BACKGROUND
Heart failure patients with primary prevention implantable cardioverter-defibrillators (ICD) may experience an improvement in left ventricular ejection fraction (LVEF) over time. However, it is unclear how LVEF improvement affects subsequent risk for mortality and sudden cardiac death (SCD).
OBJECTIVES
We sought to assess changes in LVEF after ICD implantation and the implication of these changes on subsequent mortality and ICD shocks.
METHODS
We conducted a prospective cohort study of 538 patients with repeated LVEF assessments after ICD implantation for primary prevention of SCD. The primary endpoint was appropriate ICD shock, defined as a shock for ventricular tachyarrhythmias. The secondary endpoint was all-cause mortality.
RESULTS
Over a mean follow-up of 4.9 years, LVEF decreased in 13.0%, improved in 40.0%, and was unchanged in 47.0% of the patients. In the multivariate Cox models comparing patients with an improved LVEF to those with an unchanged LVEF, the hazard ratios were 0.33 (95% confidence interval [CI]: 0.18 to 0.59) for mortality and 0.29 (95% CI: 0.11 to 0.78) for appropriate shock, respectively. During follow-up, 25% of patients showed an improvement in LVEF to >35% and their risk of appropriate shock decreased but was not eliminated.
CONCLUSION
Among primary prevention ICD patients, 40.0% had an improved LVEF during follow-up and 25% had LVEF improved to >35%. Changes in LVEF were inversely associated with all-cause mortality and appropriate shock for ventricular tachyarrhythmia. In patients whose follow-up LVEF improved to >35%, the risk of an appropriate shock remained but was markedly decreased.