Relation between flow grade after thrombolytic therapy and the effect of angioplasty on left ventricular function: A prospective randomized trial

Abstract

Recent intervention trials during myocardial infarction demonstrated no benefit from emergency angioplasty after thrombolytic therapy when compared with either delayed percutaneous transluminal coronary angioplasty (PTCA) or a conservative strategy. However, it is possible that subgroups of patients may benefit from early intervention with angioplasty. We performed a prospective randomized trial in patients with a patent infarct-related artery after thrombolytic therapy to determine whether initial flow grade is related to infarct-zone function and whether patients with ineffective reperfusion (>90% stenosis or Thrombolysis in Myocardial Infarction [TIMI] flow ≤2) might benefit from immediate PTCA. Thrombolytic therapy was administered to 170 patients at a mean of 2.1 ± 0.5 hours after onset of myocardial infarction. A patent infarct-related artery that was suitable for angioplasty was present in 89 patients who comprised the study group; after randomization, 47 of 50 patients with a patent infarct-related artery had successful emergency PTCA 3.8 ± 1.5 hours after onset of symptoms, and 39 were scheduled for delayed (18 to 48-hour) PTCA. Reocclusion occurred before the scheduled (delayed) procedure in eight patients (20.5%), and was symptomatic in six. Infarct-region function (by the centerline method) measured initially, before discharge, and at 4 months was similar in both groups; improvement was significant (p < 0.001) at discharge when compared with initial values with no further change at 4 months. However, patients with ineffective reperfusion had greater hypokinesia initially (p < 0.05) compared with those with effective reperfusion (≤90% stenosis plus TIMI flow 3). Moreover, independent of the timing of PTCA, improvement was greater before discharge in patients with ineffective reperfusion (p < 0.05) with a trend also evident at 4 months. Importantly, 42 of 51 patients (82%) with a residual lumen <0.4 mm after thrombolysis had some improvement in function at discharge; this compares with a previous study in which patients with a similar degree of stenosis (without PTCA) had no improvement. Moreover, reocclusion occurred before scheduled (delayed) PTCA in 37% of patients with >90% stenosis compared with only 5% in those with ≤90% stenosis (p = 0.02). Thus flow grade is an important determinant of myocardial function in patients with a patent artery after thrombolytic therapy and is predictive both of improvement in wall motion after PTCA and early reocclusion. Data from this and the recently presented Thrombolysis and Angioplasty in Myocardial Infarction (TAMI) 5 study suggest that immediate angiography during myocardial infarction can be used to select patients who may benefit from early intervention.