HISTOPATHOLOGIC CORRELATES OF UNSTABLE ISCHEMIC SYNDROMES IN PATIENTS UNDERGOING DIRECTIONAL CORONARY ATHERECTOMY - IN-VIVO EVIDENCE OF THROMBOSIS, ULCERATION, AND INFLAMMATION

Complex coronary morphologic abnormalities with thrombus and ulceration have been recognized in acute ischemic syndromes by angiography, angioscopy, and autopsy. However, in vivo histopathologic correlates of unstable ischemic syndromes have not been described. The purpose of this study was to characterize intracoronary lesion morphologic abnormalities by analyzing specimens excised by directional atherectomy in patients with different ischemic syndromes. Tissue specimens removed by directional coronary atherectomy of primary lesions in native vessels were matched blindly to the clinical status of 130 patients representing 43% of a consecutive directional coronary atherectomy population of 300 patients; 824 specimens (range per patient 1 to 30, mean 6.3) were obtained. Clinical subgroups were prospectively classified as recent myocardial infarction (less than or equal to 15 days, mean 6, range 1 to 15 days), 48 patients; prolonged rest angina, 34 patients; crescendo angina, 29 patients; and stable angina, 19 patients. Shavings were prospectively analyzed for presence of thrombus, ulceration, or chronic inflammatory cells. Thrombus was observed in 33 (69%) patients with recent myocardial infarction, 17 (50%) with test angina, 12 (41%) with crescendo angina, 7 (37%) with stable angina (p = 0.048). Plaque ulceration was identified in 12 (25%) patients with recent myocardial infarction, 4 (12%) with rest angina, 2 (7%) with crescendo angina, and 1 (5%) with stable angina (p = 0.09). Inflammatory cells were noted in the specimens of 32 (67%) patients with recent myocardial infarction, 16 (45%) with rest angina, 12 (41%) with crescendo angina, and 9 (45%) with stable angina. With increasing severity of clinical syndrome, there was a higher prevalence of thrombus and ulceration; chronic inflammatory cells, although present in all subgroups, were more prevalent in recent myocardial infarction (p = 0.028). This study represents the in vivo histologic confirmation of acute plaque alteration in unstable ischemic syndromes; presence of plaque inflammation may have therapeutic implications and warrants further study.