When the Atrium is Not Enough, Ablation of Anteroseptal Focal Atrial Tachycardia from the Non-Coronary Aortic Cusp: A Case Report

BACKGROUND Adenosine-sensitive focal atrial tachycardias (AT) arising from the anteroseptal region are uncommon and may be difficult to ablate safely because of their proximity to the atrioventricular (AV) conduction system. Failure of conventional right or left atrial ablation should prompt consideration of alternative anatomical sites. CASE SUMMARY A 64-year-old caucasian man with no structural heart disease presented with recurrent adenosine-sensitive supraventricular tachycardia. Electrophysiological study demonstrated a long-RP focal AT with intermittent AV block and earliest activation in the anteroseptal right atrium. High-density mapping and radiofrequency (RF) applications in both atria were ineffective. Mapping of the aortic root identified the earliest atrial signal in the non-coronary cusp, 36 milliseconds before the surface P wave, with a negative unipolar electrogram. RF delivery at this site terminated the tachycardia, and additional consolidation lesions prevented recurrence. The arrhythmia was no longer inducible under isoproterenol. At 3-year follow-up, the patient remains asymptomatic without antiarrhythmic therapy. CONCLUSION The non-coronary cusp is a safe and effective ablation target for anteroseptal focal atrial tachycardia.