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

Abstract

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 ICD 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.

Primary funding source: Canadian Institutes of Health Research and Ontario Ministry of Health and Long-Term Care.