Effect of Coronary Collateral Circulation on Exercise Stress Test

In this study, patients who have recovery-only ST segment depression in exercise stress test were chosen. It is proposed that coronary collateral circulation could improve with stress-increased coronary perfusion, and accordingly, patients with recovery-only ST segment depression were evaluated by coronary angiography for grading the coronary collateral circulation. Twenty-one men and five women were assigned to the study group. Sixteen men and two women who had exercise-induced ST segment depression were assigned to the control group. Age and gender of both groups were not statistically different (p>0.05). The reason for terminating the exercise stress test was chest pain in two of 26 patients in the study group versus 15 of 18 in the control group (p<0.001). In both groups coronary collateral frequency and grade were directly correlated with the severity of the coronary artery disease (p<0.001 in the study group, and p<0.05 in the control group). When both groups were compared for the frequency of significant coronary collateral circulation, 14 of 26 patients in the study group versus 4 of 18 patients in the control group had significant coronary collateral circulation (p=0.035). The authors conclude that recovery-only ST segment depression correlates well with the frequency of significant coronary collateral circulation, and coronary collaterals may prevent myocardial ischemia during exercise.