Functional importance of coronary collateral vessels

Area of Science:

• Cardiology
• Physiology

Background:

• Coronary collateral vessels' role in mitigating exercise-induced myocardial dysfunction is debated.
• Patients with significant coronary artery stenosis often have collateral circulation.

Purpose of the Study:

• To assess the impact of coronary collateral vessels on left ventricular (LV) function during exercise in patients with severe coronary artery stenosis.
• To determine if collateral function mitigates exercise-induced ischemic dysfunction.

Main Methods:

• Radionuclide cineangiography was used to evaluate LV function during exercise in 125 patients.
• Patients had at least one major coronary artery with >=90% stenosis and no prior myocardial infarction.
• Regional and global LV function were assessed, with collateral vessel status graded.

Main Results:

• Regional LV function worsened during exercise in 33% of regions with good collaterals versus 70% without (p<0.001).
• Even with good collaterals, regions supplied by arteries with >=75% stenosis showed worsened function (71%).
• Patients with good collaterals maintained higher LV ejection fraction during exercise (46%) compared to those without (41%, p<0.005).

Conclusions:

• Good coronary collateral vessels significantly mitigate exercise-induced regional and global left ventricular dysfunction in patients with severe coronary artery stenosis.
• The protective effect of collaterals is evident even when the supplying artery is highly stenosed.
• Coronary collateral function is crucial for preserving myocardial function during ischemic stress.