Objective To assess differences in clinical outcome of implantable cardioverter-defibrillator (ICD) treatment in men and women.

Design Prospective cohort study.

Setting University Medical Center.

Patients 1946 primary prevention ICD recipients (1528 (79%) men and 418 (21%) women). Patients with congenital heart disease were excluded for this analysis.

Main outcome measures All-cause mortality, ICD therapy (antitachycardia pacing and shock) and ICD shock.

Results During a median follow-up of 3.3 years (25th–75th percentile 1.4–5.4), 387 (25%) men and 76 (18%) women died. The estimated 5-year cumulative incidence for all-cause mortality was 20% (95% CI 18% to 23%) for men and 14% (95% CI 9% to 19%) for women (log rank p<0.01). After adjustment for potential confounding covariates all-cause mortality was lower in women (HR 0.65; 95% CI 0.49 to 0.84; p<0.01). The 5-year cumulative incidence for appropriate therapy in men was 24% (95% CI 21% to 28%) as compared with 20% (95% CI 14% to 26%) in women (log rank p=0.07). After adjustment, a non-significant trend remained (HR 0.82; 95% CI 0.64 to 1.06; p=0.13).

Conclusions In clinical practice, 21% of primary prevention ICD recipients are women. Women have lower mortality and tend to experience less appropriate ICD therapy as compared with their male peers.