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.