A rare cause of syncope in a young female

A 39 year-old female with one-week history of chills, night sweats and myalgias presented after a syncopal episode. Physical examination was unremarkable and electrocardiogram showed normal sinus rhythm with left bundle branch block. Troponin I (7.39 ng/mL), erythrocyte sedimentation rate (96 mm/h) and C-reactive protein (74.8 mg/L) were elevated. Shortly after admission, another syncopal episode occurred associated with complete atrioventricular (AV) block (Fig. 1A ) followed by ventricular escape rhythm (Fig. 1B). Transvenous temporary pacemaker was placed. Coronary arteriogram demonstrated normal coronary arteries. Left ventricular (LV) ejection fraction was 40% by echocardiogram. Cardiac positron emission tomography scan showed hypermetabolic activity throughout the entire myocardium consistent with diffuse inflammation (Fig. 1C). Right ventricular biopsy revealed severe diffuse inflammation with associated myocardial injury and scattered multinucleated giant cells (Fig. 1D). The patient developed cardiogenic shock with ventricular tachycardia despite therapy with corticosteroids and cyclosporine. For hemodynamic support, veno-arterial extracorporeal membranous oxygenation was used. Hemodynamics, ventricular tachycardia and AV-block resolved after one-week. Biventricular cardioverter–defibrillator was implanted and the patient was discharged on cyclosporine, prednisone and heart failure therapy. On clinic follow-up the patient was doing well without symptoms.

Symptoms and right ventricular biopsy were consistent with giant cell myocarditis (GCM). GCM is a rare, frequently fatal disease characterized by T-cell mediated inflammation of the myocardium. Incidence is 0.007–0.051% and affected patients are generally healthy middle-aged adults. Most common presentation consists of acute heart failure that may progress rapidly to cardiogenic shock and death. Mechanical circulatory support or heart transplantation may be life-saving []. One-fourth of patients present with ventricular arrhythmias, heart block or symptoms consistent with myocardial infarction []. The incidence of high-grade AV-block requiring a pacemaker is higher in GCM compared to lymphocytic myocarditis due to viral infection (60% versus 8.3% of patients, respectively) []. With immunosuppression, high-grade AV-block may resolve []. Histopathology is necessary for the diagnosis of GCM, which shows diffuse myocardial necrosis, inflammatory infiltrates with presence of multinucleated giant cells and absence of granulomas. Prognosis is poor without therapy with a rate of death or cardiac transplantation of approximately 90% and a median survival of 5–6 months from symptom onset []. This case highlights the rapid clinical deterioration that often occurs in GCM and the importance of early diagnosis and treatment. With the administration of immunosuppression therapy and mechanical circulatory support, when needed, the one transplant-free survival is approximately 75% [].

When evaluating patients with myocarditis, GCM should be considered when high-grade AV-block is present. Physicians should be aware of the potential for rapid deterioration and high mortality rates associated with this disease. Aggressive and early management could be lifesaving.

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