Initial clinical experience with the novel POLARx FIT cryoballoon system for pulmonary vein isolation in patients with atrial fibrillation.

Background: The POLARx FIT system (Boston Scientific, MA, USA) is a novel cryoballoon (CB) ablation technology in which the balloon diameter can be expanded from 28 to 31 mm. The aim of this study was to compare the benefits and safety of the new POLARx FIT system to those of the existing POLARx system currently in use for pulmonary vein (PV) isolation (PVI) in patients with atrial fibrillation. Methods: The first 70 consecutive patients who underwent CB-based PVI with the POLARx FIT system were retrospectively compared with 200 consecutive patients treated with the POLARx system at Sakakibara Heart Institute from October 2021 to May 2023. Results: The POLARx FIT system yielded a higher mean ± standard deviation nadir temperature in the right inferior PV (-59.2 ± 5.29 °C vs. - 62.0 ± 5.08 °C, p = 0.006), but this required a balloon size reduction to 28 mm in 30 % of cases. No significant differences were detected in the time to isolation and thaw time of any PV between the two groups. After the CB-based PVI procedure, no residual PV carina potentials were observed with the POLARx FIT system, whereas 4/20 were with the POLARx system (p = 0.04). Conclusions: The POLARx FIT system had comparable effectiveness and safety to the basic POLARx system. This technology may improve the ablation area, including the PV carina. However, the 31-mm balloon alone was not sufficient to isolate certain PVs.

Radiofrequency Current Versus Balloon-Based Ablation for Atrial Fibrillation.

The basis for selection of contemporary ablation technologies for pulmonary vein isolation (PVI) in patients with atrial fibrillation (AF) remains unclear. We compared procedural data and efficacy in a propensity score-matched cohort treated with 4 ablation technologies in a center mainly using cryoballoon (CB). A total of 819 consecutive patients with AF underwent PVI, using radiofrequency current (RFC) (65 patients), CB (693 patients), hot balloon (HB) (74 patients), and laser balloon (LB) (52 patients). Fifty patients (82% paroxysmal AF) were selected from each group according to the propensity score. Procedural data and freedom from atrial tachyarrhythmia recurrence after the index procedure were compared. All pulmonary veins were isolated in all groups. Procedure time was shorter in CB and HB groups (RFC: 148 ± 53 vs CB: 85 ± 37 vs HB: 102 ± 31 vs LB: 140 ± 28 minutes, p <0.001). RFC touch-up was most commonly required for PVI in the HB group among balloon groups (40%) (p <0.001). Total complication rate was 4% to 18% without any statistical differences between groups (p = 0.123). Phrenic nerve injury occurred most often in the CB group (16%) (p <0.001). During a mean follow-up of 21 ± 6 months, there were no significant differences among groups for freedom from atrial tachyarrhythmia recurrence after the index procedure (RFC: 68% vs CB: 78% vs HB: 76% vs LB: 76%, p = 0.440). In conclusion, all the ablation technologies facilitate safe and efficient PVI, with slight differences in the procedural data and complications.

Evaluation of linear lesion formation and thermodynamics by dragging ablation with the third-generation laser balloon.

Background: The lesion formation properties of a motorized rotational delivery (RAPID) mode, third-generation laser balloon (LB3) ablation compared to point-by-point laser ablation in patients with atrial fibrillation remain unclear. Objective: The purpose of this study was to assess lesion characteristics and thermodynamics in LB3 ablation with a RAPID mode in vitro model. Methods: Chicken muscles were cauterized using LB3 in RAPID mode with 13 W and 15 W and 50% overlapped point-by-point fashion with 7 W/30 seconds, 8.5 W/20 seconds, 10 W/20 seconds, and 12 W/20 seconds. Lesion depth, width, and continuity were compared. Lesion continuity was classified by the visible gap degree categorized from 1 (perfect) to 3 (poor). Thermodynamics and maximum tissue temperatures were assessed under infrared thermographic monitoring. Fifteen and 5 lesions were evaluated per ablation protocol for measurement of lesion size and continuity and for thermographic assessment, respectively. Results: Lesion depth and width were smaller in RAPID mode laser ablation than point-by-point laser ablation (P <.001). However, RAPID mode laser ablation revealed sufficient mean lesion depth of 5 mm or more. Lesion continuity was 1 (perfect) in all samples in RAPID mode laser ablation and point-by-point laser ablation (P = 1). Infrared thermographic observation demonstrated fast and gapless linear lesion formation with thermal stacking in RAPID mode laser ablation. Maximum tissue temperature was lower in RAPID mode laser ablation than point-by-point laser ablation (P <.001). Conclusion: RAPID mode LB3 ablation could provide fast, gapless, and acceptable lesion formation with thermal stacking and moderate tissue temperature rise.

Impact of monitoring surface temperature during pulmonary vein isolation in a second-generation hot balloon system.

