013 by American Heart Association, Inc.