Key result
Slow pathway ablation does not alter the antero-septal spike-to-His interval, confirming preserved fast pathway conduction.
Why the study?
Koch triangle mapping helps define the fast pathway location, and the authors aimed to describe it using electroanatomic activation mapping alongside conventional electrophysiology studies.
Does electroanatomic activation mapping of the Koch triangle confirm preserved fast pathway conduction properties after slow pathway ablation in AVNRT patients?
Observational (n=10)
Does electroanatomic activation mapping of the Koch triangle confirm preserved fast pathway conduction properties after slow pathway ablation in AVNRT patients?
Absolute Event Rate: 80% vs 78.5%
p-value: p=0.5
Electroanatomic activation mapping of the Koch triangle confirms that fast pathway anterograde conduction properties are preserved after successful slow pathway ablation in AVNRT patients.
Stable fast pathway metrics after KT mapping; leaves open whether electroanatomic guidance improves AVNRT ablation safety.
Introduction Slow pathway ablation is currently the target for AV nodal reentrant tachycardia (AVNRT) with a high success rate of almost 100% and 0.5% to 2% risk of II- to III-degree AV block. Kock triangle (KT) mapping is helpful to define the fast pathway location, to find out its physiologic anteroseptal location. We aimed to describe the KT mapping by means of electroanatomic (EA) activation mapping of fast pathway, performed beside the conventional EP study. Methods KT was mapped as follows: atrial pacing from peri-Hisian antero-septal (AS), mid-septal (MS) and postero-septal (PS) regions, by means of 4 mm ablating catheter beside a quadripolar diagnostic catheter placed on His region. The EA local activation time (LAT) was performed by means of Ensite X system (Abbott Medical) in all patients; the window of interest was set from 10 msec after the pacing atrial spike extended beyond the ventricular EGM on the His catheter tracing. The spike-to-His deflection (S-H) interval was measured to define the fast pathway location (activation gradient). On the ablator catheter tracing the annotation was set (ROV), timed to the His deflection on His catheter tracing; the annotation was set even when no His deflection was recorded on ablator tracing as in MS and PS regions ("mirroring"). The KT was mapped before and after successful elimination of the slow pathway. Results Ten consecutive AVNRT patients were included who underwent to successful ablation with slow pathway elimination. In all cases, at baseline pre-ablation KT mapping, a progressive prolonged S-H interval was found (AS<MS As compared to pre-ablation, the post-ablation LAT mapping showed the same activation gradient in all patients (Fig 2), as follows: 1) pre-AS=78.5 msec vs post-AS=80 msec p=0.5 2) pre-MS=98 msec vs post-MS=106 msec p=0.5 3) pre-PS=124 msec vs post PS=122 msec p=0.9 (U-Mann Whithney; Shapiro Wilk = W 0.87, 0.92, 0.80 respectively) Conclusion The activation mapping of KT by LAT may help to define the AV node dual physiology beside the conventional EP mapping. It might depict a safer region for slow pathway ablation and confirms the preserved anterograde conduction properties of fast pathway after slow pathway ablation.
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Zoppo et al. (2026) conducted an observational in AV nodal reentrant tachycardia (AVNRT) (n=10). Slow pathway ablation vs. Pre-ablation baseline was evaluated on Spike-to-His deflection (S-H) interval at antero-septal region (p=0.5). Slow pathway ablation did not significantly alter the antero-septal spike-to-His interval (80 msec post-ablation vs 78.5 msec pre-ablation, p=0.5), confirming preserved fast pathway conduction.
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