Dengue Hemorrhagic Fever Complicated by Complete Atrioventricular Block: A Case Report.

Dengue virus (DENV) infection is a common mosquito-borne disease with a broad clinical spectrum ranging from mild febrile illness to severe manifestations such as dengue haemorrhagic fever (DHF) and dengue shock syndrome. While hematologic and vascular complications are well-documented, cardiac involvement, such as conduction abnormalities, is less well-known but potentially fatal. A 53-year-old male with a five-day history of fever, fatigue, and dizziness presented in hemodynamic instability with severe bradycardia and hypotension. An ECG showed complete heart block, requiring the urgent insertion of a temporary pacemaker. Transthoracic echocardiogram demonstrated mildly reduced left ventricular systolic function (left ventricular ejection fraction = 45%). Laboratory investigations revealed thrombocytopenia with a platelet count of 109 × 10⁹/L. The patient had no known allergic conditions. Based on the clinical presentation and high index of suspicion, a dengue test was performed, confirming the infection through positive IgM serology and reverse transcriptase-polymerase chain reaction, which identified the DENV-2 serotype. Despite supportive care, the patient did not recover a normal cardiac rhythm and ultimately required a permanent pacemaker. This case highlights the potential for complete heart block as a severe complication of DHF.