BACKGROUND:
Although sex differences exist in the use of ICDs, reasons for the disparities are poorly understood. We determined if age, comorbid conditions, or ICD indication explained the sex differences.
METHODS:
We examined all patients in Ontario, Canada, with cardiac arrest (CA, 1998 –2007), myocardial infarction (MI, 2002–2007), or heart failure (HF, 2005–2007), using the Canadian Institute for Health Information Database. MI and HF cohorts excluded those with prior CA, and included patients post-MADIT-2 and SCD-HeFT trials. Patients were followed until ICD implant using Cox regression, with hazard ratio (HR) >1.0 indicating greater likelihood of ICD implant in men.
RESULTS:
Among 9246 patients eligible for ICD implantation after CA, 237 (2.6%) women and 725 (7.8%) men received ICDs. In 105,516 primary prevention MI patients, 172 (0.2%) women and 836 (0.8%) men received ICDs. Among 61,160 primary prevention HF patients, 221 (0.4%) women and 852 (1.4%) men received ICDs. The rate of ICD implant was significantly higher in men across indications adjusting for age, prior arrhythmia, and comorbidities (Figure
). Post-CA, the HR for secondary prevention ICD was 1.92 (95%CI, 1.66 –2.23). Men were more likely to undergo ICD implant than women for primary prevention, with HRs 3.00 (95%CI, 2.53–3.55) post-MI and 3.01 (95%CI, 2.59 –3.50) in HF patients. Although death after primary prevention ICD did not differ by sex, mortality risk was higher in men after CA (HR 1.42; 95%CI, 1.03–1.95).
CONCLUSIONS:
Differences in ICD use for all indications were not explained by age or comorbidities. Despite increased use, men had reduced post-implant survival after cardiac arrest.
Use of Primary Prevention Implantable Cardioverter-Defibrillators in a Population-Based Cohort Is Associated With a Significant Survival Benefit