Sarwar Shihab, Oyewunmi Oyebimbola, Bhola Karundat, Heydari Bobak
Division of Cardiology, University of Ottawa Heart Institute, University of Ottawa, Ottawa, CAN.
Department of Medicine, Cumming School of Medicine, University of Calgary, Calgary, CAN.
Cureus. 2023 Jul 26;15(7):e42473. doi: 10.7759/cureus.42473. eCollection 2023 Jul.
Myasthenia gravis (MG) complicated by myocarditis is a rare autoimmune manifestation. We present a patient who initially presented with a suspected ST-segment elevation myocardial infarction (STEMI) with angiographically normal coronary arteries. A chest CT scan revealed a large homogenous soft-tissue density anterior mediastinal mass suspicious of thymoma. Neurological deterioration in the hospital suggested a diagnosis of MG with subsequent electromyography and nerve conduction studies (EMG/NCS) and repetitive nerve stimulation (RNS) confirmation. A cardiac magnetic resonance imaging study (CMR) demonstrated diffuse myocardial edema and severe left ventricular (LV) dysfunction and sub-epicardial late gadolinium enhancement (LGE) involving all basal and mid-LV segments in addition to apical inferior and lateral segments. A diagnosis of thymoma-associated MG with myocarditis was made and the patient was successfully treated with immunosuppression. This case highlights the association of myocarditis with MG as a potential complication that should be considered in patients with cardiac symptoms, ECG changes, or biomarker elevation.
重症肌无力（MG）合并心肌炎是一种罕见的自身免疫表现。我们报告一名患者，最初表现为疑似ST段抬高型心肌梗死（STEMI），冠状动脉造影正常。胸部CT扫描显示前纵隔有一个大的均匀软组织密度肿块，怀疑为胸腺瘤。患者在医院出现神经功能恶化，提示诊断为MG，随后经肌电图和神经传导研究（EMG/NCS）以及重复神经刺激（RNS）确诊。心脏磁共振成像研究（CMR）显示弥漫性心肌水肿、严重左心室（LV）功能障碍以及心内膜下晚期钆增强（LGE），累及所有左心室基底段和中段，以及心尖下壁和侧壁段。诊断为胸腺瘤相关MG合并心肌炎，患者经免疫抑制治疗成功。该病例强调了心肌炎与MG的关联，这是一种在有心脏症状、心电图改变或生物标志物升高的患者中应考虑的潜在并发症。
