Adenosine-induced Narrow Complex Tachycardia—An Encounter with Atrial Fibrillation: a Case Report

Adenosine is commonly utilized for treating reentrant supraventricular tachyarrhythmia (SVT) and serves as a diagnostic agent to evaluate cardiac arrhythmias of uncertain type. Even though transient AV blockage is anticipated with adenosine, in rare cases, it can cause supraventricular and ventricular tachyarrhythmias due to shortened atrial action potentials and secondary sympathetic stimulation. Only a few published case reports regarding adenosine-induced arrhythmias exist. A 52-year-old perimenopausal female presented with fever (38.1 °C) and left vulvar swelling for which IV vancomycin and ceftriaxone were given followed by abscess drainage. On the second day, the patient developed persistent tachycardia (140–160 bpm) of unclear rhythm. Adenosine was administered as a diagnostic tool to treat the underlying SVT. This resulted in rebound tachycardia of 240 bpm associated with chest pain and lightheadedness. Fortunately, tachycardia and symptoms spontaneously resolved within a few seconds, and the heart rate was back to 140 bpm. The continuous rhythm strip showed atrial fibrillation that lasted for 3–4 s, diagnosed as rebound arrhythmia due to adenosine administration. As the patient’s tachycardia did not resolve with adenosine and she had no underlying atrial flutter, it was assessed that the patient’s ongoing tachycardia was likely a sinus or atrial tachycardia. A bedside POCUS showed preserved EF% and a complete collapse of IVC/reduced right atrial pressure, indicating a case of sinus tachycardia due to dehydration. Following fluid resuscitation, the heart rate resolved to 100 bpm. The patient was discharged with advice to remain hydrated. Recognizing the potential pro-arrhythmic effects of adenosine is imperative, particularly given its common utilization in emergency settings. Prioritizing awareness of these rare side effects helps optimize patient safety during adenosine administration.