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Paroxysmal Atrial Fibrillation on Flecainide Therapy

Published:September 24, 2020DOI:https://doi.org/10.1016/j.ejim.2020.09.014

      Abstract

      Flecainide pill-in-the-pocket therapy is a pharmacologic treatment option for patients with infrequent episodes of symptomatic atrial fibrillation. We report a case of wide complex tachycardia due to atrial flutter with 1:1 atrioventricular conduction in a patient who took pill-in-the-pocket flecainide without concomitant atrioventricular nodalblockade.

      Keywords

      1. Case Description

      A 53-year-old female with a history of paroxysmal atrial fibrillation developed palpitations at home. She was previously managed on metoprolol succinate 25 mg daily, but ran out of the medication three days prior. A commercially available, fingertip electrocardiogram (ECG) monitor was used to detect atrial fibrillation at 160 bpm. She took 200 mg of flecainide as prescribed for pill-in-the-pocket use. However, her palpitations worsened. She called her physician who recommended that she seek urgent evaluation. On arrival, her heart rate was 202 bpm with a blood pressure of 90/63 mmHg. A 12-lead ECG was obtained (Fig. 1).
      Fig. 1
      Fig. 1ECG showing a regular wide complex tachycardia with a left bundle branch block morphology. HR 202 bpm, QRS interval 122 ms with a northwest axis. What is the diagnosis?

      2. Case Discussion

      The correct diagnosis is atrial flutter with 1:1 atrioventricular (AV) conduction. While this is an ECG diagnosis, the case description should heighten the astute clinician's suspicion for atrial flutter with rapid ventricular response.
      Flecainide is a class IC anti-arrhythmic medication often prescribed for patients with short, infrequent episodes of symptomatic atrial fibrillation. Through its effect on sodium channels, flecainide can safely and effectively convert atrial fibrillation to sinus rhythm. Rarely, flecainide organizes atrial fibrillation into a slow atrial flutter [
      • Falk RH.
      Proarrhythmia in patients treated for atrial fibrillation or flutter.
      ]. To prevent 1:1 conduction through the AV node should conversion to atrial flutter occur, patients on flecainide must take a concomitant AV nodal-blocking medication such as a beta blocker or non-dihydropyridine calcium channel blocker [
      • January CT
      • Wann LS
      • Alpert JS
      • et al.
      2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society.
      ]. Our patient ran out of metoprolol and proceeded to take flecainide without AV-nodal blocking medication, placing her at high risk of atrial flutter with 1:1 conduction.
      When evaluating an ECG with a wide complex tachycardia, clinicians must differentiate ventricular tachycardia from supraventricular tachycardia with aberrancy. On careful review of our ECG, flutter waves can be seen in a 1:1 relationship with QRS complexes. This is most evident in lead I. Vagal maneuvers or adenosine may be used to confirm atrial flutter with aberrancy in a stable patient. However, a definitive diagnosis is not always possible. In cases of hemodynamic compromise, electrical cardioversion should promptly occur regardless of the etiology of a wide complex tachycardia.

      Declaration of Competing Interest

      The authors declare they have no conflict of interest

      References

        • Falk RH.
        Proarrhythmia in patients treated for atrial fibrillation or flutter.
        Ann Intern Med. 1992; 117: 141-150
        • January CT
        • Wann LS
        • Alpert JS
        • et al.
        2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society.
        J Am Coll Cardiol. 2014; 64: e1-76