The benefits of ablation using TactiFlex compared with TactiCath in an ex vivo model: a face-to-face experimental comparison study.

BACKGROUND: TactiFlex is a next-generation catheter that is being used increasingly in ablation-treatment strategies. The purpose of this study was to investigate the differences in ablation lesions when the ablation power, time, and perfusion flow are varied with TactiFlex and TactiCath catheters. METHODS: The TactiFlex and TactiCath catheters were contacted perpendicularly/obliquely/parallel to the swine myocardium at varying powers (30, 40, and 50 W), time points (10, 15, 20, 25, 30, and 40 s), and forces (5, 10, 15, 20, and 30 g); the depth, width, and area of each lesion were measured, and the number of steam pops that occurred was counted. RESULTS: A total of 672 (336 lesions for each catheter) radiofrequency (RF) energy applications were delivered and 648 lesions were analyzed, excluding steam pops. The surface area and volume increased significantly with an increasing contact force for the TactiCath. The TactiCath lesions were significantly deeper than those for TactiFlex in most groups with the same power and seconds. The surface area was significantly larger when the catheters were contacted obliquely/parallel to the myocardium than perpendicularly using TactiCath, whereas the difference was less significant in the case of TactiFlex. In a 10-g contact force ablation experiment, TactiFlex did not cause pops, but TactiCath caused pops in 9.8% of cases. CONCLUSION: The TactiFlex lesions were shallower than those of TactiCath. However, TactiFlex catheters reduced the steam pops during RF applications. Those data should help clinicians understand the characteristics of the catheters and develop adequate strategies.

High-power short-duration catheter ablation of atrial fibrillation: is it really a new era? Comparison between new and old radiofrequency contact force-sensing catheters.

BACKGROUND: The clinical performance of high-power, short-duration (HPSD) pulmonary vein isolation (PVI) with the novel flexible tip TactiFlex™ (TFSE) catheter, as compared to standard-power, long-duration (SPLD) PVI using the TactiCath™ (TCSE) catheter among patients undergoing catheter ablation (CA) of atrial fibrillation (AF) is currently unknown. METHODS: We conducted a prospective, observational, single-centre study including 40 consecutive patients undergoing PVI for paroxysmal/persistent AF, using HPSD ablation with the novel TFSE catheter (HPSD/TFSE group). Based on propensity score-matching, forty patients undergoing SPLD PVI with the TCSE catheter were identified (SPLD/TCSE group). In the HPSD/TFSE group, RF lesions were performed by delivering 40-50 W for 10-20 s, while in the SPLD/TCSE group, RF power was 30-35 W, targeting a lesion size index (LSI) of 4.0-5.5. The co-primary study outcomes were time required to complete PVI and first pass isolation (FPI). RESULTS: PVI was achieved in 100% of patients in both groups, and no major adverse events were observed. Remarkably, PVI time was shorter in the HPSD/TFSE, compared to the SPLD/TCSE group(9 [7-9] min vs. 50 [37-54] min; p < 0.001), while FPI rate was non-significantly higher in the former group(91% [146/160] vs 83% [134/160]; p = 0.063). Shorter procedural (108 [91-120] min vs. 173 [139-187] min, p < 0.001), total RF (9 [7-11] min vs. 43 [32-53] min, p < 0.001), fluoroscopy times(15 [10-19] min vs. 18 [13-26] min, p = 0.014), and lower DAP (1461 [860-2181] vs. 7200 [3400-20,800], p < 0.001) were recorded in the HPSD/TFSE group. A higher average impedance drop was obtained with HPSD/TFSE CA(17[17-18]Ω vs. 16 [15-17] Ω, p < 0.001). CONCLUSIONS: In our initial clinical experience, HPSD PVI with the TFSE catheter proved faster than SPLD PVI with the TCSE catheter, at least equally effective in terms of FPI, and it was associated with greater impedance drop.

Impact of tip design and thermocouple location on the efficacy and safety of radiofrequency application.

BACKGROUND: The FlexAbility™ SE catheter has a laser-cut 8Fr 4-mm flexible tip irrigated through laser-cut kerfs with a thermocouple 0.3 mm from the distal end. The TactiCath™ SE catheter has an 8Fr 3.5-mm tip and 6-irrigation port with a thermocouple 2.67 mm proximal to the tip. We investigated the impact of these differences on the efficacy and safety of radiofrequency (RF) applications. METHODS: RF applications at a range of powers (20 W, 30 W, and 40 W), contact forces (5 g, 15 g, and 25 g), and durations (10-60 s) using perpendicular/parallel catheter orientation were performed in excised porcine hearts. Lesion characteristics and incidence of steam pops were compared. RESULTS: A total of 540 lesions were examined. The FlexAbility™ SE catheter produced smaller lesion depths (4.0 mm vs. 4.4 mm, p = 0.014 at 20 W; 4.6 mm vs. 5.6 mm, p = 0.015 at 30 W), surface areas (22.7mm2 vs. 29.2mm2 at 20 W, p = 0.005; 23.2mm2 vs. 28.7mm2, p = 0.009 at 30 W), and volumes (126.1mm3 vs. 175.1mm3, p = 0.018 at 20 W; 183.2mm3 vs. 304.3mm3, p = 0.002 at 30 W) with perpendicular catheter placement. However, no differences were observed with parallel catheter placement. Steam-pops were significantly less frequently observed with the FlexAbility™ SE catheter (4% vs. 22%, p < 0.001) irrespective of catheter direction to the tissue. Multivariate analysis showed that use of the TactiCath™ SE catheter, power ≥ 40 W, contact force ≥ 25 g, RF duration > 30 s, parallel angle, and impedance drop ≥ 20Ω were significantly associated with occurrence of steam-pops. CONCLUSIONS: The FlexAbility™ SE catheter reduced the risk of steam-pops but produced smaller lesions with perpendicular catheter placement compared to the TactiCath™ SE catheter.

