Coronary occlusions in first non-ST segment elevation myocardial infarction

Background

Patients with ST segment elevation myocardial infarction usually have a total coronary thrombotic occlusion, and acute reperfusion reduces mortality in this setting. In contrast, patients with non-ST segment elevation myocardial infarction (NSTEMI) represent a more heterogeneous group in which a non-occlusive thrombus has been suggested as a main pathophysiologic mechanism. However, some of these patients may also present a total coronary occlusion but they are not identified as an early reperfusion target.

Methods

Our objective was to analyze the TIMI flow status in 120 consecutive patients with their first NSTEMI. The admission 12-lead ECG and coronary angiographies were reviewed and coronary occlusion was defined as TIMI flow <3. Patients with Q waves or ST segment elevation with reperfusion criteria were excluded.

Results

Mean age was 64 ± 15 years, 78 males (65%). In 77 (64%) patients the culprit lesion was identified, in 33 (27%) there were >1 possible culprit lesions, and no significant stenosis were found in 10 patients. Fifty-one patients (42%) presented TIMI <3 (30 TIMI 0, eight TIMI 1, 13 TIMI 2) in at least one major coronary artery. Collateral flow was found in 20 (17%). Thirty-two percent of patients presented one-vessel, 35% two-vessel and 22% three-vessel disease. Seventy-four patients were treated with GP IIb/IIIa antagonist and in 74 a PTCA was performed (93%). Two patients died during admission.

Among 77 patients, in which the culprit lesion was identified (44% circumflex [CX], 36% left anterior descending coronary artery [LAD] and 19% right coronary artery [RC]), coronary occlusion was present in 38 (50%) (60% CX, 29% LAD and 10% RC, P < 0.012). Patients with culprit coronary occlusions were younger (59.5 ± 13 vs 65 ± 12 years, P = 0.03), tended to have a higher incidence of smoking and had a larger myocardial necrosis (CK MB mass 108 ± 99 vs 64 ± 60, P = 0.02) than those with nonoccluded culprits.

Conclusion

The presence of a culprit coronary occlusion, in nearly one-half of the patients with a first NSTEMI, emphasizes the need to better identify, clinically and electrocardiographically, those that could benefit from early thrombolysis or primary angioplasty.