[Clinical features of patients with spontaneous recanalization of the infarct-related artery during evolving acute myocardial infarction].

The clinical features of 124 patients with incompletely obstructed infarct-related arteries during the early stages of myocardial infarction (Group 1) were compared with those of 212 patients having completely occluded coronary arteries (Group 2). Coronary angiography was performed within 12 hours after onset of symptoms in all cases. Patients treated with emergency coronary angioplasty were excluded from the study. Thrombolytic therapy, performed in both groups whenever intracoronary thrombi were detected, was successful in 61% of Group 2. Results were as follows: 1. In Group 1, three-vessel disease was observed more frequently than one-vessel disease (49 vs 27%, p less than 0.005). 2. The peak level of CPK was higher in Group 2 (p less than 0.001), and left ventricular ejection fraction was higher in Group 1 (66 +/- 16 vs 56 +/- 14%, p less than 0.01). 3. Either significant ST elevation or the Q wave was more commonly absent in Group 1 (31 vs 12%, p less than 0.01; 49 vs 12%, p less than 0.001). 4. Improvement of ejection fraction was observed in Group 1, but not in Group 2 even if the infarct-related artery was recanalized within six hours. 5. Extension of an infarct area was more common in Group 1 compared to Group 2 which was successfully treated with thrombolytic therapy (12 vs 3.9%, p less than 0.05). 6. The most important cause of death was extension of an infarct area in Group 1 and pump failure in Group 2, though hospital mortality rates were similar in both groups. It was concluded that patients with myocardial infarction having incompletely obstructed infarct-related coronary arteries have better left ventricular function and higher rates of non-Q myocardial infarction compared with those who had completely obstructed coronary arteries. However, extensions of infarcted areas commonly occur in these patients.