Controversies in cardiac resynchronization therapy: do sex differences in response exist?

Cardiac resynchronization therapy (CRT) is well established in the treatment of patients with heart failure, but lacks data addressing sex differences in response. Women with heart failure outnumber men, but have additional comorbidities and typically are older. Women continue to be underrepresented in clinical trials, but examining their response to a therapy across multiple studies could provide significant insight into the treatment effect. The major clinical trials did have a significant percentage of female patients, but present minimal in subgroup analysis. A few small studies comparing the effect of CRT between men and women indicate a more positive effect in women. This early data suggests CRT is at least as effective in women as it is in men, and may have additional benefit in this population.