Abstract:
Background. Atrial flutter (AFL) often persists in the absence of appropriate therapy and
carries a high risk of thromboembolism. Flecainide, IC class antiarrhythmic drug, is effective
and safe in patients without structural heart disease but may cause proarrhythmic effects in
the presence of predisposing factors.
Objective(s). To present the clinical and paraclinical aspects of an episode of monomorphic
ventricular tachycardia (VT) in a patient with AFL and to highlight the proarrhythmic effect
of Flecainide.
Materials and methods. A 45-year-old woman known with AFL for approximately 1 year.
Chronic treatment: Flecainide 200 mg/day, Bisoprolol 5 mg/day, Apixaban 5 mg twice/day.
ECG: Typical counterclockwise AFL 4:1 with HR 75 bpm. Laboratory tests: unremarkable.
During preparing for electrical cardioversion, the patient provoked an episode of rapid
palpitations.
Results. ECG showed monomorphic ventricular tachycardia with a heart rate of 200 bpm,
superior axis, and a QRS duration of 160 ms exhibiting a left bundle branch block
morphology, with a transition zone in leads V5–V6. External electrical cardioversion at 150
J, under midazolam sedation, have restored sinusal rhythm. Echocardiography
demonstrated non-dilated cardiac chambers and preserved left ventricular ejection fraction.
Coronary angiography revealed no significant stenotic lesions. Electrophysiological study
with up to 6 atrial and 4 ventricular extrastimuli induced no arrhythmias. Cavotricuspid
isthmus ablation achieved bidirectional block.
Conclusion(s). Monomorphic ventricular tachycardia was likely triggered by the
proarrhythmic effect of Flecainide. Sinusal rhythm and hemodynamic stability were
achieved through electrical defibrillation. Cavotricuspid isthmus ablation with confirmed
bidirectional block prevented atrial flutter recurrence.
