Women Receive Far Fewer CIEDs Than Men but Have Higher Survival Rates After Implant

Deborah Brauser

June 29, 2015

MILAN, ITALY — Women are being short-changed when it comes to receiving cardiac implantable electronic devices (CIEDs), which is especially concerning because they actually have higher survival rates than men after implantation of certain device types, suggests new research[1].

A "big-data" retrospective, US-wide cohort study of nearly 270,000 patients with a CIED showed that although men received more permanent pacemakers (PPMs) and cardiac resynchronization therapy pacemakers (CRT-Ps) than women, the numbers were statistically similar. However, women received only about one-fourth of the implantable cardioverter defibrillators (ICDs) and cardiac resynchronization therapy defibrillators (CRT-Ds).

In addition, women had significantly improved long-term survival rates after receiving either type of CRT device compared with men.

"In clinical practice, fewer women receive these devices and in CIED clinical trials, women are being consistently underrepresented," lead author Dr Niraj Varma (Cleveland Clinic, OH) told attendees during a late-breaking trial session at the European Heart Rhythm Association (EHRA) EUROPACE-CARDIOSTIM 2015 meeting.

"Development of strategies to ensure appropriate and full utilization of these device therapies in all eligible women is important," he added.

Session discussant and scientific program committee cochair Dr Cecilia Linde (Karolinska University Hospital, Stockholm, Sweden) agreed, noting that the analysis showed that "women were withheld from important therapy."

Unstudied Populations

Varma noted that past research has suggested that ICDs may provide little or no effect in women and cause more complications, whereas CRT-Ds (in some but not all reports) have shown an enhanced effect. "And then pacemakers and CRT-Ps are relatively unstudied."

The investigators, wanting to investigate sex-specific characteristics and survival rates after implantation of a St Jude Medical remote monitoring-enabled CIED, assessed records for 269,471 patients (64.8% men; mean age 71 years).

All participants were split into one of the following four subgroups based on type of device implanted: ICDs (n=85,014) and CRT-Ds (n=61,475), which were implanted between 2008 and 2011, and PPMs (n=115,076) and CRT-Ps (n=7906), which were implanted between 2009 and 2011. Follow-ups occurred through November 2013.

Although distribution was similar between the sexes for PPMs (55% men, 45% women) and CRT-Ps (57% men, 43% women), it was significantly different for ICDs (74% men, 26% women) and CRT-Ds (72% men, 28% women).

"In other words, roughly three-quarters of the ICDs and CRT-Ds went to men," noted Varma.

Sex-Specific Survival Rates

Interestingly, the ages were similar between the sexes in each of the device groups, but the participants were older in the overall PPM (men 75.3 years, women 76.7 years) and CRT-P (75.9 and 76.5 years, respectively) groups than in the CRT-D (70.2 and 69.6 years) and especially the ICD (64.9 and 63 years) groups.

Deaths were highest in the overall CRT-D group at 19.3% per patient year, followed by the CRT-P group at 17%, the ICD group at 13.7%, and the PPM group at 11.5%.

Mortality incidence rates were significantly lower for women who received a CRT-D (5270 per 100,000 patient year) than for men (7175; relative risk [RR] 0.73, 95% CI 0.70–0.77). These rates were similar for those receiving CRT-Ps (5383 vs 7625, respectively; RR 0.71, 95% CI 0.63–0.79). There were no significant between-sex differences in those who received either an ICD or PPM.

When examining risk for all-cause mortality, which was the primary outcome, the investigators found significantly higher survival rates for the women vs men in the CRT-D (adjusted hazard ratio [HR] 0.76, 95% CI 0.72–0.79, P<0.001) and CRT-P (HR 0.69, 95% CI 0.620–0.77, P<0.001) groups. There was also slightly higher survival for women in the PPM group (HR 0.90, 95% CI 0.87–0.93).

Varma noted that strengths of this analysis includes its large size and that it "adds a large-scale PPM assessment and introduces the first large-scale CRT-P evaluation." Limitations, however, include its retrospective and observational design and that there is no nondevice comparator group, and comorbidities were not examined.

"Absolute Need" for RCTs

"Congratulations to Dr Varma for showing this big-data research with 3-year follow-up time," said Linde, calling the analysis "extremely important."

She noted that although randomized controlled trials (RCTs) should tell this same story, they do not. "Looking at pacemaker trials, they're fairly well-balanced regarding gender," but in the SCD-HeFT trial, only about one-fourth of the participants were women, said Linde, adding that similar device distribution patterns were seen in the Swedish registry study. "In real life, women receive fewer ICDs and CRT. They're receiving fewer of these life-saving devices."

Varma reported receiving consulting fees and honoraria from St Jude Medical. Linde reported also receiving consulting fees from St Jude, as well as from Cardio3, CardioMems, and Medtronic; she has also received research grants from Medtronic and the Sweden Heart and Lung Foundation.


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