BACKGROUND: A surface temperature sensor can be used to visualize the effect of hot balloon (HB) catheters. This study evaluated the efficacy and safety of a second-generation HB system with surface temperature monitoring in patients with atrial fibrillation (AF). METHODS: Twenty patients (age: 69.6 ± 9.7 years, 11 male participants) who underwent first-time pulmonary vein isolation (PVI) using a second-generation HB were included. For each pulmonary vein (PV), the acute isolation rate and effective therapeutic range of surface temperature were investigated. RESULTS: Eighty-three PVs (including three right middle PVs) were isolated in 20 patients using an HB with a surface temperature sensor. Sixty-eight PVs were isolated using the first application. Fifteen PVs (left superior PV [LSPV], n = 7 [35%]; left inferior PV, n = 2 [10%]; right superior PV, n = 3 [15%]; right inferior PV, n = 3 [15%]) showed early intraoperative reconduction and required second applications. One LSPV required radiofrequency touch-up at the carina. The optimal balloon surface temperature and application time were evaluated, and a median value of 58 °C and integral value of 1000 °C·s were identified from the receiver operating characteristic curve to be useful effective indicators. However, for LSPV, the PV potential of carina or ridge likely often remained and needed to be independently considered. There was no periprocedural complication including severe pulmonary vein stenosis. During the observation period (median: 280 days, interquartile range: 261-318 days), 17 patients (85%) achieved and maintained sinus rhythm. CONCLUSIONS: Second-generation HBs with a surface temperature sensor are expected to provide favorable outcomes in AF ablation treatment.

Prognostic predictors and echocardiographic time course after device replacement in patients treated chronically with cardiac resynchronization therapy devices.

The prognostic predictors of death or heart failure hospitalization and the echocardiographic response after initial cardiac resynchronization therapy (CRT) device replacement (CRT-r) remain unclear. We evaluated the predictors and the echocardiographic time course in patients after CRT-r. Consecutive 60 patients underwent CRT-r because of battery depletion. Patients were divided into two groups depending on the chronic echocardiographic response to CRT (left ventricular end-systolic volume [LVESV] reduction of ≥ 15%) at the time of CRT-r: CRT responders (group A; 35 patients) and CRT nonresponders (group B; 25 patients). The primary endpoint was a composite of death from any cause or heart failure hospitalization. Changes in LVESV and left ventricular ejection fraction (LVEF) after CRT-r were also analyzed. During the mean follow-up of 46 ± 33 months after CRT-r, the primary endpoint occurred more frequently in group B (group A versus group B; 8/35 [23%] patients versus 19/25 [76%] patients, p < 0.001). No significant changes in LVESV and LVEF were observed at the mean of 46 ± 29 months after CRT-r in both groups. A multivariate analysis identified echocardiographic nonresponse to CRT, chronic kidney disease, atrial fibrillation, and New York Heart Association functional class III or IV at the time of CRT-r as independent predictors of the primary endpoint in all patients. Residual echocardiographic nonresponse, comorbidities, and heart failure symptoms at the time of CRT-r predict the subsequent very long-term prognosis after CRT-r. No further echocardiographic response to CRT was found after CRT-r.

Evaluation of different ablation strategies verifying the optimal overlap ratio in point-by-point laser balloon ablation for patients with atrial fibrillation.

BACKGROUND: Optimal overlap ratio remains unclear in point-by-point laser balloon (LB) ablation. OBJECTIVE: This study sought to determine the optimal overlap strategy with target energies on the acute and chronic outcomes in LB pulmonary vein (PV) isolation (PVI). METHODS: Consecutive 38 patients (148 PVs) with atrial fibrillation underwent the first-generation LB PVI with the following protocols based on the overlap ratios for each PV anterior/posterior wall: 50%/50% (13 patients [49 PVs], group A), 50%/25% (15 patients [60 PVs], group B), and 25%/25% (10 patients [39 PVs], group C). High energies (240-255 J: 12 W / 20 seconds, 8.5 W / 30 seconds), moderate energies (200-210 J: 10 W / 20 seconds, 7 W / 30 seconds), and low-to-moderate energies (low, 165-170 J: 5.5 W / 30 seconds, 8.5 W / 20 seconds) were targeted for left PV anterior walls, right PV anterior walls, and bilateral PV posterior walls, respectively. First-pass PVI, the other procedure-related data, and atrial tachyarrhythmia recurrences were analyzed. RESULTS: First-pass PVI rate per PV was higher in group A (94%) than in group B (88%) and group C (62%) (P < .001). All PVs were finally isolated. First-pass time, total LB PVI time, complications, and atrial tachyarrhythmia recurrences during a mean follow-up of 11 ± 5 months did not differ between the groups. A few residual gaps after first-pass LB ablations were found for PV anterior walls even in group A and group B. CONCLUSION: Sufficiently overlapped LB ablation promises a high rate of first-pass PVI without adverse outcomes. High energy could be required for PV anterior walls.

Comparison of dragging ablation and point-by-point ablation with a laser balloon on linear lesion formation.

