Background: Implantable cardioverter-defibrillator (ICD) therapy is considered appropriate when a patient is felt to have a reasonable expectation of 1-year survival. Chronic diseases have been estimated to be associated with greater than 10% annual mortality and may reduce benefits of ICD therapy. Frailty has been estimated to be associated with greater than 20% annual mortality and has been suggested to contraindicate ICD therapy.

Purpose: Determine a risk score that may identify patients in whom ICD implantation may not be appropriate.

Methods: Patients who received an ICD for primary and secondary prevention from 2008 through 2013 at the Aurora Health Care network were studied retrospectively. Using Cox regression, a scoring system based on hazard ratios was devised to reflect risk associated with comorbidities. Survival was evaluated by Kaplan-Meier estimates.

Results: The study cohort includes 1,558 patients (mean age: 61.3 years; 495 female). Comorbidities associated with mortality included in the risk score were need for hemodialysis, myocardial infarct within 3 months prior to ICD implantation, sustained monomorphic ventricular tachycardia, New York Heart Association functional class III, age greater than 70 years, intraventricular conduction delay, diabetes mellitus, and chronic lung disease. A risk score of greater than or equal to 6 was associated with 10% mortality at 1 year and more than 20% mortality by 2 years.

Conclusion: Chronic comorbidities have a cumulative effect on mortality. Using our scoring system, patients with a risk score of 6 or greater have at least 10% mortality at 1 year and more than 20% mortality by 2 years.