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Background: Patients may develop atrial tachycardia (AT) after left atrial (LA) ablation of persistent atrial fibrillation (AF). Methods: The population consisted of 101 consecutive patients (age = 64.3 ± 8.7 years, 70 males (69%), LA = 4.6 ± 0.8 cm, ejection fraction = 48.5 ± 16%) undergoing their initial procedure for persistent AF. After pulmonary vein isolation, patients either underwent posterior LA isolation (n = 50; study group) or linear ablation at the LA roof with verification of conduction block (n = 51; control group). Results: A repeat procedure was performed in 17 (34%) and 28 (55%) patients in the study and control groups, respectively (p = 0.02). Patients in the study group were less likely to develop AT (9/50 [18%] vs. 18/51 [35%]; p = 0.02), roof-dependent (1/50 [2%] vs. 8/51 [16%]; p = 0.008), and multi-loop AT (6/50 [12%] vs. 14/51 [27%]; p = 0.03) as compared to controls. Among various factors, only posterior LA isolation was associated with a lower likelihood of AT recurrence and roof tachycardia at redo procedure (OR, 0.37; 95% CI, 0.1 to 1.00, p = 0.05, and OR, 0.1, 95% CI, 0.01 to 0.96; p < 0.05, respectively). Conclusions: In patients with persistent AF, posterior LA isolation is associated with a lower risk of a redo procedure, roof-dependent macro-reentry, and post-ablation AT in general as compared to controls who only received roof ablation. Posterior LA isolation also obviates the need for pacing maneuvers, and may be a more definitive endpoint than linear ablation at the LA roof. [ABSTRACT FROM AUTHOR]

Background: Catheter ablation is routinely used to treat scar-related atrial tachycardia (s-AT). Conventional ablation often involves creating anatomical "lines" that transect myocardial tissue supporting reentry. This can be extensive, creating iatrogenic scar as a nidus for future reentry, and may account for arrhythmia recurrence. High-density mapping may identify "narrower isthmuses" requiring less ablation, with ripple mapping proven to be an effective approach in identifying. This trial explores whether ablation of narrower isthmuses in s-AT, defined using ripple mapping, results in greater freedom from arrhythmia recurrence compared to conventional ablation. Methods: The Ripple-AT-Plus trial (registration ClinicalTrials.gov, NCT03915691) is a prospective, multicentre, single-blinded, randomised controlled trial with 12-month follow-up. Two hundred s-AT patients will be randomised in a 1:1 fashion to either "ripple mapping-guided isthmus ablation" vs conventional ablation on the CARTO3 ConfiDENSE system (Biosense Webster). The primary outcome will compare recurrence of any atrial arrhythmia. Multicentre data will be analysed over a secure web-based cloud-storage and analysis software (CARTONETTM). Conclusion: This is the first trial that considers long-term patient outcomes post s-AT ablation, and whether targeting narrower isthmuses in the era of high density is optimal. [ABSTRACT FROM AUTHOR]

Purpose: Based on the high rate of coexisting atrial fibrillation (AF) and atrial flutter (AFL), prophylactic cavotricuspid isthmus ablation (CTIA) adjunctive to AF ablation has recently been attempted in patients with AF and without AFL. The present study aimed to determine the rates of AFL occurrence and CTI reconduction after performing CTI ablation adjunctive to AF ablation.Methods: We analyzed the data of 3833 consecutive patients with AF, who underwent prophylactic CTIA with AF ablation between 2009 and 2020.Results: In all patients, CTIA and AF ablations were successful. Clinical AFL occurred in seven patients (0.18%, 7/3,833), and the observed rate was lower than those reported for cases of AF ablation without CTIA and for those of CTIA for pure AFL. A second ablation was needed in 745 patients at a median of 253 days (25 and 75 percentiles, 116 and 775 days) after the first ablation. In 12.1% (90/745) of the patients, CTI reconduction was observed. The reconduction rate was lower than that previously reported for CTIA for pure AFL.Conclusions: The present retrospective study found acceptably low rates of clinical AFL occurrence and CTI reconduction following prophylactic CTIA performed with AF ablation, which was supported by the findings obtained after performing a comparison of the rates with those of other ablations (AF ablation only and CTIA for pure AFL). Considering the high correlation between AF and AFL, the present study provided information regarding the efficacy of adjunctive CTIA. [ABSTRACT FROM AUTHOR]

Background: Catheter based “maze” procedures for atrial fibrillation have been hampered by difficult creation and evaluation of continuous and transmural linear lesions. Our aim was to develop an online evaluation method for effective lesion creation based on conventional techniques and using the multipolar ablation catheter, already in place. Methods and Results: We created 15 linear lines in right atria of 13 anesthetized sheep using three multipolar catheter designs (8 × 4 mm 7 Fr, 4 × 6 mm 7 Fr, 8 × 4 mm 3.7 Fr). The lesions were placed on the right posterolateral wall between the orifices of the superior and inferior vena cava. Radiofrequency energy was applied in the temperature-controlled mode to prespecified endpoints (electrogram amplitude decrease to ≤50%; pacing threshold increase by ≥100%; split potentials indicating conduction block). Macroscopically transmural and continuous lesions were achieved in only 3 experiments (29 ± 12 mm × 5 ± 1 mm), all created by 3.7 Fr octapolar catheters inserted through long sheaths. Preset temperature was reached in 96% of the electrodes (vs. 64% in the non-effective experiments; p < 0.01). Electrogram amplitude decrease (to ≤50%) and pacing threshold increase (by ≥100%) did not predict effectiveness. The only criterion that could reliably predict transmural continuous necrosis at histology was the development of split potentials (p ≤ 0.05). Conclusions: Effective creation of linear lesions is difficult. Pliable catheters that conform to the endocardial contour give the best results. The only endpoint that reliably predicted histological transmural continuous necrosis was development of split potentials indicating conduction block. [ABSTRACT FROM AUTHOR]

Pre-ablation impedance was evaluated for its ability to detect electrode-tissue contact and allow creation of long uniform linear lesions with a multi-electrode ablation catheter. The study consisted of 2 parts, both of which used the in vivo pig thigh muscle model. In part 1, a 7 Fr. multi-electrode catheter was held in 3 electrode-tissue contact conditions: (1) non-contact; (2) light contact with a 30[emsp4 ]g downward force; and (3) tight contact with a 90[emsp4 ]g downward force. Impedances were measured in unipolar, modified unipolar and bipolar configurations using a source with frequencies from 100[emsp4 ]Hz to 500[emsp4 ]kHz. Compared with non-contact, the impedance increased 35±22±% with 30[emsp4 ]g contact pressure and 68±40±% when the contact pressure was increased to 90[emsp4 ]g across the range of frequencies studied. In part 2, the same catheter was held against the tissue with different forces. Pre-ablation impedance was measured using a 10[emsp4 ]kHz current. Phased radiofrequency energy was applied to the 5 electrodes simultaneously using 10[emsp4 ]W power at each electrode for 120[emsp4 ]s. A total of 32 linear lesions were created. The lesion dimensions correlated with pre-ablation impedance. A unipolar impedance ≥190[emsp4 ]Ω indicates 95±% possibility to create a uniform linear lesion of at least 3[emsp4 ]mm depth with our ablation system. We conclude that pre-ablation impedance may be a useful indicator for predicting electrode-tissue contact and the ability to create a continuous and transmural linear lesion with a multi-electrode catheter. [ABSTRACT FROM AUTHOR]