Ultrasound guidance for femoral venous access in patients undergoing pulmonary vein isolation: A quasi‐randomized study

Routine ultrasound (US) guidance for femoral venous access to decrease vascular complications of atrial fibrillation (AF) ablation procedures has been advocated. However, the benefit has not been unequivocally demonstrated by randomized‐trial data.


| INTRODUCTION
Catheter ablation for atrial fibrillation (AF) is by far the most often performed cardiac ablation procedure worldwide. [1][2][3][4] Although the complication rate of AF ablation procedures is low, they may prolong hospitalization and often interfere with the quality of life of the patients. 5,6 The most frequent complications of these procedures are related to vascular access ranging in frequency from 1% to 13%. 5,7,8 Traditionally, femoral vein puncture is guided by palpation of the femoral artery below the inguinal ligament and the needle is inserted next to the pulsation to target the femoral vein. However, the position of the femoral vessels in relation to each other is variable. 9 Vascular ultrasound (US) guidance can clarify the anatomy of the femoral vessels, identify variations that may interfere with the puncture, and thereby decrease access-related complications ( Figure 1).
Routine use of US to guide femoral access during electrophysiology (EP) procedures has been advocated, however, its universal adoption has been hampered by the lack of randomized-trial data unequivocally showing its benefit. Prior meta-analyses demonstrated that US guidance for femoral vein punctures in EP procedures reduces the rate of both major and minor vascular complications. 10,11 To date, only one randomized controlled trial (RCT) investigated the potential benefits associated with the use of US for femoral venous access in patients undergoing AF ablation procedures. 12 Although US guidance improved intraprocedural outcomes, there was no difference in the major complication rates presumably due to the lowerthan-expected complication rate in the conventional arm.
We aimed to provide a quasi-randomized comparison of the two techniques taking advantage of the fact that early in our experience with the use of US-guided access only one of our two procedure rooms was equipped with a vascular US probe.

| Patient population
Consecutive patients older than 18 years undergoing pulmonary vein isolation (PVI) for AF with standard indications on uninterrupted anticoagulant treatment were prospectively included. Patients on novel oral anticoagulants did not skip any dose even in the morning of the procedure. The target international normalized ratio for those who were taking vitamin K antagonist was 2.0-3.0. We excluded patients referred for a redo procedure.

| Study endpoints
The primary endpoint was the composite rate of major and minor vascular complications. The frequency of prolonged hospitalization was also compared between the two groups. Major vascular complications included groin hematoma, arteriovenous fistula, or pseudoaneurysm. Hematoma was considered as a major vascular complication if it met type 2 or higher Bleeding Academic Research Consortium (BARC) criteria (requiring nonsurgical, medical intervention by a health care professional; leading to hospitalization or increased level of care, or prompting evacuation). The type 1 BARC criteria define bleeding as nonactionable and not causing the patient to seek unscheduled medical attention, and hematomas that met these criteria were considered minor vascular complications. 13 The definition of prolonged hospitalization in this study referred to a patient's stay in the hospital more than one night following the completion of the ablation procedure.
The protocol of the study is in accordance with the Declaration of Helsinki and the study protocol was approved by the regional ethics committee. All patients provided written informed consent.

| Statistical analysis
Parametric data are presented as mean and standard deviation.
Categorical data are presented as percentage. Data were analyzed according to their normal distribution on the Shapiro goodness-of-fit test. Categorical variables were compared using χ 2 test. p < .05 was considered statistically significant in all analyses. Statistical analyses were performed using SPSS 24 software (SPSS Inc.).

| RESULTS
Of 457 patients 199 were allocated to US-guided puncture group, while the conventional, palpation-based approach was performed in 258 cases.
There was no difference in patients' baseline characteristics between the groups ( 1.01%, p = .001) vascular complications. The absolute risk reduction of minor/major vascular complications was 9.62% equated to a relative risk reduction (RRR) of 82.71%, and a number needed to treat of 10 to prevent one bleeding event. The decrease in the rate of prolonged hospitalization was also statistically significant (5.04% vs. 1.01%, p = .032).
Results are shown in Figure 2 and Table 2.

| DISCUSSION
In this prospective, quasi-randomized comparison US-guided femoral vein puncture improved the safety of AF ablation procedures compared with the conventional, palpation-based technique. US guidance was associated with lower composite, major and minor vascular complication rates.
The most common complications of the EP procedures are related to the vascular access. 5,6 AF ablations carry the highest risk for these types of events, which can be explained by the use of large and multiple sheaths and uninterrupted, periprocedural anticoagulant treatment. 7,14,15 Vascular US guidance during femoral access provides real-time visualization of the inguinal vessels and the surrounding structures, identifying anatomical variations. 16 Additionally, it allows following of the needle during the puncture to guide and correct its course. 17 Several nonrandomized, observational studies showed the superiority of the US-guided technique in the rate of vascular complications of AF ablation, [18][19][20] however the only one RCT failed to meet its primary endpoint. 12 A retrospective trial involving 3420 patients undergoing PVI for AF showed, that US-guided femoral vein puncture improves the safety profile of PVI procedures by reducing total, major, and minor vascular complications. 18 Although the rate of these complications was low even in the non-US group (1.7%), the benefit from US guidance was clearly demonstrated by a 70.6% RRR.
In the multicentre ULTRA-FAST RCT 320 patients, who underwent an AF ablation procedure were randomized to US-guided or conventional vein puncture. The study was prematurely terminated F I G U R E 2 Comparison of major complications, minor complications, and prolonged hospitalization between conventional versus ultrasound (US)-guided femoral vein puncture group.
T A B L E 2 Comparison of major complications, minor complications, and prolonged hospitalization between conventional versus ultrasoundguided femoral vein puncture group. before meeting its primary endpoint of reduction in vascular complications due to substantially lower-than-expected complication rates, which doubled the population size needed to maintain statistical power. 12 23 and is cost-effective. 24 In spite of the observational results the use of US to guide vascular access has still not been adopted by many EP centers worldwide. 22 While the lack of convincing RCT data supporting US use discourages these to change their practice, others are reluctant to omit US in any patient even for the sake of performing such an RCT. 25 Our quasi-randomized analysis may serve as a substitute for a true RCT. We prospectively collected data on patients who underwent PVI during the same period, by the same operators, but were randomly assigned to US guidance based on its availability. The results demonstrate a remarkable improvement in the risk of vascular complications and serve as a basis for a more widespread adaptation of the technique of US-guided femoral access for AF ablation.

| Limitations
Our series is a single-center study, which could limit its generalizability to other centers. Although the study was randomized, it could not be blinded. The femoral vein punctures were performed by EP fellows in training with no relevant experience in US-guided vascular access. We did not collect data about puncture time and subclinical vascular complications as inadvertent femoral artery puncture. In addition, it cannot be ruled out that some of the complications occurred due to inadequate manual compression after sheath removal.

| CONCLUSION
Using US for femoral vein puncture in patients undergoing PVI decreased the rate of both major and minor vascular complications.
This quasi-randomized comparison strongly supports adapting routine use of US for AF ablation procedures.

ACKNOWLEDGMENTS
The authors have no funding to report.

DATA AVAILABILITY STATEMENT
The data sets presented in this article are not readily available because of Hungarian legal regulations. Requests to access the data sets should be directed to Peter Kupo, peter. kupo@gmail.com.