Abstract Background Flecainide is a Class IC antiarrhythmic drug used to treat arrhythmias such as atrial fibrillation (AF), paroxysmal supraventricular tachycardia, and ventricular tachycardia (VT). Its mechanism involves blocking sodium channels, leading to QRS widening, especially at higher heart rates. This property increases the risk of pro-arrhythmic events, particularly in patients with structural heart disease or ischaemia. Case summary A 67-year-old woman receiving flecainide for AF suffered an ischaemic stroke and later developed VT resistant to amiodarone and direct current cardioversion. Her condition improved significantly after intravenous sodium bicarbonate was administered, which counteracted the effects of sodium channel blockade. Later, she was found to have hyponatremia and slightly elevated flecainide values above the upper limit. This case highlights the complexities of flecainide therapy and the importance of timely intervention in managing arrhythmias. Discussion This case underscores the arrhythmogenic potential of flecainide. The development of VT suggests that flecainide may have created a substrate for arrhythmias due to its effects on cardiac conduction. The successful use of sodium bicarbonate illustrates an effective treatment strategy for reversing flecainide-induced toxicity. Clinicians should remain vigilant and consider alternative therapies in managing patients at risk for arrhythmias while on flecainide.
Kumar et al. (Tue,) studied this question.