Quantitation of ischemia during total coronary occlusion with computer-assisted high resolution ST-segment monitoring: effect of collateral flow.

The effect of increasing grades of collateral flow to the distal target vessel on the clinical and electrocardiographic manifestations of ischemia was evaluated in 118 patients undergoing transluminal coronary angioplasty (TCA). A qualitative scoring system for collateralization was defined as follows: 0--no visible collaterals; 1--visualization of collateral vessels only with no filling of the distal TCA vessel; 2--partial filling of the distal TCA vessel, and; 3--complete filling of the distal TCA vessel. All patients underwent computerized ST-segment monitoring using 3-channel Holter recorders. Criteria for an ischemic ST-segment response was 1.0 mm ST-segment deviation from ST baseline measured 60 msec after the J-point. Episodes of chest pain during and after the procedure were noted. Patients with collateral filling (collateral scores 2 and 3) of the distal TCA vessel had a significantly decreased incidence of angina and diagnostic ischemic ST-segment changes (42% and 15% respectively) as compared to patients without collateral filling (collateral scores 0 and 1) (83% and 74%) (p less than .001). Fifty-eight percent of patients without collateral filling had ischemic ST-segment responses on every balloon inflation as opposed to only 9% with collateral filling (p less than .0001). After TCA, the incidence of angina and ischemic ST-segment changes was similar in both groups (20% and 17% without collateral filling vs. 9% and 9%). We conclude that: 1. increasing qualitative collateralization protects against the development of myocardial ischemia during TCA, but; 2. the similar incidence of late episodes of ischemia after successful TCA suggests that collateral flow may no longer be adequate.