Porous tip radiofrequency ablation catheter reduced heart failure‐related complications and healthcare resource utilization in paroxysmal atrial fibrillation patients

Abstract Introduction A 56‐hole porous tip radiofrequency catheter was developed to provide more uniform cooling with less fluid delivery than a prior 6‐hole irrigated design. This study aimed to evaluate the impact of contact force (CF) ablation with the porous tip on complications (congestive heart failure [CHF] and non‐CHF related), healthcare resource utilization, and procedural efficiency in patients undergoing de novo paroxysmal atrial fibrillation (PAF) ablations in a real‐world setting. Methods Consecutive de novo PAF ablations were performed between February 2014 and March 2019 by six operators at a single US academic center. The 6‐hole design was used through December 2016 with the 56‐hole porous tip adopted in October 2016. The outcomes of interest included symptomatic CHF presentation and CHF‐related complications. Results Of 174 patients who were included, mean age was 61.1 ± 10.8 years, 67.8% were male, and 25.3% had a history of CHF. Ablation with the porous tip catheter significantly decreased fluid delivery (1177 vs. 1912 mL with the 6‐hole design; p < .0001). CHF‐related complications within 7 days, particularly fluid overload, were substantially reduced with the porous tip (15.2% vs. 5.3% of patients; p = .0281) and the proportion of patients with symptomatic CHF presentation within 30 days postablation was significantly lower (14.7% vs. 32.5%; p = .0058). Conclusion The 56‐hole porous tip led to significantly reduced CHF‐related complications and healthcare utilization in PAF patients undergoing CF catheter ablation when compared to the prior 6‐hole design. This reduction likely results from the significant decrease in fluid delivery during the procedure.


| INTRODUC TI ON
Radiofrequency (RF) catheter ablation is an effective and minimally invasive treatment option for patients with atrial fibrillation (AF). 1 The benefits of AF ablation in heart failure (HF) patients with reduced and preserved ejection fractions have recently been demonstrated in the CASTLE-AF and CABANA trials, respectively. 2,3 In the former, ablation was associated with a significantly lower occurrence of a composite endpoint of death from any cause or hospitalization for worsening HF compared to medical therapy (28.5% vs. 44.6%, respectively) in patients with a left ventricular ejection fraction ≤35% over a median follow-up of 37.8 months. 2 In the latter, after a median follow-up of 48.5 months, AF ablation was responsible for a 36% relative reduction in a composite endpoint of death, disabling stroke, serious bleeding, or cardiac arrest, as well as a 43% relative reduction in all-cause mortality compared to drug therapy in a cohort of HF patients who mostly had preserved left ventricular function. 3 Despite the benefits of AF ablation in HF patients, fluid management during the procedure is critical in these patients to prevent HF-related complications.
Efforts to improve the outcomes of catheter ablation have led to continuous improvements in catheter design. Compared with nonirrigated catheters, irrigated tips allow for longer and deeper lesions by preserving a low electrode temperature during RF application. 4,5 Nonetheless, catheter irrigation can result in substantial fluid delivery and risk of fluid overload, particularly in vulnerable patients with preexisting HF. [6][7][8] A 56-hole porous tip RF catheter was originally developed to provide more uniform cooling with less fluid delivery than a prior 6-hole irrigated design in order to reduce fluid overload and associated complications related to congestive heart failure (CHF).
The safety and acute effectiveness of the porous tip design for paroxysmal atrial fibrillation (PAF) ablations have been established for contact force (CF)-sensing catheters in the SMART-SF trial. 6 Compared to the SMART-AF study of the prior 6-hole CF catheter, 9 reductions in procedure time (18.7%), ablation time (14.2%), and total fluoroscopy time (55.2%) were observed. A recent meta-analysis also reported significantly lower procedural times and irrigation fluid volume for ablations performed with the porous CF catheter versus those performed with the conventionally irrigated CF catheter. 10 Complication rates were low and similar for both catheters. 10 The objective of the current study was to evaluate the impact of CF ablation with the porous tip versus the conventionally irrigated tip on complications (CHF and non-CHF related), healthcare resource utilization, and procedural efficiency among patients undergoing de novo PAF ablations in a real-world clinical setting.

| Patient population
The study population consisted of consecutive adult patients aged 21 years or older who underwent a de novo PAF catheter ablation at the study site with one of the two study catheters-THERMOCOOL Patients with a history of persistent AF and/or belonging to a vulnerable population were excluded. Pulmonary veins (PVs) were isolated by wide-area circumferential ablation using the dragging technique. Respiratory gating was utilized. Contact force between 5 and 20 g was sought while maintaining 35 Watts through the left atrium. Pacing of the PVs was performed to verify lack of capture. Entrance block at each PV was then verified by remapping.

| Patient follow-up
Patients were followed up for a year after ablation for safety, symptoms, and treatments. Routine follow-up visits were scheduled at 7-10 days, 4-6 weeks, and yearly thereafter.

