Objectives: The purpose of this study was to determine the frequency and causes of intermittent and permanent loss of cardiac resynchronization therapy (CRT) in patients who have undergone the successful implantation of a transvenous defibrillator that delivers CRT (CRT-D).
Background: The causes of loss of CRT have not been described.
Methods: The records of 512 patients who underwent an attempt at implantation of a transvenous CRT-D device as part of the VENTAK CHF/CONTAK CD Biventricular Pacing study were analyzed.
Results: Device implantation was successful in 443 of 512 (87%) of patients. Among these 443 patients, CRT was interrupted in 161 (36%) patients during a mean follow-up of 2.5 +/- 1.1 years. Reasons included the development of an atrial tachyarrhythmia (18%), loss of left ventricular capture (10%), diaphragmatic stimulation (2%), loss of right ventricular capture (2%), infection (1%), intentional discontinuation of CRT (1%), loss of right atrial sensing (1%), and ventricular oversensing (0.2%). Most patients underwent an intervention that permitted the reinstitution of CRT, such that only 20 of the 443 patients (5%) experienced the permanent loss of CRT. Using an intention-to-treat analysis, the long-term retention of CRT was 83% during the course of 2.5 years.
Conclusions: Cardiac resynchronization therapy is interrupted in more than one-third of patients after the successful implantation of a CRT-D device. However, CRT can be reinstituted in most patients and has a high long-term retention rate. Because patients with slower heart rates were more likely to develop atrial tachyarrhythmias, a dual-chamber rate-modulated pacing mode (DDDR) may reduce interruptions of CRT.