High-density mapping of upper loop macroreentry surrounding the superior vena cava: Substrate-evolved ablation...

The circuit of scar-related upper loop macroreentry atrial flutter (AFL) surrounding the superior vena cava (SVC) has been described by prior case reports. However, the correlation between the circuit and arrhythmogenic substrates and the corresponding optimized ablation strategy need to be further investigated.

We aimed to identify the electrophysiologic substrate and corresponding ablation strategies of SVC-AFL using high-resolution mapping.

From June 1, 2017, to May 1, 2023, consecutive patients with macroreentrant atrial tachycardias (ATs) from 7 institutions were retrospectively evaluated. Patients with SVC-AFL were enrolled and analyzed.

Of 1282 patients with macroreentrant ATs, 16 patients (1.2%; median age, 60.9 years; 8 male) had SVC-AFL (mean cycle length, 281.0 ± 55.1 ms), all identified during high-resolution activation mapping. All patients had prior cardiac surgery (14 [87.5%]) or catheter ablation (8 [50.0%]). A longitudinal surgical incision/scar extending from the SVC to the right atrium was observed in all patients, enabling macroreentry. SVC-AFLs with shorter circuits (<180 mm) had more slow conduction areas than those with longer circuits (>180 mm; 3.0 [2.0-4.0] vs 1.0 [1.0-1.5]; P = .023]. All ATs were terminated by ablating the channel between the surgical incision/scar and anatomic barriers. Cavotricuspid isthmus block was achieved in all patients. During a 21-month follow-up, all patients were free of atrial arrhythmias except for 4 patients experiencing short-lived paroxysmal ATs that did not require further ablation.

A surgical incision/scar extending from the SVC to right atrium promotes the development of SVC-AFL. Substrate-based linear lesions along with prophylactic cavotricuspid isthmus ablation afford favorable clinical outcomes.