Background: Although proposed to facilitate pulmonary vein isolation (PVI), high-power ablation may favor extracardiac damage. Negative component abolition of the unipolar signal reflects lesion transmurality. The present study sought to evaluate the safety and efficacy of high-power ablation using unipolar signal modification as a local end point. Methods High power and standard power were compared in 4 swine and 100 consecutive patients referred for PVI. The first 50 patients were included in the control group (25–30 W) and the last 50 patients in the study group (40–50 W). Atrial radiofrequency applications were stopped 2 s (study group and swine) or 5 s (control group) after unipolar signal modification. Ventricular radiofrequency applications of 500 J (25 W·20 s versus 50 W·10 s) were performed at the swine epicardium. Results: Swine gross necropsy did not show any extracardiac damage related to atrial lesions. At equal energy of 500 J, 50 W lesions were deeper (3±0.9 versus 2.6±1.1 mm; P =0.03) and wider (6.2±2 versus 5±2.3 mm; P =0.006) than 25 W lesions. No complications occurred during the clinical study, whatever the power output used for PVI. For a similar sinus rhythm maintenance at 12 months (90% versus 88%; P =0.75), the study group displayed higher first-pass PVI (92% versus 73%; P <0.001), lower acute pulmonary vein reconnection (2% versus 17%; P <0.001), reduced procedure time (73.1±18.2 versus 107.4±21.2 min; P <0.001), and ablation time (13±2.9 versus 30.3±8.8 min; P <0.001). Conclusions: High-power PVI guided by unipolar signal modification safely decreases procedural burden while ensuring robust 12-month outcomes.

Our findings suggest a potential benefit of real-time CF sensing technology, in reducing AF recurrence during the first year after PVI.

BACKGROUND: Fifty-watt radiofrequency applications have proven to be safe and efficient for pulmonary vein isolation (PVI). However, as PV reconnection still occurs and ablation catheter instability significantly contributes to suboptimal lesion formation, a new ablation catheter capable of delivering 90 W for 4 seconds only has been developed with the aim of improving PVI outcomes. In this setting, we sought to determine whether 90 W applications create transmural lesions without collateral damage experimentally and whether they can safely improve PVI procedures clinically compared with 50 W settings. METHODS: Experimentally, individual lesions were created in vivo in the right atrium of 6 swine with 90 W-4 seconds applications using the SmartTouch-SF catheter in a power-controlled mode (3 animals) or the QDOT-MICRO catheter in a temperature-controlled mode (3 animals). Clinically, PVI was performed in a homogenous population of 150 consecutive paroxysmal atrial fibrillation patients using CARTO and the QDOT-MICRO catheter in a temperature-controlled mode (75 patients 50 W-ablation index-guided and 75 patients 90 W-4 seconds). RESULTS: Mostly, (94.9%) experimental lesions were transmural in the thin-walled right atrium of swine. However, collateral damage was observed with both catheters in 17.9% of lesions. Clinically, 90 W procedures had a lower first-pass PVI rate (49% versus 81%, P <10 −4 ) and a higher acute PV reconnection rate (21% versus 5%, P =0.004) than 50 W procedures, whereas total procedural duration (62 versus 66 minutes, P =0.09), 1-year sinus rhythm maintenance (88% versus 90%, P =0.6) and safety (1 tamponade per group) were similar in both groups. CONCLUSIONS: Experimentally, using the QDOT-MICRO catheter, 90 W-4 seconds lesions are mostly transmural in the thin-walled right atrium of swine (median depth 1.87 mm) with a moderate lesion diameter of 6.62 mm but retain the potential for collateral damage. Clinically, 90 W-4 seconds applications are associated with a lower first-pass PVI rate and a higher acute PV reconnection rate than 50 W applications but similar safety outcomes and effectiveness at 1 year.

Long-term endocardial biventricular stimulation via a transseptal approach was safe and effective in this small population. This approach needs to be further compared with conventional epicardial pacing via the coronary sinus.

P ulmonary vein isolation (PVI) is the cornerstone for catheter ablation procedures in patients with paroxysmal atrial fibrillation (AF).1 However, there is current concern about the durability of PVI because the PV reconnection rate has been recognized as substantial and clearly associated with the recurrence of paroxysmal AF episodes. 2 Editorial see p 1050 Clinical Perspective on p 1102PV reconnection may be related to the inability to create transmural and irreversible lesions around PV ostia. 3,4 In this regard, it has been demonstrated in a porcine model that complete elimination of the negative component of the unipolar atrial electrogram (EGM), while applying radiofrequency (RF) energy, was always associated with transmural lesions, whereas the persistence of such a negative component was constantly observed in case of nontransmural lesions. 5 In clinical practice, unipolar signal modification could be a suitable electrophysiological criterion that indicates when to halt each RF energy application while performing point-bypoint PVI (because a possible transmural lesion has been created) and when to continue its application (because the lesion deployed is presumed as not transmural).Therefore, we performed a prospective study to determine whether the unipolar signal modification may be useful or not as an end point for point-by-point RF application and find out whether it could improve the clinical results of paroxysmal AF ablations in humans by allowing more durable PVI achievement. We compared the results of the present study with those of a historical group of patients with paroxysmal AF who have undergone PVI following the standard ablative approach of our institution.© 2013 American Heart Association, Inc. Circ Arrhythm Electrophysiol Original ArticleBackground-In patients treated for paroxysmal atrial fibrillation, the pulmonary vein (PV) reconnection rate is substantial and may be related to the lack of transmurality achievement while performing PV isolation (PVI). It has been experimentally demonstrated that positive unipolar atrial electrogram completion, when applying radiofrequency energy, was associated with transmural lesions. In this regard, we seek to determine whether the unipolar signal modification may be an appropriate end point for point-by-point radiofrequency application and find out whether it could improve the paroxysmal atrial fibrillation ablation results in humans. Methods and Results-Fifty consecutive patients (61±8 years old, 41 men) with paroxysmal atrial fibrillation underwent PVI using Carto and Lasso. Each radiofrequency application lasted until development of a completely positive unipolar electrogram. Fifty patients (63±9 years old, 40 men), who previously underwent PVI following the standard approach of our institution, corresponded to the control group. All PVs were isolated in all patients of both groups. However, the procedural and ablation times were significantly lower in the unipolar group compared with those of the control group, whereas the PV reconnection rate...