| Study outcomes
The primary outcome was symptomatic CHF presentation, defined as a new diuretic prescription, an increase in dosage of a diuretic to alleviate exacerbation, and/or a CHF-related hospital, emergency room, or clinic visit within 30 days postprocedure. Secondary outcomes included complications (CHF and non-CHF related) within 7 days and documented fluid overload within 30 days. Procedural efficiency and ablation details were also of interest.

| Statistical analysis
All available baseline patient characteristics, procedural details, and safety outcomes were summarized by descriptive statistics and compared across catheter cohorts using chi-square tests for categorical measures and t-tests for continuous measures.
Logistic regression modeling was utilized to compare the likelihood of a symptomatic CHF presentation within 30 days postablation between the catheter cohorts, while simultaneously adjusting for baseline CHF and any additional patient characteristics that were associated with the outcome at a significance level of 0.15.
Statistical analysis was performed using SAS software, version 9.4 (SAS Institute Inc.). Patients' mean age was 61.1 ± 10.8 years and 67.8% were male. The mean preablation AF duration was 31.8 ± 42.9 months.

| Baseline characteristics
Hypertension was the most prevalent comorbidity (78.7%) and 25.3% of the patients had a history of CHF at baseline.
Most patient characteristics were similar across catheter cohorts (Table 1). However, cardiomyopathy and oral anticoagulation utilization were higher at baseline in the ST versus STSF cohorts, while a finding of left atrial enlargement was less prevalent (35.4% vs. 18.9%, 97.5% vs. 84.2%, and 3.8% vs. 12.6%, respectively). Left atrial enlargement was based on a standardized and automated electrocardiogram criteria consisting of a P wave that was >0.1 s duration in leads I and II and that was biphasic with a marked negative deflection in V1.

| Primary outcome: Symptomatic CHF presentation
The primary outcome of symptomatic CHF presentation within 30 days postablation was significantly lower in the STSF cohort than the ST cohort (14.7% vs. 32.5%; p = .0058) (Figure 1). This reduction persisted after controlling for baseline CHF and age via multivariable logistic regression (odds ratio = 0.37; p = .0103) ( Table 3). No additional patient characteristics or procedural details were significantly associated with this outcome.  and 538 mL, which is expected to further reduce CHF-related complications. 15,16 The marked decrease in the incidence of fluid overload following STSF ablations-more than 400% within 7 days, and approximately 200% within 30 days-suggests that the porous tip catheter may play an important role in easing the associated impacts on both the patient and payers, particularly considering that a considerable proportion of AF patients have comorbidities that place them at a higher risk of fluid overload. 1 The potential magnitude of the economic benefit can be estimated from the results of a retrospective study that reported a 29% longer length of stay and 43% higher per-visit hospital cost among inpatients with diagnosis codes for fluid overload in a large hospital database. 17 Low and similar complication rates for STSF and ST ablations have been reported by prior studies. Major complications are uncommon with either catheter, with rates varying between 0% and 2.7% in the available literature. [11][12][13] Rates of minor complications are slightly higher, ranging from 0% to 5%. 11,12 Consistent with these studies, we found no difference in non-CHF complication rates across catheter cohorts. The rates observed in the present study (16.5% and 17.9% for the ST and STSF, respectively) were TA B L E 3 Multivariable logistic regression model of symptomatic congestive heart failure presentation within 30 days.

| Limitations
The primary limitations of this study are associated with the non-

| CON CLUS ION
In a real-world setting, a porous catheter tip led to significantly reduced CHF-related complications and healthcare utilization in PAF patients undergoing CF catheter ablation compared to a traditional 6-hole irrigated ablation catheter. This reduction likely resulted from the significant decrease in fluid that was delivered via the ablation catheter during the procedure. This finding has the potential to F I G U R E 2 All-cause and cardiovascular-related hospitalizations after ablation procedure. SD, standard deviation; ST, THERMOCOOL SMARTTOUCH ® ; STSF, THERMOCOOL SMARTTOUCH ® SF. evoke a substantial positive economic impact in addition to the positive impact on patient safety.

ACK N OWLED G M ENTS
The authors would like to acknowledge the substantial contributions of Larry Gache to the statistical design and analysis in this study, and to Diogo Ribeiro for medical writing support.

FU N D I N G I N FO R M ATI O N
This study was funded by Biosense Webster, Inc.

CO N FLI C T O F I NTER E S T S TATEM ENT
Alexandru Costea is a speaker for Biosense Webster, Inc. and Biotronik.
LM Boo is an employee of Biosense Webster, Inc., the study sponsor.
TD Hunter is an employee of CTI Clinical Trial & Consulting, which is a consultant to Biosense Webster, Inc., the study sponsor. The other authors have no conflicts of interest relating to this manuscript.

DATA AVA I L A B I L I T Y S TAT E M E N T
The data that support the findings of this study are available from the corresponding author upon reasonable request.