Discontinuation of Cardiac Resynchronization Therapy for Heart Failure Due to Dilated Cardiomyopathy in a 61-Year-Old Female "-Super-Responder" with Return of a Reduced Left Ventricular Ejection Fraction to Normal

BACKGROUND Although cardiac resynchronization therapy (CRT) is widely used, it has been validated only during active pacing. "Super-responders" are patients with normalized or markedly improved left ventricular (LV) systolic function with CRT who may experience a decline in cardiac function with CRT discontinuation. CASE REPORT A 61-year-old woman with a nonischemic cardiomyopathy was admitted to our hospital in September 2008 for the treatment of heart failure (HF). Cardiac assessment revealed impaired LV function with an ejection fraction of 18%, LV dilatation, and left bundle branch block (LBBB). Despite optimized medical treatment, her HF progressed, with a rapid increase in LV chamber size, mitral regurgitation, and widening of the QRS complex. In July 2011, the patient initially refused CRT, but later consented to the procedure; CRT pacemaker implantation was subsequently performed. Thereafter, the LVEF improved from 27% to 46%, LV diastolic dimension decreased rapidly from 79 mm to 56 mm, and LVEF (65%) and LV size (47 mm) normalized within 1 year later. As of August 2012, battery exchange was needed within 1 year because of high LV pacing thresholds. In October 2012, although CRT discontinuation was not recommended, we discontinued CRT to conserve battery life with the patient's consent, hoping to maintain her condition with pharmaceutical treatment. She remained stable through January 2020, with no indication of re-exacerbation. CONCLUSIONS We describe a female patient with a nonischemic cardiomyopathy and LBBB who demonstrated a super-response to CRT and maintained improvement in LV function and functional status for 8 years after discontinuing CRT.