Congenital Long QT Syndrome Presenting as Ventricular Fibrillation and Syncope in a Drug-Naive Elderly Female Patient Without Prior Cardiac History.

Long QT syndrome (LQTS) is a rare cardiac electrophysiological disorder that predisposes individuals to life-threatening arrhythmias such as torsades de pointes and ventricular fibrillation (VF). It may be congenital or acquired, with many cases triggered by specific medications or electrolyte disturbances. However, presentations in elderly individuals without prior cardiac history or drug exposure are exceedingly rare. This case report highlights a unique case of congenital LQTS presenting with VF and cardiac arrest in a 66-year-old woman. She presented with recurrent dizzy spells accompanied by palpitation, cold sweating, abdominal discomfort, nausea, and vomiting. While under observation in the emergency department, she experienced a sudden loss of consciousness with no palpable carotid pulse. Cardiac monitoring revealed VF, and return of spontaneous circulation was achieved after one minute of cardiopulmonary resuscitation. Electrocardiograms revealed a prolonged QTc interval of 600 ms (calculated by Fridericia's formula) and sinus bradycardia of 49 beats/minute initially before the cardiac arrest. Investigations, including cardiac enzymes, CT scan of the head, coronary angiography, echocardiography, Holter monitoring, and cardiac MRI, were unremarkable. There was no history of QT-prolonging drug use, electrolyte imbalance, or structural heart disease. Given the high suspicion of congenital LQTS, the patient underwent implantable cardioverter-defibrillator (ICD) placement and was referred for genetic testing. Her first-degree relatives were advised to undergo cardiac screening. This case underlines the importance of considering congenital LQTS in elderly patients presenting with unexplained syncope or VF, especially in the absence of common risk factors. Early recognition and ICD implantation can be life-saving. Genetic testing and family screening remain key components of management in such cases.