Landmark clinical trails such as MADIT and MADIT II have shown that ICDs reduce mortality by preventing SCA. However, many of these patients still go on to die of heart failure. In COMPANION and CONTAK CD, cardiac resynchronization therapy was found to improve outcomes for NYHA class III and IV heart failure patients. MADIT-CRT was undertaken to determine if asymptomatic or minimally symptomatic heart failure patients benefit from early intervention with cardiac resynchronization therapy.

The MADIT-CRT trial found a 34% reduction in the risk of death or heart failure event among patients in the CRT-D group as compared with those in the ICD group. Additional hypothesis generating analyses revealed a reduction in VT/VF episodes, reduced LV volumes, and improvement in EF for the CRT-D group as well. Examining the data by different subgroups revealed that women obtained better outcomes than men and patients with left bundle branch block performed better than those without left bundle branch block.

In trying to understand the differences between men and women enrolled in the trial, a large disparity in the prevalence of left bundle branch block was discovered. Women were far more likely than men to have left bundle branch block. Looking at the LBBB population alone, there was a 57% reduction in the primary endpoint, while non-LBBB patients saw no improvement in outcomes. These findings prompted Boston Scientific’s new CRT-D indication for high risk^¹, NYHA Class I and II patients with LBBB.

^{1 High-risk is defined as QRS width ≥ 130 ms, LVEF ≤ 30%, and LBBB}

Previous clinical trials have shown that individuals who experience a heart failure hospitalization have worse outcomes than individuals with the same eligibility criteria without a heart failure event. More specifically, the SOLVD trial showed that prevention of heart failure events in the short-term, leads to reduced mortality in the long-term. In MADIT-CRT, there was a reduction in heart failure events for asymptomatic and minimally symptomatic patients over an average follow-up period of 2.4 years.

• Will there be a CMS national coverage decision?
• Is this indication exclusive to Boston Scientific?
• When it comes to device replacement, what do I do with patients that already have a CRT-D but do not have LBBB?
• What is your recommended diagnostic protocol for potential MADIT-CRT patients?
• Can you elaborate on the findings of LV lead location and response?
• Was there any benefit in women without LBBB?
• Why were patients with a QRS duration between 120 and 130 not included?
• Was RV pacing avoided in the ICD group?
• Can you elaborate on the cost-benefit of a CRT-D device?
• What happened to the RBBB patients and what was their outcome?