Left ventricular remodeling in myocardial hibernation

Area of Science:

• Cardiovascular Research
• Cardiac Physiology
• Myocardial Remodeling

Background:

• Left ventricular (LV) remodeling is a known consequence of extensive myocardial infarction.
• Previous studies established this link in both animal models and human subjects.
• The current study investigates if regional LV dysfunction, without significant infarction, can initiate remodeling.

Purpose of the Study:

• To determine if regional LV dysfunction with myocardial hibernation, in the absence of transmural or extensive infarction, can initiate LV remodeling.
• To explore the role of coronary stenosis in inducing these changes.
• To assess the reversibility of functional deficits and remodeling.

Main Methods:

• A severe left anterior descending coronary artery stenosis was induced in 13 pigs to reduce coronary flow by approximately 40%.
• Regional coronary flow, wall thickening, lactate production, and pH were monitored.
• LV end-diastolic volume and mass were measured at baseline, immediately after stenosis, and after 7 days.

Main Results:

• Reduced coronary flow induced acute myocardial ischemia, evidenced by decreased wall thickening, lactate production, and pH.
• Pigs exhibited significant regional LV dysfunction and reduced LV ejection fraction.
• LV end-diastolic volume and LV mass increased after 7 days of myocardial hibernation.
• Regional function recovered in pigs after restoration of coronary flow, with minimal infarction in most animals.

Conclusions:

• LV remodeling can be initiated by regional dysfunctional hibernating myocardium caused by severe coronary stenosis.
• Myocardial necrosis is not a prerequisite for LV remodeling in response to regional dysfunction.
• These findings highlight a mechanism for remodeling independent of extensive infarction.