RESUMO
We performed 12-lead electrocardiographic monitoring in 97 patients during coronary angioplasty (PTCA) of a single vessel to correlate ischemic ST changes with clinical, angiographic and coronary hemodynamic variables and to determine the optimum lead or combination of leads for their detection. Ischemia (chest pain or ST change, group A) occurred in 79 patients (80%), but in only 15 of 23 patients (65%) with collaterals (p less than 0.05). Ischemia occurred more often in left anterior descending and left circumflex PTCA than right coronary PTCA, but pain was the only manifestation more often in left circumflex and right coronary PTCA. Ischemic ST change was silent in 16% and this proportion did not differ in clinical or angiographic groups except for diabetes with 3 of 5 (60%) having silent ischemia (p less than 0.05). Patients in group A (ischemia) compared to group B (no ischemia) had less severe lesions (85 +/- 9 vs 91 +/- 7%, p less than 0.01), higher transstenotic gradients (62 +/- 19 vs 53 +/- 9 mm Hg, p less than 0.05) and lower distal occluded pressures (24 +/- 11 vs 33 +/- 10 mm Hg, p less than 0.01), suggesting less collateral flow. Compared with a 12-lead electrocardiogram, the best single lead for detecting ST change during PTCA in each artery had a sensitivity of 80% and this increased to 93% using the best 2 leads. The best 3 leads (V3/III/V5 for left anterior descending and III/V2/V5 for right coronary and left circumflex) increased sensitivity to 100%.(ABSTRACT TRUNCATED AT 250 WORDS)