Abstract 3725: Myocardial Microvascular Obstruction in Sudden Death from Acute Myocardial Infarction Occurs more often in Coronary Plaque Erosion than in Plaque Rupture
Epicardial coronary artery thrombosis is associated with myocardial microvascular obstruction (MVO) and microemboli. Clinical consequences include acute myocardial infarction and sudden cardiac death from myocardial MVO and myocyte necrosis. We thus characterized myocardial histopathology and morphometry and related these findings to epicardial coronary artery plaque in patients dying from coronary artery occlusion. Hearts from patients with proven sudden coronary death from acute coronary artery occlusion underwent histopathologic characterization for MVO, cardiac microemboli, and epicardial coronary artery plaque. Immunohistochemistry was performed on microvascular thrombus to evaluate for platelet and fibrin content. Forty four cases were studied (mean age at death 51 ± 15 yrs). All emboli and MVO thrombus stained for both fibrin and platelets, and occurred in 54% of all patients, mean 4.5 microemboli/heart. Of all occluded microvessels, 89% were less than 120 um diameter (39% were < 30 um dia), and only 4% were greater than 200 um diameter. Microvascular obstruction and emboli occurred more often in epicardial plaque erosion (74% vs 40% of cases with MVO), and was most common in the LAD territory. Histopathologic epicardial coronary stenosis severity was (mean) 74% in those with emboli and 75% in those without (p=ns). Microemboli and microvascular obstruction are very common in patients dying of acute coronary artery thrombosis. Plaque erosion may be most likely to cause such emboli, with accumulation in sub-200 micron vessels. These emboli and microvessel obstruction have a prominent clinical role due to associated myonecrosis. Interventional strategies for eliminating MVO may be useful to limit myocardial damage and prevent long term sequelae.