Early Sudden Cardiac Death Risk in Heart Failure: Time to Rethink Primary Prevention?

Despite advances in drug and device-based therapies, patients with heart failure (HF) face a substantial risk for mortality. Sudden cardiac death (SCD) accounts for up to half of all deaths in patients with HF and reduced ejection fraction (HFrEF), with a 6- to 9-fold higher risk compared with the general population. Recent data demonstrate that the risk for arrhythmic events cluster disproportionately more frequently within the first ∼6 months following the diagnosis of HFrEF despite the initiation of guideline-directed medical therapy (GDMT). This period is characterized by electrical instability, neurohormonal activation, and incomplete reverse remodeling; this is exacerbated by suboptimal exposure to GDMT. While temporal analyses suggest an overall decline in SCD rates in patients with chronic HFrEF, a persistent residual SCD risk that is clinically meaningful remains. While pharmacologic therapies reduce the risk for SCD to varying degrees, structural recovery often lags, creating a vulnerable phase during GDMT up-titration. Current guidelines mandate a waiting period of at least 3-6 months prior to implantable cardioverter defibrillator (ICD) implantation to allow for potential ventricular recovery while GDMT is optimized. Moreover, the indication for primary prevention ICD implantation itself is being actively re-evaluated in the contemporary GDMT era. Yet this interval also exposes patients to an early arrhythmic risk, contributing to clinical apprehension. Wearable cardioverter defibrillators (WCD) may provide a noninvasive strategy to mitigate transient early SCD risk during guideline-mandated waiting periods. WCD platforms have demonstrated reliable arrhythmia detection and defibrillation capability, with high first-shock conversion rates and wear-time adherence in large-scale studies performed in clinical practice. WCDs enable continuous rhythm surveillance, which may support individualized decision-making regarding the timing of a permanent ICD implantation. This review synthesizes the contemporary burden and mechanisms of SCD in HFrEF and how approaches to primary prevention have evolved including an appraisal of the impact of GDMT on arrhythmic risk, current guideline recommendations, and examining the potential role of WCD therapy for protection during early phase vulnerability in these patients.