Design and implementation of a population-based registry of implantable cardioverter defibrillators (ICDs) in Ontario

Background — There are scarce population-based data on the use, complication rates, and outcomes of patients receiving implantable cardioverter defibrillators (ICDs).

Objective — This study sought to describe the methodology of the Ontario ICD Database, a prospective study of all ICD recipients in Ontario, Canada.

Methods — In this registry, web-based data collection will be performed in all patients referred to a cardiac electrophysiologist for consideration of an ICD. The variables included in the database were determined by consensus. Outcomes to be assessed will include defibrillator device therapies (e.g., shock or antitachycardia pacing), morbidity, and death. Preliminary statistics are reported after the first 6 months of data collection.

Results — Of 208 total variables selected by consensus, 111 (53.4%) were referral/patient characteristics, 12 (5.8%) were implant-related, and 85 (40.9%) were outcome variables. Among 990 referred patients, 902 were accepted, with the following ICD indications: primary prevention (63.3%), secondary prevention (21.6%), and generator replacement (15.1%). The mean (SD) age of patients with implants was 63.9 ± 12.6 years, and 79% were men. Among accepted ICD patients, 66% had ischemic heart disease, 23% had nonischemic dilated cardiomyopathy, and 11% had other cardiac conditions. Left ventricular (LV) systolic dysfunction was highly prevalent, with 82% of primary and 44% of secondary prevention patients having LV ejection fraction ≤30%. The perioperative complication rate was 3.69%.

Conclusion — The Ontario ICD Database will examine defibrillator patient characteristics and clinical and device-related outcomes. Contemporary ICDs are implanted largely for primary prevention, and the majority of these conformed with LV ejection fraction guidelines.