The influence of sex on the beneficial effect of cardiac implantable electronic devices (CIEDs) has recently been appreciated, but remains poorly characterized. For example, implantable cardiac defibrillators (ICDs) may be less effective in women, whereas cardiac resynchronization therapy (CRT) defibrillators may be more effective. Importantly, women receive fewer implants than men in clinical practice and are underrepresented in clinical trials that evaluate CIEDs, making these questions difficult to answer.

Niraj Varma, MD, PhD, Cleveland Clinic, Cleveland, Ohio, USA, presented data from a retrospective study of sex-specific survival after a CIED implant. The purpose of the study was to use “big data” to characterize CIED utilization and postimplant mortality in women compared with men.

In this observational study, data from a cohort of 269 471 patients who received a CIED between 2008 and 2011 were evaluated for the primary outcome of all-cause mortality. CIEDs included pacemakers, ICDs, CRT pacemakers (CRT-P), and CRT defibrillators (CRT-D) from a single manufacturer. All devices were enabled with wireless remote monitoring, and all patients were followed for a minimum of 90 days. Patient demographics were accessed through the St Jude Medical device tracking database, and descriptive statistics were linked by patient ZIP code from the 2012 American Community Survey, which is administered by the US Census Bureau. Date of death was determined by the US Social Security Death Index Master File. The primary end point of all-cause survival was determined for each device type using unadjusted mortality incidence rates and adjusted Cox proportional hazards modeling stratified by age.

The mean age of the cohort was older than 70 years and two-thirds were men. Patients who received ICD implants were on average younger than patients implanted with other CIED devices. Across all device types, follow-up duration and remote monitoring utilization were comparable between sexes. The analysis revealed that a greater proportion of men received CIED implants across all device types. In particular, ICDs and CRT-Ds were implanted significantly less in women than in men. Survival was similar among men and women implanted with a pacemaker or ICD. Importantly, women who received CRT (CRT-D or CRT-P) experienced dramatically improved survival over men in the first 4 to 5 years post-CIED implant.

Dr Varma acknowledged that the limitations of this study included the limited clinical data available for a retrospective, observational analysis and the lack of a nondevice comparison group. However, he also noted that the strengths of the analysis were that it assessed a “real world” cohort of more than 200 000 patients and that it adds a large-scale evaluation of pacemaker and CRT-P patients.

Dr Varma concluded that this analysis suggests that women who receive a CRT-P or CRT-D have enhanced survival rates compared with men. In addition, women implanted with ICDs experienced similar survival rates as men. Therefore, strategies should be developed that ensure appropriate and full utilization of these devices in eligible women.