Adherence to the CLOSE Protocol and Low Baseline Generator Impedance Are Independent Predictors of Durable Pulmonary Vein Isolation.

Background: Atrial fibrillation (AF) recurrence after pulmonary vein isolation (PVI) is predominantly attributed to pulmonary vein reconnection (PVR). Predictors of AF recurrence have been widely studied; however, data are scarce on procedural parameters that predict chronic PVR. We aimed to study PVR rates and predictors of PVR. Methods: We retrospectively included 100 patients who underwent repeated ablation due to AF recurrence after initial PVI with the CARTO system. PVR was determined during the repeated procedure by electrophysiological evaluation, and initial procedural characteristics predicting PVR were studied, including adherence to the CLOSE protocol, use of high power, first-pass isolation (FPI), and baseline generator impedance (BGI). Results: Thirty-eight patients underwent initial CLOSE-guided PVI, and sixty-two underwent initial non-CLOSE PVI. A repeat procedure was performed 23 ± 16 months after the initial procedure. In total, PVR was found in 192 of 373 PVs (51.5%), and all PVs were isolated in 17/100 (17%) patients. Factors associated with all PVs being isolated were adherence to the CLOSE protocol, a higher power setting, the presence of bilateral FPI, and lower BGI (88% vs. 28%, p < 0.0001; 37.5 W vs. 30 W, p = 0.0276; 88.2% vs. 40.4%, p = 0.0007; and 127.6 Ω vs. 136.6 Ω, p = 0.0027, respectively). In initial procedures with adherence to the CLOSE protocol, the FPI rate was significantly higher (73.7% vs. 25%, p < 0.0001), while there were no significant differences in terms of procedure time and left atrial dwell time (81 vs. 85 min, p = 0.83; and 60 vs. 58 min, p = 0.08, respectively). BGI ≥ 130 Ω (AUC = 0.7403, sensitivity: 77.1%, specificity: 68.8%, p = 0.0032) was associated with a significantly higher probability of PVR (OR = 6.757; p < 0.0001). In multivariable analysis, independent predictors for PVR were non-adherence to the CLOSE protocol and BGI ≥ 130 Ω. Conclusions: Our findings indicate that adherence to the CLOSE protocol and baseline generator impedance < 130 Ω during AF ablation are independent predictors of PVI durability.

Long-Term Durability of High- and Very High-Power Short-Duration PVI by Invasive Remapping: The HPSD Remap Study.

BACKGROUND: High-power short-duration ablation has shown impressive efficacy and safety for pulmonary vein isolation (PVI); however, initial efficacy results with very high power short-duration ablation were discouraging. This study compared the long-term durability of PVI performed with a 90- versus 50-W power setting. METHODS: Patients were randomized 1:1 to undergo PVI with the QDOT catheter using a power setting of 90 or 50 W. Three months after the index procedure, patients underwent a repeat electrophysiology study to identify pulmonary vein reconnections. Patients were followed for 12 months to detect AF recurrences. RESULTS: We included 46 patients (mean age, 64 years; women, 48%). Procedure (76 versus 84 minutes; P =0.02), left atrial dwell (63 versus 71 minutes; P =0.01), and radiofrequency (303 versus 1040 seconds; P <0.0001) times were shorter with 90- versus 50-W procedures, while the number of radiofrequency applications was higher with 90 versus 50 W (77 versus 67; P =0.01). There was no difference in first-pass isolation (83% versus 82%; P =1.0) or acute reconnection (4% versus 14%; P =0.3) rates between 90 and 50 W. Forty patients underwent a repeat electrophysiology study. Durable PVI on a per PV basis was present in 72/78 (92%) versus 68/77 (88%) PVs in the 90- and 50-W energy setting groups, respectively; effect size: 72/78-68/77=0.040, lower 95% CI=-0.051 (noninferiority limit=-0.1, ie, noninferiority is met). No complications occurred. There was no difference in 12-month atrial fibrillation-free survival between the 90- and 50-W groups (P =0.2). CONCLUSIONS: Similarly high rates of durable PVI and arrhythmia-free survival were achieved with 90 and 50 W. Procedure, left atrial dwell, and radiofrequency times were shorter with 90 W compared with 50 W. The sample size is too small to conclude the safety and long-term efficacy of the high and very high-power short-duration PVI; further studies are needed to address this topic. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT05459831.

