Safety and Effectiveness of Medical Device Therapy

Abstract

When enough females and males are enrolled in clinical trials, much more relevant information is available on potential sex differences in device safety and effectiveness. Unfortunately, females have largely been underrepresented in clinical studies of cardiac medical device therapies for heart failure. In this chapter, sex differences in heart failure characteristics and cardiac electrophysiology and their influence on the safety, effectiveness, and application of implantable cardioverter defibrillators (ICDs), subcutaneous ICDs (S-ICDs), and cardiac resynchronization therapy (CRT) will be discussed. In this way, the research community will hopefully become more appreciative of the potential differences in device effects between females and males.

Prediction of a super‐response to cardiac resynchronization therapy as guided by left ventricular end‐systolic volume size

“…Clearly, as women tend to have relatively smaller ESV size at baseline, their benefit from CRT surpasses the gain expected in men. These advantages for women have also been reported following analysis of real‐world registries 2,10 …”

“…The most severe form refers to a left bundle branch block (LBBB), where the two walls are (from an electrical conduction point of view) completely uncoupled and the lateral wall contracts about 100 ms later than the septum. It is postulated that since females have shorter QRS duration at baseline, they may be more susceptible to develop LBBB compared with males 2 . Thus, the three STS components appear to be coupled, as women have smaller heart size, with larger delay time.…”

“…There are sex‐specific differences in cardiac electrophysiology that can potentially affect device response 2 . Females have ~5 ms shorter QRS duration than males at baseline, likely because of their smaller heart size.…”

“…There are sex-specific differences in cardiac electrophysiology that can potentially affect device response. 2 Females have 5 ms shorter QRS duration than males at baseline, likely because of their smaller heart size. With heart failure, the LV in both females and males dilates, causing dyssynchrony in septal and LV lateral wall contraction and therefore lower LVEF.…”

“…Despite application of uniform selection criteria, individual response to this type of therapy varies widely. Notably, a subgroup of super‐responders has been documented 2 . Therefore, it is of eminent importance to determine factors that can predict favorable response to this intervention and identify within the broad spectrum (which also includes negative‐responders) those patients who may benefit from CRT.…”