INTRODUCTION: Lesion size and continuity in dragging laser balloon (LB) ablation, which may enable fast and durable pulmonary vein isolation for atrial fibrillation, are unknown. We evaluated the differences in size and continuity of linear lesions formed by dragging ablation and conventional point-by-point ablation using an LB in vitro model. METHODS AND RESULTS: Chicken muscles were cauterized using the first-generation LB in dragging and point-by-point fashion. Dragging ablation was manually performed with different dragging speeds (0.5-2°/s) using an overlap ratio of the beginning and last site during one application at 12 W/20 s and 8.5 W/30 s. Point-by-point ablation was performed with 25% and 50% overlap ratios at six energy settings (5.5 W/30 s to 12 W/20 s). Lesion depth, width, and continuity were compared. Lesion continuity was assessed by the surface and deep visible gap degree categorized from 1 (perfect) to 3 (poor). Twenty lesions were evaluated for each ablation protocol. Lesion depth and width in dragging ablation at high power (12 W) were comparable with most measurements in point-by-point ablation. Lesion depth and width were smaller at faster-dragging speed and lower power (8.5 W) in dragging ablation. The surface visible gap degree was better in dragging ablation at all dragging speeds than a 25% overlapped point-by-point ablation (p < .001). CONCLUSION: Dragging LB ablation at high power provides deep and continuous linear lesion formation comparable with that of point-by-point LB ablation. However, lesion depth and width depending on the dragging speed and power.

Gender difference in arrhythmic occurrences in patients with nonischemic dilated cardiomyopathy and implantable cardioverter-defibrillator.

Previous studies indicated that women were less likely to experience ventricular arrhythmia recurrence than men among patients with coronary artery disease and implantable cardioverter defibrillator (ICD). However, it is not clear whether the risk for ventricular tachyarrhythmia is gender-dependent in patients with nonischemic dilated cardiomyopathy. This study included 173 consecutive nonischemic dilated cardiomyopathy patients with a left ventricular ejection fraction of <45% (122 men and 51 women), who received ICD therapy between 1990 and 2008. The average follow-up period was 33 +/- 28 months. There was no significant difference in event-free rates of appropriate ICD therapy between genders for all patients (P = 0.15) and by indication of ICD (primary prevention: P = 0.43, secondary prevention: P = 0.24). There was also no significant difference in event-free rates of electrical storm between genders (P = 0.17). In high-risk patients with nonischemic dilated cardiomyopathy who received ICD, there was no gender difference in the incidence of appropriate ICD therapy or electrical storm.

Bi-focal atrial tachycardia mimicking atrial fibrillation: fusion and interference between two distinct tachycardias.

Irregular tachycardias mimicking atrial fibrillation (AF) have previously been described. We report a case of a 60-year-old man with an antiarrhythmic drug-resistant atrial tachycardia (AT) mimicking AF. The tachycardia consisted of two distinct ATs with interference of one repetitive AT with another sustained AT. Radiofrequency (RF) ablation of two distinct right atrial foci eliminated the irregular tachycardia. Although catheter-based pulmonary vein isolation has become a popular therapeutic approach for patients with symptomatic AF, careful evaluation of the intracardiac recordings in the patients undergoing RF ablation for AF is important.

Amiodarone decreases plasma brain natriuretic peptide level in patients with heart failure and ventricular tachyarrhythmia.

Brain natriuretic peptide (BNP) is a powerful neurohormonal marker of left ventricular function and prognosis. Amiodarone either has no effect or improves the haemodynamics in patients with left ventricular dysfunction, but its effect on BNP is unknown. This study evaluated the effect of amiodarone on plasma BNP level in patients with heart failure and ventricular tachyarrhythmia. Plasma BNP level was studied in 46 patients with heart failure ventricular tachyarrhythmia, before (baseline) and at week 2 and months 1, 3 and 6 of amiodarone treatment. In addition, 21 patients with heart failure and ventricular tachyarrhythmia, who received an implantable cardioverter defibrillator, but not amiodarone, were studied on the same schedule. All patients had previously received potent vasodilator and beta-blocker therapy. Echocardiography and Holter monitoring were also performed. Amiodarone significantly decreased plasma BNP levels at week 2 to month 6 during therapy. Heart rates and frequencies of premature ventricular complexes were markedly reduced by amiodarone. Echocardiographic findings did not show a change in left ventricular end-diastolic dimensions, despite a slight increase in fraction shortening at month 6 during amiodarone therapy. The above parameters showed no change in patients without amiodarone. The effect of heart rate, premature ventricular complexes, fraction shortening, serum creatinine or thyroid stimulating hormone level was not significantly associated with decrease in BNP level during amiodarone therapy by a multivariate analysis. Among amiodarone-treated patients, mortality was higher in 24 with BNP levels >/=100 pg/ml at month 6 than in 22 with BNP levels <100 pg/ml during a mean follow-up period of 31 months. Amiodarone appears to have a decreasing effect on plasma BNP level, as well as an antiarrhythmic effect, in patients with heart failure and ventricular tachyarrhythmia.