Incidence and predictors of stroke and silent cerebral embolism following very high-power short-duration atrial fibrillation ablation.

AIMS: Cerebral thrombo-embolism is a dreaded complication of pulmonary vein isolation (PVI) for atrial fibrillation; its surrogate, silent cerebral embolism (SCE) can be detected by diffusion-weighted brain magnetic resonance imaging (bMRI). Initial investigations have raised a concern that very high-power, short-duration (vHPSD; 90 W/4 s) temperature-controlled PVI with the QDOT Micro catheter may be associated with a higher incidence of SCE compared with low-power long-duration ablation. We aimed to assess the incidence of procedural complications of vHPSD PVI with an emphasis on cerebral safety. METHODS AND RESULTS: We enrolled 328 consecutive patients undergoing their PVI procedure using vHPSD. A subgroup of 61 consecutive patients underwent diffusion-weighted bMRI within 24 h of the procedure, and incidence and predictors of SCE were studied. The mean procedure time and left atrial dwell time for the overall cohort were 69.6 ± 24.1 and 46.5 ± 21.5 min, respectively. First-pass isolation was achieved in 82%. No stroke or transient ischaemic attack occurred. Silent cerebral embolism was identified in 5 of 61 patients (8.2%). Silent cerebral embolism following procedures was significantly associated with lower baseline generator impedance (105.8 vs. 112.6 Ω, P < 0.0001) and with intermittent loss of catheter-tissue contact during ablation (14.1% vs. 6.1%, P < 0.0001). CONCLUSION: Very high-power, short-duration PVI is a safe technique with an excellent acute success rate. Silent cerebral embolism incidence in our cohort was below the previously reported range, with no clinically overt cerebral complications. Lower baseline generator impedance and loss of contact during ablation may contribute to a higher risk of SCEs.

Use of a new non-contrast-enhanced BOOST cardiac MR sequence before electrical cardioversion or ablation of atrial fibrillation-a pilot study.

Introduction: Left atrial appendage (LAA) thrombus is the most common source of embolization in atrial fibrillation (AF). Transesophageal echocardiography (TEE) is the gold standard method for LAA thrombus exclusion. Our pilot study aimed to compare the efficacy of a new non-contrast-enhanced cardiac magnetic resonance (CMR) sequence (BOOST) with TEE for the detection of LAA thrombus and to evaluate the usefulness of BOOST images for planning radiofrequency catheter ablation (RFCA) compared with left atrial (LA) contrast-enhanced computed tomography (CT). We also attempted to assess the patients' subjective experiences with TEE and CMR. Methods: Patients with AF undergoing either electrical cardioversion or RFCA were enrolled. Participants underwent pre-procedural TEE and CMR scans to evaluate LAA thrombus status and pulmonary vein anatomy. Patient experiences with TEE and CMR were assessed using a questionnaire developed by our team. Some patients scheduled for RFCA also had pre-procedural LA contrast-enhanced CT. In such cases, the operating physician was asked to subjectively define the quality of the CT and CMR scan on a scale of 1-10 (1 = worst, 10 = best) and comment on CMR's usefulness in RFCA planning. Results: Seventy-one patients were enrolled. In 94.4%, both TEE and CMR excluded, and in 1 patient, both modalities reported the presence of LAA thrombus. In 1 patient, TEE was inconclusive, but CMR excluded LAA thrombus. In 2 patients, CMR could not exclude the presence of thrombus, but in 1 of those cases, TEE was also indecisive. During TEE, 67%, during CMR, only 1.9% of patients reported pain (p < 0.0001), and 89% would prefer CMR in case of a repeat examination. The quality of the left atrial contrast-enhanced CT scans was better compared with the image quality of the CMR BOOST sequence [8 (7-9) vs. 6 (5-7), p < 0.0001]. Still, the CMR images were useful for procedural planning in 91% of cases. Conclusion: The new CMR BOOST sequence provides appropriate image quality for ablation planning. The sequence might be useful for excluding larger LAA thrombi; however, its accuracy in detecting smaller thrombi is limited. Most patients preferred CMR over TEE in this indication.