Inequitable distribution of implantable cardioverter defibrillators in Ontario

Implantable cardioverter defibrillator (ICD) therapy reduces the risk of sudden death in patients with ischemic cardiomyopathy, but their novelty and cost may represent barriers to utilization. The objective of this study was to examine the influence of age, gender, place of residence, and socioeconomic status on rates of ICD implantation for the primary prevention of death.

We conducted a population-based retrospective cohort study involving the entire province of Ontario, Canada. Patients were eligible if they had survived following hospitalization for heart failure from 1 January 1993, to 31 March 2004, and previously sustained an acute coronary syndrome within 5 years. Patients with an existing ICD or a documented history of cardiac arrest were excluded, as were patients who died in the hospital. Primary outcome was ICD implantation.

We identified 48,426 patients hospitalized for heart failure who survived to hospital discharge. Of these, 440 received an ICD, with a gradual 30-fold increase in implantation rates over the study period (.12-3.9 percent). ICD recipients were more likely to be men (odds ratio [OR]=4.14; 95 percent confidence interval [CI], 3.24-5.30), younger than 75 years of age (OR=3.19; 95 percent CI, 2.57-3.96), reside in a metropolitan area (OR=1.42; 95 percent CI, 1.04-1.9), and live in a higher socioeconomic neighborhood (OR=1.32; 95 percent CI, 1.08-1.61).

Among patients with heart failure and a previous myocardial infarction, ICD use is increasing in Ontario. However, the application of this technology is characterized by major sociodemographic inequities. The causes and consequences of the pronounced age and gender discrepancies, in particular, warrant further investigation.