Risk Models for Prediction of Implantable Cardioverter-Defibrillator Benefit: Insights From the DANISH Trial

Abstract

Objectives: This study aims to identify patients with nonischemic heart failure who are more likely to benefit from implantable cardioverter-defibrillator (ICD) implantation by use of established risk prediction models.

Background: It has been debated whether an ICD for primary prevention reduces mortality in patients with nonischemic heart failure.

Methods: The Seattle Heart Failure Model (SHFM) predicts all-cause mortality whereas the Seattle Proportional Risk Model (SPRM) predicts the proportion of sudden cardiac death (SCD) versus nonsudden death, with a higher score indicating a greater proportion of SCD. We report the effect of ICD implantation on all-cause mortality and SCD, according to median SPRM and SHFM scores in all 1,116 patients enrolled in the DANISH (Danish study to Assess the Efficacy of ICDs in Patients with Non-ischemic Systolic Heart Failure on mortality) trial.

Results: Among patients with an SPRM score above the median (n = 558), ICD implantation reduced all-cause mortality (hazard ratio [HR]: 0.63; 95% confidence interval [CI]: 0.43 to 0.94), whereas patients with lower SPRM scores (n = 558) had no effect (HR: 1.08; 95% CI: 0.78 to 1.49, p for interaction = 0.04). The corresponding numbers for SHFM score above and below the median were HR: 0.84; 95% CI: 0.62 to 1.13 and HR: 0.82; 95% CI: 0.53 to 1.28, respectively (p for interaction = 0.980). In 177 patients with upper SPRM/upper SHFM, ICD implantation reduced all-cause mortality (HR: 0.45; 95% CI: 0.25 to 0.80) when compared to 381 patients with lower SPRM/upper SHFM (HR: 1.09; 95% CI: 0.76 to 1.55) (p for interaction <0.001).

Conclusions: Nonischemic heart failure patients with high predicted relative likelihood of SCD, as estimated by higher SPRM score, seemed to benefit from ICD implantation. (DANISH [Danish ICD Study in Patients With Ditaled Cardiomyopathy]; NCT00542945).

Keywords: implantable cardioverter-defibrillator; nonischemic cardiomyopathy; risk prediction.