Standardised superior vena cava isolation with a balloon-in-basket pulsed-field ablation catheter: feasibility and acute safety of two procedural workflows in 53 consecutive patients

Pulsed-field ablation (PFA) is established for pulmonary vein isolation, but data on superior vena cava (SVC) isolation are limited. We assessed the feasibility and acute safety of SVC isolation with the Volt™ balloon-in-basket PFA catheter using two sequentially applied standardised workflows. Retrospective single-centre series of 53 consecutive patients undergoing atrial fibrillation ablation with adjunctive SVC isolation. Workflow 1 (n = 28) used phrenic-nerve pacing and tailored energy; Workflow 2 (n = 25) used low-energy PFA only without phrenic pacing; both shared mapping-guided sinus-node sparing and a 20-second flow-preservation manoeuvre. A pre-specified within-platform sensitivity analysis controlled for a concurrent catheter iteration (20 January 2026). Acute SVC isolation was achieved in all 53 patients (100%, 95% CI 93.3–100%). No phrenic-nerve injury and no permanent atrioventricular block occurred (0/53); one Workflow 1 patient had transient junctional rhythm that resolved spontaneously. Workflow-attributable differences were confined to SVC-specific metrics and persisted within a single catheter-platform era: Workflow 2 used low-energy applications exclusively, required more applications (median 5 vs. 4; p = 0.010), and had a longer SVC isolation time (10.7 vs. 8.5 min; p = 0.006). Shorter procedure and fluoroscopy times in Workflow 2 did not persist within a single catheter-platform era (p = 0.94, p = 0.35). Median follow-up 84 days (data censored 1 July 2026). SVC isolation with the Volt™ balloon-in-basket PFA catheter is feasible with favourable acute safety. A simplified low-energy-only protocol without phrenic-nerve pacing is a reasonable alternative to a phrenic-paced tailored-energy protocol. Durability and rhythm outcomes require dedicated follow-up study. Largest consecutive single-centre series of SVC isolation with the Volt™ balloon-in-basket catheter (n = 53), more than five-fold larger than the initial workflow report of Tilz and colleagues (n = 10). Within-platform sensitivity analysis is consistent with the interpretation that apparent gains in procedure and fluoroscopy time reflect operator learning and catheter iteration rather than the workflow change. Workflow-attributable differences are confined to SVC-specific metrics: exclusive low-energy PFA in Workflow 2, no phrenic-nerve pacing, more applications and longer SVC isolation time. A simplified low-energy-only workflow without phrenic-nerve pacing achieved 100% acute SVC isolation, with no phrenic-nerve injury and no permanent atrioventricular block, comparable to the tailored-energy workflow with phrenic-nerve pacing. The study describes a systematic 20-second flow-preservation manoeuvre — motivated by physiological considerations rather than by outcome-controlled data.