Exaggeration of nonculprit stenosis severity during acute myocardial infarction: implications for immediate multivessel revascularization

OBJECTIVES: This study was designed to assess the prevalence and clinical significance of exaggerated nonculprit lesion stenosis in the setting of acute (<12 h) myocardial infarction (AMI). BACKGROUND: Although microvascular spasm may reduce nonculprit artery flow during AMI, it is unknown whether increased tone may exaggerate nonculprit lesion severity. METHODS: In patients with additional angiography within nine months of AMI, and significant nonculprit lesions imaged in matching views, stenosis severity was compared between studies in a random blinded fashion using validated quantitative coronary angiography software. Baseline demographics, medications, hemodynamics at each study, and clinical status at follow-up (infarct/unstable angina/stable angina) were used to determine the independent influence of the infarct presentation on stenosis exaggeration. RESULTS: From 548 patients with AMI (1/99 to 6/01, 321 with multivessel disease), 112 had additional angiography; of these 48 had 59 lesions suitable for analysis. Between infarct and noninfarct angiograms there was a significant change in minimal lumen diameter (1.53 +/- 0.51 mm vs. 1.78 +/- 0.65 mm, p < 0.001) and percentage stenosis (49.3 +/- 14.5% vs. 40.4 +/- 16.6%, p < 0.0001) of the nonculprit lesion without significant change in reference segment diameter, which was not predicted by changes in medication or hemodynamics. Twenty-one percent of patients had lesions >50% at AMI that were <50% at non-AMI angiography. Infarct versus noninfarct setting was the only significant independent predictor of change in nonculprit stenosis. CONCLUSIONS: Significant exaggeration of nonculprit lesion stenosis severity occurs at infarct angiography, which may affect revascularization decision making in an appreciable number of patients.