Clinically suspected acute right ventricular fulminant dengue myocarditis masquerading with dual lethal arrhythmias: a case report.

Background: Acute right ventricular myocarditis is rare, comprising only 18% of myocarditis cases. Despite being relatively infrequent at 12.4%, dengue-induced myocarditis has a high mortality risk of 26.4%. This report presents a novel case of acute fulminant right ventricular myocarditis due to severe dengue infection, complicated by dual electrical disturbances: complete heart block and ventricular tachycardia.

Case Report: A 49-year-old Asian male patient was referred to our hospital with a temporary pacemaker due to a complete heart block. He had a history of recurrent syncope over three days and a fever five days before admission. Initial electrocardiography showed a total atrioventricular nodal block progressing to a high-degree atrioventricular block with a left bundle branch block, indicating an infra-Hisian block. Laboratory findings included thrombocytopenia, elevated troponin, high creatinine, increased liver transaminases, and a positive dengue nonstructural protein 1 test, confirming a diagnosis of dengue infection. Echocardiography showed reduced right ventricular systolic function, normal left ventricular systolic function (ejection fraction: 50%), and dyskinetic intraventricular septum. Coronary angiography revealed normal coronary anatomy. An endomyocardial biopsy was deferred due to severe thrombocytopenia. On the third day, the patient's condition worsened, developing cardiogenic shock and left ventricular systolic dysfunction (ejection fraction: 35%). He subsequently experienced a seizure and slow ventricular tachycardia originating from the right coronary cusp, followed by cardiac arrest. The patient's family claimed not to resuscitate the patient. Furthermore, the patient died shortly after.

Conclusion: This case underscores the critical need for prompt diagnosis and aggressive management of clinically suspected acute fulminant right ventricular myocarditis because complications can rapidly progress to left ventricular systolic dysfunction, leading to cardiogenic shock and sudden cardiac death.