Clinical experience with contact-force and flexible-tip ablation catheter designs

Impact of open-irrigated radiofrequency catheter with contact force measurement on the efficacy and safety of atrial fibrillation ablation: a single-center direct comparison

BACKGROUND

In atrial fibrillation (AF) patients, catheter ablation of pulmonary veins (PVI) is the most effective therapeutic option to maintain sinus rhythm. To improve successful PVI, contact force-sensing (CF) catheters became routinely available. Previous studies did not clearly show superior clinical efficacy in comparison with non-CF catheters.

METHODS

We investigated consecutive patients, who underwent index PVI for AF at our hospital between 2012 and 2018. Three hundred and fifty-four patients were ablated without CF. After availability of CF catheters in 2016, 317 patients were ablated using CF. In case of crossover between the groups, follow-up was censored. The primary endpoint was any documented atrial tachycardia (AT) or atrial fibrillation > 30 s after a 3-month blanking period. Secondary endpoints were procedural characteristics and periprocedural complications.

RESULTS

There was no significant difference between the groups at baseline except hyperlipidemia. After 365 days of follow-up, 67% of patients in the CF group remained free from AF/AT recurrence compared to 59% in non-CF group (P = 0.038). In multivariable Cox regression analysis, non-CF ablation was an independent risk factor for AF recurrence besides age and persistent AF. Total fluoroscopy time (15 ± 7.6 vs. 28 ± 15.9 min) and total procedure time (114 ± 29.6 vs. 136 ± 38.5 min) were significantly lower for CF-guided PVI (P < 0.001). Complication rates did not differ between groups (P = 0.661).

CONCLUSIONS

In our study, the AT/AF recurrence rate and pulmonary vein reconnection rate is lower after CF PVI with a similar complication rate but lower total procedure time and total fluoroscopy time compared to non-CF PVI.

Radiofrequency ablation to achieve durable pulmonary vein isolation

Pulmonary vein isolation (PVI) by radiofrequency (RF) ablation is an important alternative to antiarrhythmic drugs in the treatment of symptomatic atrial fibrillation. However, the inability to consistently achieve durable isolation of the pulmonary veins hampers the long-term efficacy of PVI procedures. The large number of factors involved in RF lesion formation and the complex interplay of these factors complicate reliable creation of durable and transmural ablation lesions. Various surrogate markers of ablation lesion formation have been proposed that may provide information on RF lesion completeness. Real-time assessment of these surrogates may aid in the creation of transmural ablation lesions, and therefore, holds potential to decrease the risk of PV reconnection and consequent post-PVI arrhythmia recurrence. Moreover, titration of energy delivery until lesions is transmural may prevent unnecessary ablation and subsequent adverse events. Whereas several surrogate markers of ablation lesion formation have been described over the past decades, a 'gold standard' is currently lacking. This review provides a state-of-the-art overview of ablation strategies that aim to enhance durability of RF-PVI, with special focus on real-time available surrogates of RF lesion formation in light of the biophysical basis of RF ablation.

Updated systematic review and meta-analysis of the impact of contact force sensing on the safety and efficacy of atrial fibrillation ablation: discrepancy between observational studies and randomized control trial data

Aims

Despite widespread adoption of contact force (CF) sensing technology in atrial fibrillation (AF) ablation, randomized data suggests lack of improvement in clinical outcomes. We aimed to assess the safety and efficacy of CF-guided vs. non CF-guided AF ablation.

Methods and results

Electronic databases were searched for randomized controlled trials (RCTs) and controlled observational studies (OS) comparing outcomes of AF ablation performed with vs. without CF guidance. The primary efficacy endpoint was freedom from AF at follow-up. The primary safety endpoint was major peri-procedural complications. Secondary endpoints included procedural, fluoroscopy, and ablation duration. Subgroup analyses were performed by AF type and study design. Nine RCTs (n = 903) and 26 OS (n = 8919) were included. Overall, CF guidance was associated with improved freedom from AF [relative risk (RR) 1.10; 95% confidence interval (CI) 1.02-1.18], and reduced total procedure duration [mean difference (MD) 15.33 min; 95% CI 6.98-23.68], ablation duration (MD 3.07 min; 95% CI 0.29-5.84), and fluoroscopy duration (MD 5.72 min; 95% CI 2.51-8.92). When restricted to RCTs however, CF guidance neither improved freedom from AF (RR 1.03; 95% CI 0.95-1.11), independent of AF type, nor did it reduce procedural, fluoroscopy, or ablation duration. Contact force guidance did not reduce the incidence of major peri-procedural complications (RR 0.89; 95% CI 0.64-1.24).

Conclusion

Meta-analysis of randomized data demonstrated that CF guidance does not improve the safety or efficacy of AF ablation, despite initial observational data showing dramatic improvement. Rigorous evaluation in randomized trials is needed before widespread adoption of new technologies.

A mesh-type flexible tip catheter vs a contact force catheter for catheter ablation of atrial fibrillation: A prospective nonrandomized 1:1 matched study

INTRODUCTION

Mesh-type flexible tip (MFT) catheters allow clinicians to safely generate large radiofrequency lesions during catheter ablation of atrial fibrillation (AF), while contact force (CF) catheters provide better catheter-tissue contact. We compared the clinical outcomes of catheter ablation of AF using MFT and CF catheters in a prospective, nonrandomized manner.

