Transfemoral vascular access in electrophysiology: should we exclusively rely on ultrasound guidance?

This editorial refers to ‘Value of ultrasound for access guidance and detection of subclinical vascular complications in the setting of atrial fibrillation cryoballoon ablation’ by E. Ströker et al., on pages 434--439. Atrial fibrillation (AF) ablation procedures start and end with vascular access. They require the insertion of several catheters via a femoral vascular access for treatment (and monitoring) purposes. It is annoying for both the investigator and the patient if the perfect ablation result is confounded by an access-site related complication. Depending on the type of vascular complications this can affect patients’ recovery, lengthen the hospital stay and cause further resource-consuming and painful treatment and in the worst case increase mortality. The risk of life-threatening complications with long-term sequelae (peri-procedural death, oesophageal injury, peri-procedural stroke) after AF ablation are rare with an incidence each of less than 1%.1 Inguinal vascular complications (IVC) instead are mostly reported in a range between 2% and 4%,1 but outliers with up to 10%2 can also be found. This remarkable variation between the trials might be explained by a variable quality of care among different treatment centres but also questions the validity and reporting of data: first, there are major differences in the definition and grading of IVC: some studies merge these complications and name them very unspecifically ‘vascular complications’ or groin haematoma. Additional specifications such as pseudoaneurysm, arterio-venous-fistula, retroperitoneal haematoma, and local infections are sometimes missing. Second, the reported rates are mostly based on clinical judgement during the hospital stay, thorough ultrasound (US) controls were not performed. Third, in most trials late complications were not collected. Fourth, the exact mode of vascular access (how many sheaths of which sizes, arterial femoral line used) and post-procedural compression management remain often unclear. Fifth, over the last years recommendations for the peri-interventional anticoagulation has changed from interrupted vitamin K antagonist (VKA) therapy bridged with heparin to uninterrupted VKA or non-vitamin K antagonist oral anticoagulant (NOAC) therapy. Traditional approaches such as anatomical landmarks, fluoroscopic guidance, and micropuncture access have been used for years and many interventionalists feel ‘safe’ with this method. However, a growing number of studies in radiofrequency AF ablation have shown that there is still scope for improvement when switching from the traditional access methods to using US guidance instead.3 Utrasound allows direct visualization of target and non-target vessels and should allow a more accurate sticks, even though it does not diminish ‘high sticks’.4 In this issue of EP-Europace, Ströker et al.5 present the data of 1435 consecutive patients undergoing AF ablation in two centres with second generation cryoballoon technology between 2012 and 2017. They used a minimalistic catheter setting. Two venous sheaths, one of it relatively large (15 Fr and 6 Fr) were placed. According to their vascular access policy during different timeframes (June 2012–September 2015, September 2015–August 2016, August 2016–July 2017) they divided the study population into three groups: conventional venipuncture without US guidance and clinical outcome evaluation (US−/−), conventional vascular access with systematic post-procedural US of the access site US−/+), and standardized use of US for venipuncture and evaluation of access 1 day after the procedure (US+/+ group). The patients in the last two groups received a routine post-operative access check with ultrasonography to receive objective outcome data whereas the US−/− group was controlled on a clinical basis. Within the US−/− group, one-third of IVC were recognized after discharge. Subclinical IVC could have missed but their clinical relevance seems to be low. However, vice versa, objective parameters might not always reflect the clinical impact. While major clinical events were seen in 1.1%, major/minor US events were described more often (in 3.8%/7.5%) in the US−/+ group. Of major US events, there were three already thrombosed pseudoaneurysms. Nevertheless, US guidance for venipuncture showed a significant decrease in IVC with near-to-zero major clinical IVCs. Multivariate analysis revealed only the use of US guidance as a predictor to avoid major US event, but not the mode of anticoagulation (NOAC vs. VKA), age, sex, body mass index, or operator training status. Interestingly, the time from beginning the femoral puncture to transseptal puncture decreased from 14.8 ± 7 min to 13.4 ± 7 min even though a higher proportion of trainees in the US+/+ group was reported. US-guidance seems to be efficient. The technique seems to have a fast learning curve, making it attractive to beginners. The results by Ströker et al.5 are in line with a meta-analysis by Sobolev et al.3 where a total of 4064 subjects from four observational trials on radiofrequency AF ablation were included.3 US guided femoral vein cannulation was associated with a 60% reduction in major vascular access complications (relative risk 0.40, 95% confidence interval 0.28–0.91) and a 66% reduction in minor vascular complications (relative risk 0.34, 95% confidence interval 0.15–0.78). The number needed to treat (NNT) to prevent a single major IVC by using US for vascular access was 100 in the meta-analysis, whereas Ströker et al.5 reported an NNT of only 29 patients to prevent one major US event. Data for femoral arterial puncture under US guidance is promising and similarly effective in a meta-analysis including 1422 subjects from four randomized trials.6 However, it should be acknowledged that this result is mainly based on 1004 patients from one trial,4 whereas the other three trials did not reach statistical significance.7–9 The existing studies in electrophysiology are observational trials that have reported only complication rates for a single time point before and after the introduction of US rather than multiple data points over a period of time. There is a high potential for bias and confounders as they did not investigate secular trends. It might be that the observed IVC rate in the conventional groups led to a higher awareness of IVC and that the intra-procedural management for inadvertent arterial puncture and post-procedural compression have changed to minimize IVC risks, and therefore, influenced the results as a confounder. There is a lack of observational trials with high internal validity or randomized multicentre trials. Interrupted time series might be the better option for further observational analyses, which can evaluate level changes and secular trends. Alternatively, randomized trials should be conducted. Additionally, there is a clear need to collect and report data on puncture attempts, intra- and post-procedural compression times and modes as these critical steps can influence the occurrence and course of IVC. Even though IVC are usually relatively benign and self-limiting we should minimize the overall risks to our patients undergoing AF ablation. The first step is to monitor complications thoroughly,10 and if needed to critically review the whole process. For vascular access the main questions are: how many sheaths are really necessary? How can the cannulation technique be improved? Can we optimize the post-procedural vascular closure/compression technique? Since every single access method has its pitfalls, interventionalists should use a skill set mix of anatomical landmarks, fluoroscopic guidance and US to minimize the risk of IVC and to benefit the patients. Minimizing IVC can save a lot of money to the healthcare system11 and on the other hand, reduce the discomfort for patients. Future studies with high internal and external validity are needed to evaluate its (cost-) effectiveness and efficacy. Conflict of interest: none declared.