Primary Prevention Implantable Cardioverter-Defibrillator Therapy in Heart Failure with Recovered Ejection Fraction

Recovery From Left Ventricular Dysfunction

The treatment of heart failure is an evolving field of cardiology, with increasingly available therapeutics and significant disease burden. With the effective treatments available, we see a substantial patient population whose once reduced ejection fraction (EF) has normalized. Studies have assessed the natural history of these patients with improved EF and found improved mortality as compared with those patients with persistently reduced EF, with some evidence stating that each 5% increase in left ventricular EF correlates with a 4.9-fold decrease in the odds of mortality. This prognostic divergence has led to the recognition of this subset of patients as having a unique heart failure diagnosis, distinct from heart failure with reduced EF (HFrEF) or heart failure with preserved EF and to the adoption of the term heart failure with recovered EF. These patients, despite having improved mortality, do retain some of the molecular and histologic changes seen in HFrEF and are still at risk for decline in left ventricular function and adverse cardiac events, particularly when medical therapy is stopped. This distinction between recovery of EF and true myocardial recovery led to recent guidelines recommending continuation of guideline-directed medical therapy indefinitely, as well as surveillance echocardiography.

Heart failure with improved ejection fraction: Beyond diagnosis to trajectory analysis

Left ventricular (LV) systolic dysfunction represents a highly treatable cause of heart failure (HF). A substantial proportion of patients with HF with reduced ejection fraction (EF;HFrEF) demonstrate improvement in LV systolic function (termed HF with improved EF [HFimpEF]), either spontaneously or when treated with guideline-directed medical therapy (GDMT). Although it is a relatively new HF classification, HFimpEF has emerged in recent years as an important and distinct clinical entity. Improvement in LVEF leads to decreased rates of mortality and adverse HF-related outcomes compared to patients with sustained LV systolic dysfunction (HFrEF). While numerous clinical and imaging factors have been associated with HFimpEF, identification of which patients do and do not improve requires further investigation. In addition, patients improve at different rates, and what determines the trajectory of HFimpEF patients after improvement is incompletely characterized. A proportion of patients maintain improvement in LV systolic function, while others experience a recrudescence of systolic dysfunction, especially with GDMT discontinuation. In this review we discuss the contemporary guideline-recommended classification definition of HFimpEF, the epidemiology of improvement in LV systolic function, and the clinical course of this unique patient population. We also offer evidence-based recommendations for the clinical management of HFimpEF and provide a roadmap for future directions in understanding and improving outcomes in the care of patients with HFimpEF.