Long RP tachycardia: a diagnostic challenge. A case report.

Permanent junctional reciprocating tachycardia (PJRT), also known as Coumel tachycardia, is a rare form of supraventricular tachycardia predominant in children and classically associated with tachycardia-induced cardiomyopathy. Its occurrence in adults is uncommon, and recurrence after a previously failed conventional ablation is even less frequently reported. We report the case of a 33-year-old woman with palpitations since childhood. At 12 years of age, she underwent a conventional electrophysiological study with radiofrequency ablation. However, symptoms persisted, requiring multiple antiarrhythmic drugs and frequent emergency department visits with only partial control, prompting a redo procedure. On this occasion, three-dimensional electroanatomical mapping with the "open-window" technique was used. During the procedure, orthodromic reciprocating tachycardia (ORT) using a right posteroseptal occult accessory pathway with decremental retrograde conduction was diagnosed. Radiofrequency ablation of the accessory pathway was successful, with a favorable clinical outcome at follow-up. Coumel tachycardia is an unusual type of supraventricular tachycardia, even more so in adults. The diagnostic approach begins with the electrocardiogram and extends to invasive methods such as electroanatomical mapping, which enable precise characterization of the arrhythmic substrate.