Flecainide

Abstract

Atrial flutter, left bundle branch block and prolonged QRS: case report A 59-year-old man developed atrial flutter, left bundle branch block and QRS interval prolongation during treatment with flecainide for paroxysmal atrial fibrillation (AF). The man, who had been diagnosed with refractory paroxysmal AF and atrial flutter in 2004, presented in February 2019 to a hospital in USA after developing acute respiratory distress. He had undergone three electrical cardioversions in 13 years, including one year and one week before the current presentation. After the second treatment, he started receiving flecainide 100mg twice daily to maintain sinus rhythm. His only other regular medication was anticoagulant rivaroxaban. He exhibited a sudden-onset dyspnoea, palpitations and a cough with pink sputum. A wide-complex tachycardia (HR 260 beats/min) was notable on telemetry, which was consistent with atrial flutter with 1:1 conduction. Haemodynamic instability was also noted. The man therefore underwent cardioversion with a direct-current with synchronised 100-J shock. However, due to his ventricular rate, the synchronised shock immediately precipitated ventricular fibrillation secondary to the R-on-T phenomenon. A 360-J shock restored his sinus rhythm. He temporarily lost his consciousness after the first cardioversion. He was shifted to a hospital. On hospital arrival, his ECG revealed QRS prolongation and left bundle branch block. Flecainide-related atrial fibrillation was suspected. Flecainide was therefore discontinued. He had hypoxia, tachypnea and respiratory distress with bilateral rales at the lung bases. The day after hospital admission, he underwent radiofrequency catheter ablation across the cavotricuspid isthmus for the treatment of highly symptomatic atrial flutter. He tolerated the procedure without complication. His sinus rhythm was maintained. He discharged from the hospital with the instruction of outpatient cardiology follow-up. After 3 months, he underwent outpatient AF cryoablation. At 3-month follow-up, his ECG showed normal QRS duration, sinus rhythm and no left bundle branch block. Thus, it was confirmed that his atrial flutter, left bundle branch block and prolonged QRS duration was associated with flecainide.