Case report of 2 sudden deaths after surgery for bone fracture: Usefulness of immunohistochemical analysis of coronary artery for identifying acute myocardial infarction

RATIONALE: Death following orthopedic surgery has become rare, but does occur. Acute myocardial infarction (AMI) can be a cause of such death, but diagnosis of AMI is often challenging, even by autopsy. PATIENT CONCERNS: We have recently experienced 2 cases of sudden death after bone fracture surgery, in which AMI and pulmonary thromboembolism were clinically suspected as causes of death. Case 1 was a 60-year-old male with a history of diabetes mellitus who died 7 days after surgery for Lisfranc dislocation fracture. Case 2 was a 75-year-old female who died several hours after surgery for proximal femur fracture. DIAGNOSES: At autopsy, slight myocardial change suggestive of AMI, severe coronary stenosis, and pulmonary congestion were noted in case 1. No signs for AMI were observed, but diffuse fat emboli were identified in the pulmonary vasculature in Case 2. Thus, postmortem pathological diagnosis was AMI in case 1 and it was suggestive of fat emboli in case 2. INTERVENTIONS: Immunohistochemical analysis of smooth muscle markers in the coronary artery was performed in both cases. OUTCOMES: The positivity ratio of h-caldesmon to α-smooth muscle actin indicative of maturity of neointimal smooth muscle cells was preserved in case 2 but diminished in case 1, where coronary occlusion may have been caused via plaque rupture. LESSONS: Immunostaining of smooth muscle markers in the coronary artery may serve as a supporting tool in establishing or disregarding AMI at autopsy.