Hibernating myocardium: clinical and functional response to revascularisation

Area of Science:

• Cardiology
• Cardiac Surgery
• Nuclear Cardiology

Background:

• Severe left ventricular (LV) impairment affects cardiac function and exercise capacity.
• Myocardial hibernation, a state of impaired contractility despite preserved viability, is a potential target for revascularization.

Purpose of the Study:

• To assess the impact of coronary artery bypass grafting (CABG) on LV function, exercise capacity, and symptoms in patients with LV impairment.
• To evaluate the role of identifying myocardial hibernation in predicting outcomes after CABG.

Main Methods:

• A prospective non-randomized study of 47 patients with LV ejection fraction < 35% and three-vessel coronary artery disease.
• Patients underwent Tl-201 imaging and cine MRI for LV function assessment.
• Group 1 (n=30) received CABG; Group 2 (n=17) received medical therapy alone.

Main Results:

• CABG improved mean LV ejection fraction (LVEF) from 24.0% to 29.7% (P < 0.05) and NYHA dyspnea grade from 2.7 to 1.4.
• Medical therapy resulted in a fall in LVEF from 25.7% to 20.6% (P < 0.05) and unchanged dyspnea grade.
• Patients with myocardial hibernation showed significant improvement in LVEF (95%) and NYHA class (86%) after CABG, compared to those without hibernation.

Conclusions:

• Coronary artery bypass grafting improves global and regional LV function and symptoms in patients with severe LV impairment and myocardial hibernation.
• Medical treatment does not improve LV contractile function or symptoms in these patients.
• Both surgical and medical therapies are associated with a high mortality rate.