The resynchronization therapy in narrow QRS study (RethinQ study): methods and protocol design.

Area of Science:

• Cardiology
• Medical Devices
• Heart Failure Management

Background:

• Cardiac resynchronization therapy (CRT) is effective for heart failure (HF) patients with wide QRS duration.
• Current guidelines recommend CRT for specific HF patient criteria (EF <35%, NYHA Class III-IV, QRSd ≥120 ms).
• Electrical dyssynchrony (QRS duration) is an unreliable predictor of CRT response; mechanical dyssynchrony may be more accurate, especially in narrow QRS patients.

Purpose of the Study:

• To evaluate the effectiveness of CRT in heart failure patients with narrow QRS duration and mechanical dyssynchrony.
• To assess if echocardiographic criteria for mechanical dyssynchrony can identify patients who will benefit from CRT.
• To investigate CRT eligibility based on mechanical dyssynchrony in narrow QRS heart failure patients.

Main Methods:

• Prospective, multi-center, randomized, double-blind controlled clinical study.
• Inclusion criteria: approved ICD indication, advanced HF (NYHA Class III), narrow QRS duration (<130 ms), and evidence of mechanical dyssynchrony (MD) via echocardiography.
• Evaluation of CRT effectiveness in this specific patient subgroup.

Main Results:

• The study hypothesizes that patients with narrow QRS (<130 ms), advanced HF, and MD will benefit from CRT.
• Mechanical dyssynchrony, assessed by echocardiography, is hypothesized to be a key predictor of CRT response in narrow QRS patients.
• Further results pending completion of the RethinQ study.

Conclusions:

• Patients with narrow QRS duration, advanced heart failure, and mechanical dyssynchrony may benefit from CRT.
• Echocardiographic assessment of mechanical dyssynchrony could refine patient selection for CRT.
• The RethinQ study aims to provide evidence for using mechanical dyssynchrony as an eligibility criterion for CRT in narrow QRS heart failure patients.