Ventricular Arrhythmias in Super-responders to Cardiac Resynchronization Therapy

A B S T R A C T Introduction and objectives: Cardiac resynchronization therapy is associated with improved quality of life and reduced morbidity and mortality in patients with severe ventricular dysfunction and wide QRS. However, its role in the reduction of ventricular arrhythmias is more controversial. Methods: We compared the incidence of ventricular arrhythmias in patients who were undergoing cardiac resynchronization therapy with an implantable cardioverter-defibrillator in terms of the degree of echocardiographic response to resynchronization. Patients were classified in 3 subgroups; super- responders, responders, and nonresponders. Results: We included 196 patients who were followed up for a median 30.1 months (interquartile range, 18.0-55.1 months). We recorded the presence of ventricular arrhythmias in 37 patients (18.8%); 3 patients (5.9%) in the super-responder group had ventricular arrhythmias vs 14 (22.2%) among the responders and 20 (24.4%) in the group of nonresponders (P = .025). In multivariate analysis, the only independent predictors of the appearance of ventricular arrhythmias were secondary-prevention device implantation (odds ratio = 4.04; 95% confidence interval, 1.52-10.75; P = .005), absence of echocardiographic super-response (odds ratio = 3.81; 95% confidence interval, 1.04-13.93; P = 043), QRS >160 ms (odds ratio = 2.39; 95% confidence interval, 1.00-1.35; P = .049) and treatment with amiodarone (odds ratio = 2.47; 95% confidence interval, 1.03-5.91; P = .041). Conclusions: The patients classified as super-responders to cardiac resynchronization therapy had a significant reduction in incidence of ventricular arrhythmias by comparison with the other patients. Despite this, arrhythmic episodes do not completely disappear in this subgroup.