Global myocardial index in patients with multisite pacing

Area of Science:

• Cardiology
• Biomedical Engineering
• Medical Imaging

Background:

• Heart failure management often involves cardiac resynchronization therapy (CRT) using biventricular pacing (Bi-V).
• Evaluating the effectiveness of CRT relies on various clinical, electrocardiographic, and echocardiographic parameters.
• Global myocardial index (GMI) is a sensitive echocardiographic measure of global cardiac function.

Purpose of the Study:

• To compare changes in GMI with established parameters for evaluating ventricular resynchronization.
• To assess GMI's potential as a marker for positive clinical response to Bi-V pacing.

Main Methods:

• 35 patients with severe heart failure received Bi-V pacemakers.
• NYHA class, QRS duration (QRSd), interventricular delay (IVD), and GMI were measured pre-implantation and at 1, 7, and 30 days post-implantation.
• Measurements were taken in both paced and non-paced conditions.

Main Results:

• NYHA class improved significantly post-Bi-V pacing (p<0.01).
• GMI showed significant improvement (p<0.0001) and remained stable throughout the study.
• GMI decrease (dGMI) correlated with NYHA class improvement and IVD shortening (r=0.67, p<0.0001), but not QRSd shortening.

Conclusions:

• GMI improves with Bi-V pacing, particularly in responders, with sustained benefits.
• The reduction in GMI induced by Bi-V pacing is a reliable indicator of improved cardiac function and clinical response.