PM1023: Myocardial Infarction and Cerebrovascular Accident in an Adolescent Patient with Multisystem Inflammatory Syndrome: A Case Report

Introduction: Multisystem inflammatory syndrome in children (MIS-C) presents 4-6 weeks after COVID-19 infection. Cardiac findings include left ventricular dysfunction, coronary dilation, elevated cardiac markers, and conduction abnormalities. Another important feature of MIS-C is hypercoagulable state, which may increase the risk of life-threatening complications. Myocardial infarction has not previously been reported, though patients are typically treated with aspirin for coronary prophylaxis to prevent thrombosis. We describe a patient with MIS-C without coronary dilation who developed a myocardial infarction as well as an acute ischemic stroke in the setting of left ventricular thrombus.

Case Description: A 14-year-old male with no significant past medical history and unvaccinated against SARS-CoV-2 presented with motor aphasia, right-sided facial droop, and right arm weakness following one week of progressive fevers, headaches, and conjunctivitis. Labs were remarkable for elevated inflammatory and cardiac markers, and positive SARS-CoV-2 anti-nucleocapsid antibodies, consistent with MIS-C from prior asymptomatic and undiagnosed COVID-19 infection. Mother had tested positive for COVID-19 seven weeks prior. Head CT and MRI confirmed left frontal lobe stroke. Echocardiogram demonstrated decreased left ventricular systolic function with an ejection fraction of 47% and an echogenic mass in the apex of the left ventricle concerning for thrombus, but no coronary dilation. ECG demonstrated repolarization abnormalities, but no ST segment changes. He was diagnosed with myocarditis secondary to MIS-C.

Treatment included IVIG, high dose steroids transitioned to an oral taper, and anakinra. Lovenox and aspirin were used for anticoagulation and coronary artery protection. By hospital day 3, the left ventricular systolic function had normalized, and the thrombus was no longer visualized. Laboratory studies improved over the course of his hospital stay. He was discharged to a rehabilitation facility on hospital day 10.

At follow up cardiology clinic visits in 2 weeks and 3 months post-discharge, his left ventricular systolic function and coronary dimensions remained normal. A cardiac MRI was performed 7 months post-discharge, which revealed a focal subendocardial enhancement with mid wall extension in the inferior wall, consistent with a prior myocardial infarction. There was no evidence of active myocarditis.

Discussion: Due to the frequent finding of coronary dilation, patients with MIS-C are typically treated with prophylactic aspirin for coronary protection. However this patient had no evidence of coronary dilation on echocardiogram. We suspect that the myocardial infarction was sustained during the acute period of MIS-C and was likely embolic from left ventricular thrombus. Although hypercoagulability is a known effect of MIS-C, reports of thromboembolic complications are rare in literature with only a handful of reported cases of ischemic stroke and no prior reports of myocardial infarction.

Conclusion: Hypercoagulable state due to MIS-C may lead to thromboembolic complications including ischemic stroke and myocardial infarction, which may occur in the absence of coronary dilation.