METHODS

We prospectively assigned 217 patients with AF (paroxysmal AF 73.5%; male 69.1%; 59.9 ± 10.7 years old) at a 1:1 ratio to ablation with MFT catheters (FlexAbility) or CF catheters (TactiCath). The primary endpoint was AF recurrence after a single procedure; the secondary endpoint was a response to antiarrhythmic drugs.

RESULTS

After a mean follow-up of 22.3 ± 4.4 months, the clinical recurrence rate did not significantly differ between the two study groups (29.7% vs 30.2%; P = .941) (log-rank P = .838). The recurrence rate for atrial tachycardias (30.3% vs 9.7%; P = .035) and cardioversion rates (8.1% vs 1.9%; P = .024) were higher in the MFT group than CF group. At the final follow-up, sinus rhythm was maintained without antiarrhythmic drugs in 57.7% of the MFT group and 40.6% of the CF group (P = .010). No significant difference was found in the major complication rates between the two groups (0.9% vs 5.7%), although the ablation time was significantly longer in the MFT group (4192.1 ± 1080.2  vs 3583.8 ± 977.2 seconds; P < .001).

CONCLUSION

MFT and CF catheters had similar effectiveness in achieving AF rhythm control during catheter ablation, and there was no significant difference between the two catheters with regard to overall safety.

Contact Force and Ablation Index

Radiofrequency ablation of arrhythmias depends on durable lesion formation. Catheter tip-tissue contact force (CF) is a key determinant of lesion quality; excessive CF is associated with major complications, whereas insufficient CF increases the risk of electrical reconnection and arrhythmia recurrence. In recent years, CF-sensing catheters have emerged with the ability to directly measure CF and provide operators with real-time feedback. CF-guided ablation has been associated with improved outcomes in observational studies. However, randomized controlled trials have not shown any reduction in procedural durations, fluoroscopy exposure, incidence of major complications, or long-term arrhythmia recurrence with use of CF-sensing catheters.

Paroxysmal Atrial Fibrillation Catheter Ablation Outcome Depends on Pulmonary Veins Anatomy

Background

Pulmonary veins (PV) are often the trigger to atrial fibrillation (AF). Occasionally, left PVs converge on a common trunk (LCT) providing a simpler structure for catheter ablation.

Objective

To compare the clinical characteristics and outcomes of ablation in paroxysmal atrial fibrillation (PAF) of patients with or without LCT.

Methods

Case-control study of patients undergoing first-ever catheter ablation procedure for drug refractory PAF. The information was taken from patients' records by means of a digital collection instrument, and indexed to an online database (Syscardio(r)). Clinical characteristics and procedures were compared between patients with or without LCT (LCT x n-LCT), adopting a level of statistical significance of 5%. The primary endpoint associated with efficacy was lack of atrial arrhythmia over the follow-up time.

Results

One hundred and seventy two patients with PAF were included in the study, 30 (17%) LCT and 142 (83%) n-LCT. The clinical characteristics, comorbidities, symptoms scale and risk scores did not differ between the groups. There was AF recurrence in 27% of PAF patients in the n-LCT group and only 10% of patients in the LCT group (OR: 3.4 p: 0.04) after a follow-up of 34 ± 17 months and 26 ± 15 months respectively.

Conclusion

Patients with a LCT have a significantly lower recurrence rate when compared to patients without this structure. It is mandatory to report the results of AF catheter ablation as a PV anatomical variation function.

Adjunctive interpulmonary isthmus ablation has no added effects on atrial fibrillation recurrence

Objective

Data on the efficacy of adjunctive interpulmonary isthmus ablation following completion of extensive encircling pulmonary vein isolation (EEPVI) on atrial fibrillation (AF) recurrence have still been insufficient. We aimed to compare the AF recurrence between EEPVI with and without adjunctive interpulmonary isthmus ablation.

Methods

We enrolled 200 consecutive patients with paroxysmal AF (first session) who underwent EEPVI with double-Lasso technique. Patients were prospectively randomised into two groups: EEPVI with (group 1) and without (group 2) adjunctive interpulmonary isthmus ablation.

Results

No differences were found in patients’ clinical and echocardiographic backgrounds, including arrhythmia status, between the two groups. No differences were also observed in complications (two groin haematoma in both groups). All patients in both groups reached the EEPVI endpoint. The AF recurrence rate between groups 1 (32/100, 32%) and 2 (33/100, 33%; p=1.0) was quite similar during the follow-up period (45±5 months; 36–54 months). The two groups showed identical Kaplan-Meier AF-free curves (p=0.460; NS). Similar pulmonary vein (PV) reconnection incidence was observed in both groups during the second session. Durable isolation between the superior and inferior PVs was confirmed in 88% (21/27) of patients in group 1, indicating that interpulmonary isthmus ablation maintained a non-conducting state in a considerable number of patients. Nevertheless, AF recurrence was identical between the two groups.

Conclusion

The results of our study showed similar AF recurrence rates between the two groups, indicating that adjunctive interpulmonary isthmus ablation with EEPVI has no obvious effects on AF recurrence.