Introduction Our pilot study aimed to evaluate the role of local impedance drop in lesion formation during pulmonary vein isolation with a novel contact force sensing ablation catheter that records local impedance as well and to find a local impedance cut-off value that predicts successful lesion formation. Materials and methods After completing point-by-point radiofrequency pulmonary vein isolation, the success of the applications was evaluated by pacing along the ablation line at 10 mA, 2 ms pulse width. Lesions were considered successful if loss of local capture was achieved. Results Out of 645 applications, 561 were successful and 84 were unsuccessful. Compared to the unsuccessful ablation points, the successful applications were shorter (p = 0.0429) and had a larger local impedance drop (p<0.0001). There was no difference between successful and unsuccessful applications in terms of mean contact force (p = 0.8571), force-time integral (p = 0.0699) and contact force range (p = 0.0519). The optimal cut-point for the local impedance drop indicating successful lesion formation was 21.80 Ohms on the anterior wall [AUC = 0.80 (0.75–0.86), p<0.0001], and 18.30 Ohms on the posterior wall [AUC = 0.77 (0.72–0.83), p<0.0001]. A local impedance drop larger than 21.80 Ohms on the anterior wall and 18.30 Ohms on the posterior wall was associated with an increased probability of effective lesion creation [OR = 11.21, 95%CI 4.22–29.81, p<0.0001; and OR = 7.91, 95%CI 3.77–16.57, p<0.0001, respectively]. Conclusion The measurement of the local impedance may predict optimal lesion formation. A local impedance drop > 21.80 Ohms on the anterior wall and > 18.30 Ohms on the posterior wall significantly increases the probability of creating a successful lesion.

IntroductionHigh-power short-duration (HPSD) radiofrequency ablation has been proposed to produce rapid and effective lesions for pulmonary vein isolation (PVI). We aimed to evaluate the procedural characteristics and the first-pass isolation (FPI) rate of HPSD and very high-power short-duration (vHPSD) ablation compared to the low-power long-duration (LPLD) ablation technique.MethodsOne hundred fifty-six patients with atrial fibrillation (AF) were enrolled and assigned to LPLD, HPSD, or vHPSD PVI. The energy setting was 30, 50, and 90 W in the LPLD, HPSD, and vHPSD groups, respectively. In the vHPSD group, 90 W/4 s energy delivery was used in the QMODE+ setting. In the other groups, ablation index-guided applications were delivered with 30 W (LPLD) or 50 W (HPSD).ResultsBilateral PVI was achieved in all cases. Compared to the LPLD group, the HPSD and vHPSD groups had shorter procedure time [85 (75–101) min, 79 (65–91) min, and 70 (53–83) min], left atrial dwelling time [61 (55–70) min, 53 (41–56) min, and 45 (34–52) min], total RF time [1,567 (1,366–1,761) s, 1,398 (1,021–1,711) s, and 336 (247–386) s], but higher bilateral FPI rate (57, 78, and 80%) (all p-values &lt; 0.01). The use of HPSD (OR = 2.72, 95% CI 1.15–6.44, p = 0.023) and vHPSD (OR = 2.90, 95% CI 1.24–6.44, p = 0.014) ablation techniques were associated with a higher probability of bilateral FPI. The 9-month AF-recurrence rate was lower in case of HPSD and vHPSD compared to LPLD ablation (10, 8, and 36%, p = 0.0001). Moreover, the presence of FPI was associated with a lower AF-recurrence rate at 9-month (OR = 0.09, 95% CI 0.04–0.24, p = 0.0001).ConclusionOur prospective, observational cohort study showed that both HPSD and vHPSD RF ablation shortens procedure and RF time and results in a higher rate of FPI compared to LPLD ablation. Moreover, the use of HPSD and vHPSD ablation increased the acute and mid-term success rate. No safety concerns were raised for HPSD or vHPSD ablation in our study.

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IntroductionPulmonary vein isolation is the cornerstone of rhythm-control therapy for atrial fibrillation (AF). The very high-power, short-duration (vHPSD) radiofrequency (RF) ablation is a novel technology that favors resistive heating while decreasing the role of conductive heating. Our study aimed to evaluate the correlations between contact force (CF), power, impedance drop (ID), and temperature; and to assess their role in lesion formation with the vHPSD technique.MethodsConsecutive patients who underwent initial point-by-point RF catheter ablation for AF were enrolled in the study. The vHPSD ablation was performed applying 90 W for 4 s with an 8 ml/min irrigation rate.ResultsData from 85 patients [median age 65 (59–71) years, 34% female] were collected. The median procedure time, left atrial dwelling time, and fluoroscopy time were 70 (60–90) min, 49 (42–58) min, and 7 (5–11) min, respectively. The median RF time was 312 (237-365) sec. No steam pop nor major complications occurred. A total of 6,551 vHPSD RF points were analyzed. The median of CF, maximum temperature, and ID were 14 (10–21) g, 47.6 (45.1–50.4) °C, and 8 (6–10) Ohms, respectively. CF correlated significantly with the maximum temperature (p &lt; 0.0001). A CF of 5 g and above was associated with a significantly higher temperature compared to those lesions with a CF below 5 grams (p &lt; 0.0001). Bilateral first-pass isolation rate was 84%. The 6-month AF-recurrence rate was 7%.ConclusionThe maximum temperature and CF significantly correlate with each other during vHPSD applications. A CF ≥ 5 g leads to better tissue heating and thus might be more likely to result in good lesion formation, although this clinical study was unable to assess actual lesion sizes.