Cardiac-resynchronization therapy in heart failure with a narrow QRS complex

Area of Science:

• Cardiology
• Medical Devices
• Clinical Trials

Background:

• Cardiac-resynchronization therapy (CRT) is established for heart failure with wide QRS.
• Mechanical dyssynchrony exists in narrow QRS heart failure, suggesting potential CRT benefit.
• This study investigated CRT in a specific heart failure population.

Purpose of the Study:

• To evaluate the efficacy of CRT in patients with systolic heart failure and narrow QRS duration.
• To determine if CRT reduces death or heart failure hospitalizations in this cohort.
• To assess the safety and impact of CRT on mortality.

Main Methods:

• A randomized trial was conducted across 115 centers.
• Included were patients with NYHA class III/IV heart failure, LVEF ≤35%, QRS <130 ms, and LV dyssynchrony.
• Patients were randomized to CRT on or off, with primary outcome of death or hospitalization for heart failure.

Main Results:

• The study was stopped early for futility.
• No significant reduction in the primary outcome (death or heart failure hospitalization) was observed (28.7% vs. 25.2%, P=0.15).
• Mortality was significantly higher in the CRT group (11.1% vs. 6.4%, P=0.02).

Conclusions:

• CRT is not effective in reducing death or heart failure hospitalizations for patients with systolic heart failure and narrow QRS duration.
• CRT may be associated with increased mortality in this patient population.
• These findings challenge the use of CRT in narrow QRS heart failure patients with echocardiographic dyssynchrony.