Contact-Force Catheters: Efficacy Versus Safety? Case Report of 2 Atrioesophageal Fistulae.

Contact-force (CF) catheters appear to be more effective compared to standard ablation catheters for complex radiofrequency ablation including atrial fibrillation (AF) ablation when optimal CF >10 g is achieved. Some have suggested that this technology could also improve procedural safety. We report 2 cases of atrioesophageal fistulae (AEF), a rare but catastrophic complication of AF ablation. These are to our knowledge the first cases of AEF described after using CF catheters.

Characteristics of Cavotricuspid Isthmus Ablation for Atrial Flutter Guided by Novel Parameters Using a Contact Force Catheter.

INTRODUCTION: This study sought to investigate specific contact force (CF) parameters to guide cavotricuspid isthmus (CTI) ablation and compare the outcome with a historical control cohort. METHODS AND RESULTS: Patients (30) undergoing CTI ablation were enrolled prospectively in the Study cohort and compared with a retrospective Control cohort of 30 patients. Ablation in the Study cohort was performed using CF parameters >10 g and <40 g and a Force Time Integral (FTI) of 800 ± 10 g. The Control cohort underwent traditionally guided CTI ablation. Traditional parameters (electrogram and impedance change) were assessed in both cohorts. All ablations regardless of achieving targets were included in data analysis. Bidirectional CTI block was achieved in all of the Study and 27 of the Control cohort. Atrial flutter recurred in 3 (10%) patients (follow-up 564 ± 212 days) in the study cohort and in 3 (10%) patients (follow-up 804 ± 540 days) in the Control cohort. There were no major complications in either cohort. Traditional parameters correlated poorly with CF parameters. In the Study cohort, flutter recurrence was associated with significantly lower FTI and ablation duration, but was not associated with total average CF. CONCLUSION: CTI ablation can be safely performed using CF parameters guiding ablation, with similar long-term results to a historical ablation control group. Potentially CF parameters may provide adjunctive information to enable a more efficient CTI ablation. Further research is required to confirm this.

Low contact force and force-time integral predict early recovery and dormant conduction revealed by adenosine after pulmonary vein isolation.

AIM: After pulmonary vein isolation (PVI), dormant conduction (DC) is present in at least one vein in a substantial number of patients. The present study seeks to determine whether there is a relationship between poor contact forces (CF) and the presence of DC after PVI. METHODS AND RESULTS: This prospective, operator-blinded, non-randomized dual-centre trial enrolled 34 consecutive patients with paroxysmal atrial fibrillation who were candidates for PVI. Radiofrequency (RF) energy was delivered by using an irrigated-tip force-sensing ablation catheter (Tacticath, St Jude Medical) at pre-defined target power. The operators were blinded to the CF data at all times. A total of 1476 RF applications were delivered in 743 pre-defined PV segments. For each application, the precise location of the catheter was registered and the following data were extracted from the Tacisys unit: application duration, minimum contact force, maximum contact force, average contact force (CF), and force-time integral (FTI). Sixty minutes after PVI, spontaneous early recovery (ER) of the left atrium (LA) to PV conduction was evaluated. In the absence of ER, the presence of a DC was evaluated by using intravenous adenosine (ATP). In the 34 patients recruited (23 males; mean age: 62 ± 9 years), all PVs were successfully isolated. At the end of the 60 min waiting period, 22 patients demonstrated at least one spontaneous ER or DC under ATP. The mean CF and FTI per PV segment differed significantly among the different veins but the sites of ER and DC were evenly distributed. However, both the minimum, the first and the mean CF and FTI per PV segment were significantly lower in the PV segments presenting either ER or DC as compared with those without ER or DC (mean CF: 4.9 ± 4.8 vs. 12.2 ± 1.65 g and mean FTI: 297 ± 291 vs. 860 ± 81 g s, P < 0.001 for both). Using multivariate analysis, both the mean CF and the FTI per lesion remained significantly associated with the risk of ER or DC. Moreover, a CF < 5 g per PV segment predicted ER+ and DC+ with a sensitivity of 71% and specificity of 82%. In contrast, ER and DC were very unlikely if RF application was performed with a mean CF > 10 g (negative predictive value: 98.7%). CONCLUSION: Both a low CF and a low FTI are associated with the ER of the PVI and DC after PVI.