March 01, 2011
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MADIT-CRT: CRT-D more effective in women than men

Arshad A. J Am Coll Cardiol. 2011;57:813-820.

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Women in the randomized MADIT-CRT trial had significantly greater reductions in death or HF, HF alone and all-cause mortality with cardiac resynchronization therapy using defibrillator than men.

Researchers of the Multicenter Automatic Defibrillator Implantation Trial with Cardiac Resynchronization Therapy (MADIT-CRT) enrolled 1,820 patients (24.9% women) and analyzed sex-specific outcomes comparing the effect of cardiac resynchronization therapy with defibrillator (CRT-D) against implantable cardioverter defibrillator therapy.

They found better results with CRT-D for female patients, culminating with a 70% reduction in HF (P<.001) and a 69% reduction in death or HF (P<.001), which were significantly lower when compared with men (P<.01 for each).

Also reported was a 72% reduction of all-cause mortality in women (P<.02), as well as an 82% reduction in mortality for those with QRS of at least 150 ms and 78% reduction in those with left bundle branch block (LBBB) conduction disturbance. However, for female patients with non-LBBB, rates of death or HF (HR=1.97; 95% CI, 0.40-9.64), as well as HF alone (HR=1.95; 95% CI, 0.40-9.53), were nearly two times greater.

Significant differences in baseline characteristics between women and men, the researchers wrote, could explain part of the observed findings because a greater proportion of women had a substrate of nonischemic cardiomyopathy and an underlying LBBB pattern.

“It is possible that among patients with heart disease, the risk of HF is greater for women than for men, resulting in a greater benefit from preventive CRT-D therapy in women,” they said.

Cardiology Today’s initial coverage of MADIT-CRT can be viewed here. – by Brian Ellis

PERSPECTIVE

Dr. Arshad and her colleagues report that women in the MADIT-CRT trial obtained significantly greater reductions in death or HF, HF alone, and all-cause mortality with CRT-D therapy than men. Although these findings were associated with greater echocardiographic evidence of reverse remodeling in women compared with men, the differences were small. Furthermore, female patients were more likely to have nonischemic cardiomyopathy and LBBB and less likely to have renal dysfunction than men; these factors are known to be associated with improved outcomes. Conversely, men had more ischemic heart disease, prior revascularization and renal dysfunction. Thus, the overall findings are not surprising.

On the other hand, it is notable that women with ICDs rather than CRT-Ds had worse outcomes than men, and women had a significantly overall higher likelihood of device-related adverse events than men. Despite these findings, just as in the case of atrial fibrillation and age, male gender should not be taken to mean that men should not receive CRT-D therapy, since the subset is less likely to respond. Patients who are male, the elderly and those with atrial fibrillation simply have blunting of beneficial responses, not absent response. Why women with nonischemic cardiomyopathy seem to be more responsive to CRT than are men remains unknown.

– Andrew E. Epstein, MD

Cardiology Today Editorial Board

Disclosure: Dr. Epstein reports having served on the Data and Safety Monitoring Board for Boston Scientific, and has received speaking honoraria, fellowship support and research grants from Boston Scientific. He has also served on Data and Safety Monitoring Boards for and has received research grants, speaking honoraria and fellowship support from Medtronic/Cryocath and St. Jude Medical. Dr. Epstein also reports having received research grants and speaking honoraria from Biotronik, and has received research grants from Cameron Health and Spectranetics.

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