Coronary collateral vessels: their significance for left ventricular histologic structure

Area of Science:

• Cardiovascular Medicine
• Cardiac Pathology
• Interventional Cardiology

Background:

• The protective role of coronary collateral vessels in left ventricular myocardium under conditions of coronary artery disease remains incompletely understood.
• Coronary artery disease (CAD) can lead to myocardial damage, and the presence of collateral circulation may influence the extent of this damage.

Purpose of the Study:

• To investigate whether coronary collateral vessels offer protection to the left ventricular myocardium in patients with coronary artery disease.
• To quantify the extent of myocardial fibrosis in relation to the presence or absence of collateral supply in severe coronary stenosis.

Main Methods:

• Light microscopic morphometry was performed on myocardial tissue samples obtained via transmural biopsy during open-heart surgery from 56 patients with CAD.
• Patients were categorized based on the degree of stenosis in the left anterior descending coronary artery and the presence or absence of collateral supply determined by preoperative angiography.
• Myocardial fibrosis was quantified, with biologically significant differences defined as transmural fibrosis exceeding +/- 6.2 percent.

Main Results:

• Patients with severe left anterior descending artery stenosis (>95%) but without collateral supply (Group B) exhibited significantly higher myocardial fibrosis (68%) compared to a control group with less stenosis (Group A, 17%).
• Patients with severe stenosis (>95%) and collateral supply (Group C) showed significantly less myocardial fibrosis (29%) compared to those without collateral supply (Group B, p < 0.001).
• The fibrosis levels in Group C were not significantly different from the control Group A (p > 0.05), indicating a protective effect of collateral vessels.

Conclusions:

• Myocardium supplied by collateral vessels in cases of severe coronary stenosis demonstrates substantially less fibrosis compared to myocardium without collateral supply.
• Coronary collateral vessels play a significant protective role in mitigating myocardial damage and fibrosis in the setting of severe coronary artery disease.
• These findings underscore the importance of collateral circulation in preserving myocardial viability and function.