Key result
Beta-blocker discontinuation with flecainide triggers wide complex tachycardia via use-dependent conduction slowing.
Case Report (n=1)
May warrant caution with beta-blocker discontinuation in flecainide-treated AF; hypothesis-generating and requires prospective validation.
ECG CHALLENGEA 72-year-old woman with paroxysmal atrial fibrillation on oral metoprolol 5 mg twice a day, flecainide 150 mg twice a day for rhythm control, and acenocoumarol 2 mg daily presented with vomiting, presyncope, and fatigue of 3 days duration.Examination revealed a heart rate of 110 bpm, blood pressure of 106/78 mm Hg, and systemic oxygen saturation of 98% at room air.The serum potassium was 3.76 mEq/L, serum magnesium was 1.8 mg/L, serum sodium was 124 mEq/L, and serum creatinine was 1.1 mg/dL.ECG at presentation is shown in Figure 1.What is the rhythm and how should it be treated?Please turn the page to read the diagnosis.
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Banavalikar et al. (2018) conducted a case report in Paroxysmal atrial fibrillation (n=1). Flecainide without beta-blocker was evaluated on Wide complex tachycardia (atrial flutter with 1:1 conduction). Discontinuation of beta-blocker therapy in a patient taking flecainide for atrial fibrillation led to an elevated heart rate and subsequent dangerous wide complex tachycardia due to flecainide's use-dependent properties.
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