Pacing thresholds correlate with CF in human not previously ablated LA. Since the combination of a normal bipolar voltage and a unipolar pacing threshold <2.85 mA provide reasonable parameters of validity, pacing threshold could be of interest as a surrogate for CF in LA.
P&M is a simple maneuver to identify the gaps in ablation lines around the PV. It remains efficacious in redo procedures despite the difficulties in localizing the ablation lines performed in the first procedure. The P&M maneuver reduced the radiofrequency time required to isolate the PV without compromising the efficacy.
Purpose An important attenuation of the atrial signal recorded with mini-electrodes (ME) embedded in an 8-mm tip was associated with a transmural radiofrequency lesion. Our aim was to assess if parameters obtained from ME or conventional bipoles before applications predict successful atrial lesions. Methods We prospectively included 33 consecutive patients undergoing cavotricuspid isthmus (CTI) ablation. Electrogram voltages and pacing thresholds were measured with ME and conventional bipoles before and after radiofrequency (RF) applications. The time before the loss of capture during applications was recorded. Lesions were considered successful, in accordance with preclinical data, if ME voltage decreased > 54%. Results Of 207 applications, 107 could be analyzed. During applications, voltages decreased more in the ME than in the conventional bipoles (66.8 ± 26.1% vs 37.5 ± 42.5%, P = 0.001). Likewise, pacing threshold increased significantly more using the ME (86.3 ± 22.9% ME, 52.6 ± 35.6% conventional, P = 0.001). ME pre-ablation voltages were significantly higher and pacing thresholds significantly lower in successful lesions (voltage 0.88 ± 0.71 vs 0.26 ± 0.18 mV, P = 0.0001; threshold 1.6 ± 1.7 vs 2.8 ± 3.0, P = 0.04). Neither of these parameters with conventional bipoles nor time to loss of capture showed differences. A ME voltage > 0.33 mV and a pacing threshold < 1.5 mA predicted a successful lesion with 0.78 and 0.6 sensitivity and 0.78 and 0.59 specificity. Conclusions Certain pre-ablation parameters derived from ME such as electrogram voltage and pacing threshold differ from those obtained by a conventional configuration and can predict a successful atrial lesion.
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