Heart failure with recovered ejection fraction and the utility of defibrillator therapy: a review

Heart failure with recovered ejection fraction (HFrecEF) involves those who have previously had reduced cardiac function that has subsequently improved. However, there is not a single definition of this phenomenon and recovery of cardiac function in terms of left ventricular ejection fraction (LVEF) itself does not necessarily correlate with remission from the detrimental physiology of heart failure (HF) and its consequences. There is also the question of the utility of defibrillators in these patients, and whether they should be replaced at the time of battery depletion. To address this, several studies have shown specific predictors of ensuing LVEF recovery, including patient demographics, co-morbidities, and medication use, as well as predictors of ventricular arrhythmias (VA) following LVEF recovery. Recent studies have also shown novel imaging parameters that may aid in predicting which patients would have a higher risk of these arrhythmias. Additional data describe a small, yet appreciable risk of VA, in addition to appropriate shocks as well. In this review, we describe predictors of LVEF recovery, carefully analyse and characterize the continued risk for VA and appropriate shocks following LVEF recovery, and explore additional novel modalities that may aid in decision-making.