Does the Implantable Cardioverter-Defibrillator Benefit Vary With the Estimated Proportional Risk of Sudden Death in Heart Failure Patients?

BACKGROUND: Prediction of which heart failure patients are most likely to die of sudden death vs. non-sudden death is an important factor in determining who will benefit the most from an ICD.
OBJECTIVE: We developed the Seattle Proportional Risk Model (SPRM) to estimate the proportion of total mortality due to sudden death. We prospectively validated the model in HF-ACTION and tested whether the ICD benefit varied with the SPRM.
METHODS: Among 2331 patients enrolled, 1947 patients were retained for analysis over a median follow-up of 2.5 years. The SPRM was calculated using age, gender, diabetes, BMI, SBP, EF, NYHA, sodium, creatinine, and digoxin use.
RESULTS: ICD use (ICD or CRT-D) was present prior to death in 1204 patients (62%). SPRM was predictive of sudden death vs. non-sudden death in those without an ICD (P=0.002). The hazard ratio representing ICD versus no ICD was 0.63 for all-cause mortality (P=0.0002). The ICD benefit varied with the SPRM for all-cause mortality (P=0.001), with a greater benefit in those with a higher conditional probability of sudden death.
CONCLUSIONS: In an ambulatory NYHA II-IV HF population and EF ≤35%, the SPRM was predictive of the proportional risk of sudden vs. non-sudden death. ICDs were associated with a decreased risk of all-cause mortality by 37% and the ICD benefit varied with the SPRM. The SPRM may have utility in risk stratifying patients for a primary prevention ICD.