Background: Coronary patency has been used as a measure of thrombolysis success after acute myocardial infarction. The Thrombolysis in Myocardial Infarction (TIMI) Study Group perfusion grades have gained wide acceptance, with grades 0 (no distal flow) and 1 perfusion (minimal flow) being designated as thrombolysis failures and grades 2 (partial perfusion) and 3 (complete perfusion) as thrombolysis successes. However, the significance of the individual TIMI grades on clinical outcome has not been adequately assessed.
Methods and results: To evaluate the functional significance of TIMI perfusion grades, we compared 1-day coronary patency status with ventriculographic, enzymatic, and ECG indexes of acute myocardial infarction in 298 patients treated with anistreplase or alteplase within 4 hours of myocardial infarction symptom onset. Radionuclide ejection fraction was determined at 1 week and at 1 month. Perfusion grades for the entire study population were distributed as 12% (n = 37) grades 0/1, 13% (n = 40) grade 2, and 74% (n = 221) grade 3. Patency profile did not differ between the two thrombolytic regimens. Further coronary interventions were performed after the 1-day patency determination in 43% of patients (43%, 48%, 42%, respectively, in grades 0/1, 2, and 3 patients). The outcome of grade 2 patients did not differ from grades 0/1 patients in ejection fraction, enzyme peaks, ECG markers, or morbidity index. In contrast, grade 3 patients, compared with grades 0-2 patients, showed 1) a greater global ejection fraction at 1 week (54% versus 49%, p = 0.006) and at 1 month (54% versus 49%, p = 0.01), 2) a greater infarct zone ejection fraction at 1 week (41% versus 33%, p = 0.003) and at 1 month (42% versus 32%, p = 0.003), 3) smaller enzyme peaks, significant for lactate dehydrogenase, and shorter times to enzyme peaks, significant for all four enzymes, 4) a smaller QRS score at discharge and at 1 month, and 5) a trend toward a lower morbidity index.
Conclusions: Grade 3 flow predicts significantly better outcomes than lesser grades of flow and represents an important measure of reperfusion success.