Plasticity of left ventricular function with cardiac resynchronization therapy

Purpose To evaluate the clinical and echocardiographic effects of prolonged cessation and resumption of left ventricular pacing among patients with chronic cardiac resynchronization therapy (CRT). Methods This was a retrospective analysis of patients with long-term CRT who had loss of left ventricular pacing because of battery depletion. Clinical assessment and echocardiographic data were analyzed with comparisons between implant, chronic CRT, loss of CRT, and after resumption of CRT. Results There were 7 CRT responders who underwent 8 successful pulse generator replacements due to loss of CRT 6.3 +/- 2.3 months after reaching elective replacement interval. With initial CRT implantation, QRS duration decreased from 171 +/- 25 to 145 +/- 28 ms (P < 0.001) and left ventricular ejection fraction increased from 27.6 +/- 8.1 to 53.9 +/- 9.6% (P < 0.001). At pulse generator replacement, worsening heart failure was present 6 of 7 patients with significant deterioration of left ventricular function and the left ventricular ejection fraction decreased to 43.4 +/- 8.4%(P = 0.001). After resumption of CRT, clinical status and cardiac function recovered with left ventricular ejection fraction increasing to 53.7 +/- 8.7% (P = 0.001). Conclusions Prolonged loss of CRT is associated with significant deterioration of left ventricular function and functional status that is fully reversible with resumption of left ventricular pacing.