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Functional importance of coronary collateral vessels
Insights
Good coronary collateral vessels help preserve heart function during exercise, reducing exercise-induced ischemic dysfunction in patients with significant coronary artery stenosis.
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.
Abstract:
Angiographically demonstrable coronary collateral vessels are believed to preserve myocardial function at rest, but disagreement exists regarding the importance of collaterals in mitigating exercise-induced ischemic dysfunction. Therefore, we used radionuclide cineangiography during exercise to assess the left ventricular (LV) functional effects of collateral vessels in 125 patients with at least 1 major coronary artery that had greater than or equal to 90% diameter stenosis but without prior myocardial infarction. Regional LV function, graded on a 4-point scale, worsened during exercise by at least 1 grade in 14 of 43 regions (33%) with good collaterals, and in 70 of 98 without good collaterals (p less than 0.001). Of the 43 good collaterals, 14 were supplied by arteries with greater than or equal to 75% stenoses; 10 of 14 regions (71%) thus supplied worsened by at least 1 grade (p less than 0.01). The ischemia-mitigating effect of coronary collateral vessels also affected the magnitude of exercise-induced global dysfunction. Of 43 patients with only one greater than or equal to 90% stenotic artery, 18 had good collaterals; in these patients, average LV ejection fraction (EF) at rest was 51 +/- 8%; LVEF during exercise was 46 +/- 7%. In the 25 patients without good collaterals, LVEF at rest was 52 +/- 7%, and LVEF during exercise was 41 +/- 9% (p less than 0.005 vs good collaterals).(ABSTRACT TRUNCATED AT 250 WORDS)