Persistent improvement of ejection fraction in patients with a cardiac resynchronisation therapy defibrillator correlates with fewer appropriate ICD interventions and lower mortality

Cardiac resynchronisation therapy with defibrillator back-up (CRT-D) is a well-established treatment option for selected heart failure patients. Left ventricular ejection fraction (LVEF), an important risk determinant of life-threatening arrhythmias, can substantially ameliorate with CRT. Our hypothesis was that patients with LVEF improvement to >40% have a lower arrhythmic risk and fewer appropriate defibrillator therapies beyond year one.

In this retrospective analysis, all 175 patients with CRT-D implanted from February 2000 to June 2011 and follow-up of >2 years were identified. Every available echocardiography recording was collected. LVEF measurements were grouped to baseline and yearly intervals (±6 months). All appropriate defibrillator therapies were considered events.

Age at implant was 65 ± 10 years, 86% were male, and 45% patients had ischemic cardiomyopathy. Follow-up was 5.5 ± 2.6 years. LVEF at implant was 25 ± 6%, increased to 34 ± 12% after one year and remained stable thereafter. 39% (69) of patients experienced a sustained increase of LVEF to ≥40%, 14% of them had tachyarrhythmic events (versus 42.5% in those without such increase). Independent predictors for increase were higher baseline LVEF (HR 1.08 (95%-CI 1.04-1.28) per 1% increase) and lack of amiodarone (HR 0.37, 95%-CI 0.16-0.84). With cut-off values of >40%, >45% and >50%, the study hypothesis was refuted in 7%, 2.5% and 5%, respectively. Cumulative 5-year survival was 95% in improvers versus 73% in non-improvers (p <0.001).

After CRT-D implantation, mean LVEF increased to >40% in 1/3 of patients. These patients experienced significantly fewer arrhythmias during long-term follow-up when compared to patients with persisting LVEF <40%.