A 22-Year-Old Male With No Prior Medical History Presented to the Emergency Department with 2 Days of Intermittent Chest Discomfort
A 22-year-old male with no prior medical history presented to the Emergency Department with 2 days of intermittent chest discomfort. On arrival, his vital signs were unremarkable with a temperature of 98.3 oF, blood pressure 135/79 mmHg, pulse 91 beats/minute, respirations 12 breaths/minute, and SpO2 98% on room air. Blood pressure was equal in both upper extremities. Cardiovascular examination was within normal limits. Electrocardiogram (Figure 1) was notable for ST elevation in leads I and AVL with concomitant ST depression in leads III and AVF. Urine toxicology screen was negative. Cardiac catheterization laboratory was activated and patient was transferred for emergent coronary angiography. In the interim, initial troponin T resulted at 0.51 ng/mL (peak 0.7 ng/mL) with a CK-MB 30 ng/mL (peak 42 ng/mL). Coronary angiography demonstrated slow flow in the LAD with mild disease in the distal portion of the vessel (Figures 2a to 2d). Left ventriculography demonstrated a left ventricular ejection fraction (LVEF) of 45% and no significant aortic or mitral insufficiency. Left ventricular end-diastolic pressure was 16 mmHg. Inflammatory markers were markedly positive with an ultrasensitive CRP of 50 mg/L. ANA was negative. Cardiac MRI with delayed-enhancement imaging similarly revealed a LVEF of 48% in addition to sub-epicardial enhancement affecting the entire inferolateral and lateral walls with extension to the overlying pericardium (see Figure 3). Based upon the above findings, the patient was diagnosed with acute perimyocarditis and commenced on carvedilol, lisinopril, and low-dose ibuprofen, with instructions to restrict his exercise for 6 months. The patient has since done well from a cardiovascular perspective with normalization of his LVEF on follow up MRI and echocardiogram.
Figure 1: Presenting EKG demonstrating lateral ST elevation.
Figure 2a-2d: Coronary angiogram demonstrating the absence of any obstructive coronary artery disease.
Figure 3: Cardiac MRI short axis sequence with gadolinium. Note the presence of focal delayed enhancement in the subepicardial portions of the lateral and inferolateral walls (see arrow).
What is the proposed mechanism for myocardial ischemia in patients such as the one above whose clinical presentation very closely resembles that of an acute myocardial infarction?