Abstract 18679: A Novel Volumetric Index of Left Ventricular Sphericity Independently Predicts Appropriate ICD Therapy
Introduction: Adverse left ventricular (LV) remodeling plays an important role in arrhythmogenesis of patients with abnormal systolic function, but it is unknown if noninvasive parameters associated with adverse remodeling predict arrhythmias in the real-world population. In this retrospective study, we sought to determine if a novel echocardiographic index of LV remodeling would predict appropriate implantable cardioverter-defibrillator (ICD) therapy in patients who received primary prevention ICDs with and without cardiac resynchronization therapy (CRT-D).
Methods: We determined the sphericity index (SI), the ratio of biplane LV end-diastolic volume to apical 4-chamber LV end-diastolic length, and examined its association with appropriate ICD therapy for ventricular arrhythmias in primary prevention patients receiving ICDs between 2006 and 2010.
Results: We studied 278 subjects (203 - conventional ICD, 75 - CRT-D). Median follow-up (f/u) was 2.0 and 2.1 years, respectively. Appropriate ICD therapy occurred in 28 (18.7%) of the patients with ICDs and 15 (20.0%) of the patients with CRT-Ds. Median time to first appropriate ICD therapy was significantly shorter in patients with SI in the upper vs. lower 50% of values (1.43 vs. 2.40 years, p=0.01 for the ICD cohort; 1.54 vs. 2.63 years, p=0.04 for the CRT-D cohort). In multivariable Cox regression analysis, an SI in the upper 50% (>2.61 ml/mm for the ICD cohort; >2.65 ml/mm for the CRT-D cohort) was a strong independent predictor of appropriate ICD therapy after adjustment for gender, age, New York Heart Association functional class, LV ejection fraction, BUN, and atrial fibrillation (adjusted Hazard Ratio [HR] 2.0, p=0.03 for the ICD cohort; adjusted HR 5.4, p=0.015 for the CRT-D cohort). An SI in the upper 50% was not associated with total mortality in either cohort.
Conclusions: Echocardiographic SI predicts appropriate ICD therapy, but not total mortality, in patients with primary prevention ICDs. Prospective study of SI is warranted to confirm its clinical value for risk stratifying patients.
Author Disclosures: J. Matos: None. Y.C. Levine: None. W.J. Manning: None. A.E. Buxton: None.
- © 2014 by American Heart Association, Inc.