Predictors of primary prevention implantable cardioverter-defibrillator use in heart failure with reduced ejection fraction: impact of the predicted risk of sudden cardiac death and all-cause mortality

Aims Use of implantable cardioverter-defibrillators (ICD) for primary prevention of sudden cardiac death (SCD) in heart failure with reduced ejection fraction (HFrEF) is limited. We aimed to investigate barriers to ICD use in HFrEF while considering the predicted risk of mortality and SCD. Method and results Patients from the SwedeHF registered in 2011-2018 and with an indication for primary prevention ICD were analysed. The Seattle Proportional Risk and Seattle Heart Failure Models were used to predict the proportional SCD and all-cause mortality risk, respectively. A multivariable logistic regression model was fitted to identify independent predictors of ICD use/non-use; Cox regression models to evaluate the interaction between predicted SCD/mortality risk and ICD use for mortality. Of 13 475 patients, only 15.5% had an ICD. Those with higher predicted proportional SCD risk (>45%) had an similar to 80% higher likelihood to have an ICD. Other predictors of non-use were follow-up in primary versus specialty care, higher comorbidity burden and lower socioeconomic status. ICD use was associated with lower mortality only in patients with higher predicted SCD and lower mortality risk (34% and 37% relative risk reduction for 3-year all-cause and cardiovascular mortality, respectively). In this subgroup of patients, underuse of ICD was 81.8%. Conclusion In a contemporary registry, only 15.5% of patients with an indication for primary prevention ICD received the device. While a high predicted proportional SCD risk was appropriately linked to ICD use, the lack of specialized follow-up, higher comorbidity burden, and lower socioeconomic status were major unjustified impediments to implementation. Our findings suggest areas for improving ICD use for primary prevention of SCD in clinical practice.