Influence of minimal angiographic visible collateral circulation on myocardial function during PTCA

The potential protective role of angiographically visible minimal collateral circulation in diagnostic angiograms, not reaching or filling the target vessel (RENTROP class 1), on myocardial function during percutaneous transluminal coronary angioplasty (PTCA), was studied in two groups of patients undergoing elective PTCA of the left anterior descending artery (LAD). In the first study group consisting of 22 patients, influence of collateral circulation class 1 on left ventricular regional function was evaluated. In this group, 14 patients showed no angiographic collaterals and 8 patients showed collateral circulation class 1 in diagnostic angiograms. Increase of end‐diastolic and end‐systolic volume indices as well as decrease of global left ventricular function was not significantly different inpatients with and without such minimal collateral circulation. In patients without collaterals, the decrease of regional left ventricular function was significantly more pronounced in the left anterior length segment (p<0.05) and a trend was observed in the anterolateral (p = 0.059) and apical (p = 0.053) segments. In a second group, consisting of 29 patients, hemodynamic parameters were measured and, in addition to grading of collateral circulation in diagnostic angiograms, angiographically visible collateral circulation was estimated during occlusion of the LAD by injecting contrast materials into the right coronary artery. An increase of angiographically visible collaterals during the ischemic period of various degrees was documented in 26 (90%) of 29 patients. Combining patients of both study groups, increase in left ventricular end‐diastolic pressure during ischemia was significantly higher (p<0.05) in patients without collaterals on diagnostic angiography (n=34) than in patients with collateral circulation class 1 (n = 14). For all patients decrease of dP/dt max as well as decrease of dP/dt min during ischemia was statistically highly significant (p<0.001). No significant differences could be documented comparing patients without (n = 34) and with collateral circulation class 1 (n = 14). Our results indicate that, in the case of acute definitive vessel occlusion during PTCA, collateral circulation class 1 in diagnostic angiograms may not protect from extensive myocardial damage. Improvement of collateral circulation during ischemia caused by acute transient vessel occlusion is common, of rapid onset but in most cases of only minimal degree.