Added Value of 3- Versus 2-Dimensional Echocardiography Left Ventricular Ejection Fraction to Predict Arrhythmic Risk in Patients With Left Ventricular Dysfunction

OBJECTIVES: The study sought to evaluate the potential clinical impact of using 3-dimensional echocardiography (3DE) to measure left ventricular ejection fraction (LVEF) in patients considered for implantable cardioverter-defibrillator (ICD) implantation and to assess the predictive value of 3DE LVEF for arrhythmic events. BACKGROUND: ICD therapy is currently recommended to prevent sudden cardiac death in patients with symptomatic heart failure and LVEF ≤35%, and in asymptomatic patients with ischemic heart disease and LVEF ≤30%. Two-dimensional echocardiography (2DE) is currently used to calculate LVEF. However, 3DE has been reported to be more reproducible and accurate than 2DE to measure LVEF. METHODS: The study prospectively enrolled 172 patients with LV dysfunction (71% ischemic). Both 2DE and 3DE LVEF were obtained during the same study. The outcome was the occurrence of major arrhythmic events (sudden cardiac death, aborted cardiac arrest, appropriate ICD therapy). RESULTS: After a median follow up of 56 (range 18 to 65) months, major arrhythmic events occurred in 30% of the patients. Compared with 2DE, 3DE changed the assignment above or below the LVEF thresholds for ICD implantation in 20% of patients, most of them having 2DE LVEFs within ± 10% from threshold. By cause-specific hazard model, 3DE LVEF was the only independent predictor of the occurrence of major arrhythmic events. CONCLUSIONS: LVEF by 3DE was an independent predictor of major arrhythmic events and improved arrhythmic risk prediction in patients with LV dysfunction. When compared with 2DE LVEF, 3DE measurement of LVEF may change the decision to implant an ICD in a sizable number of patients.