Sex differences in implantable cardioverter-defibrillator outcomes: findings from a prospective defibrillator database
MacFadden DR, Crystal E, Krahn AD, Mangat I, Healey JS, Dorian P, Birnie D, Simpson CS, Khaykin Y, Pinter A, Nanthakumar K, Calzavara AJ, Austin PC, Tu JV, Lee DS. Ann Intern Med. 2012; 156(3):195-203.
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.