Sex differences in implantable cardioverter-defibrillator outcomes: findings from a prospective defibrillator database

Background — Sex differences in the use and outcomes of implantable cardioverter-defibrillators (ICDs) have not been fully studied.

Objective — To examine potential sex differences in ICD implantation and device outcomes.

Design — Health payer–mandated, prospective study of patients referred for ICD implantation, with comprehensive, longitudinal follow-up for complications, deaths, and device outcomes.

Setting — 18 ICD implantation and follow-up centers in Ontario, Canada.

Patients — 6021 patients (4733 men) referred for ICD implantation from February 2007 to July 2010.

Measurements — Multivariate-adjusted ICD implantation rate, complications up to day 45, multivariate-adjusted complications, device outcomes (including appropriate shocks and therapies), and deaths occurring during 1-year follow-up.

Results — Rates of ICD implantation were similar in men and women (relative risk, 0.99 [95% CI, 0.97 to 1.02];P_0.60). However, women were significantly more likely to experience major complications by 45 days (odds ratio, 1.78 [CI, 1.24 to 2.58];P_0.002) and 1 year (hazard ratio [HR], 1.91 [CI, 1.48 to 2.47];P_0.001) after implantation. Occurrence of any major or minor complication was also increased in women at both 45-day follow-up (odds ratio, 1.50 [CI, 1.12 to 2.00];P_0.006) and 1-year follow-up (HR, 1.55 [CI, 1.25 to 1.93];P_0.001). After implantation, women were less likely than men to receive appropriate ICD shock (HR, 0.69 [CI, 0.51 to 0.93];P_0.015) or appropriate therapy via shock or antitachycardia pacing (HR, 0.73 [CI, 0.59 to 0.90];P_0.003). Total mortality among defibrillator recipients did not differ between men and women (HR, 1.00 [CI, 0.64 to 1.55];P_0.99).

Limitation — The differential effects of sex on prereferral events were not examined.

Conclusion — Although defibrillator implantation rates were similar after referral to an electrophysiologist, women who underwent ICD implantation had greater risks for complications and were less likely to experience appropriate ICD-delivered therapies than men.