Significance of residual coronary artery stenosis after reperfusion therapy in acute myocardial infarction

We evaluated the efficacy of reperfusion therapy in acute myocardial infarction in terms of postinfarction angina (PIA), reinfarction and coronary reocclusion. In 99 hospitalized patients with acute myocardial infarction within 6 hours after the onset of symptoms, 67 were treated using intracoronary thrombolysis (ICT) alone (Group T) and the remaining 32 using ICT followed by percutaneous transluminal coronary angioplasty (PTCA) (Group T + A). PTCA was performed for the arteries with high grade residual stenosis (TIMI grade 0, 1, 2) after ICT. Recatheterization was performed 28 +/- 12 days after hospitalization in 93% (62/67) of Group T and in all of Group T + A. There were no significant differences in age, sex, time interval from the onset to reperfusion, the extents of coronary artery disease and the Cohn grade of collaterals. However, anteroseptal infarction was more frequent in Group T than in Group T + A (p less than 0.05). Residual stenosis (diameter) at the end of intervention was 81 +/- 14% in Group T, and 48 +/- 15% in Group T + A, (p less than 0.01). Residual stenosis at recatheterization was 70 +/- 23% in Group T, and 55 +/- 22% in Group T + A (p less than NS). The incidence of PIA did not differ between the two groups (20.1% vs 6.2%). However, the incidence was higher in patients with residual stenosis of 70% or more than in those with residual stenosis of less than 70% (23.8% vs 2.9%, p less than 0.05). The incidence of reinfarction (re-elevation of CPK) did not differ between the two groups (7.4% in Group T, 6.2% in Group T + A); and neither did the incidence of coronary reocclusion at the time of recatheterization (14.5% vs 3.1%). We concluded that higher degree of residual stenosis at the end of intervention has a greater risk of PIA and reocclusion. Although differences were not statistically significant, the patients treated with ICT followed by PTCA seemed to have lower incidence of PIA and reocclusion compared with those treated with ICT alone, thus having better hospital prognosis.