Syncope and QT prolongation associated with the use of herbal product and m-RNA vaccination in a young woman

Abstract

Herein, we report a case of a 31-year-old woman with syncope due to QT prolongation 36 h after the second dose of Pfizer-BioNTech vaccination. During her comprehensive history taking, she admitted the use of herbal preparation. Her initial electrocardiogram showed a QTc interval of 690 ms, and she was interned to the intensive care unit (ICU). Her biochemical findings revealed no evidence of electrolyte abnormalities, and oral propranolol was started. During ICU monitorization, she developed polymorphic ventricular tachycardia, which subsequently degenerated into ventricular fibrillation. Genetic investigation identified KCNQ1 mutation, and ICD implantation was performed. The patient was discharged with mexiletine and propranolol treatment, and the outpatient clinic follow-up was recommended.