The Novel FlexNav Delivery System for Transcatheter Aortic Valve Implantation With the Portico Device: A Case Series

Background. Transcatheter aortic valve implantation (TAVI) is a safe and beneficial treatment for patients with severe symptomatic aortic stenosis at high and intermediate surgical risk. Success rates for TAVI continue to increase due to more refined procedural approaches and devices, and above all, to the improvements in procedural knowledge by TAVI operators. The development of a new delivery system represents an important evolutionary process in the TAVI procedure, both for the type of device and for the operators, as it may substantially expand indications, success rates, and safety. FlexNav (Abbott Cardiovascular) is a novel delivery system designed to improve ease and precision of TAVI using the Abbott Portico valve. Despite limited results on its advantages, such as those provided in the PORTICO investigational device exemption substudy, uncertainty persists on the actual role of FlexNav in real-world practice. Methods and Results. We hereby present our preliminary experience with FlexNav in a consecutive series of 18 patients undergoing TAVI with Portico valve in early 2020 (3 with axillary access). Procedural results were excellent, as shown by the absence of deaths, strokes, and major vascular complications (95% confidence interval, 0%-18.5%), and pacemaker implantation in 3 subjects (21.4%; 95% confidence interval, 4.7%-50.8%). Conclusions. Despite the small sample size, the present case series suggests that adoption of the FlexNav novel delivery system for TAVI with Portico valve is feasible and safe, and holds the promise of further improving early and long-term results of this procedure.

J INVASIVE CARDIOL 2021;33(6):E474-E478. Epub 2021 May 10.

Key words: aortic stenosis, delivery system, FlexNav, Portico valve, transcatheter aortic valve implantation

Transcatheter aortic valve implantation (TAVI), also called transcatheter aortic valve replacement (TAVR), is an appealing alternative to surgical aortic valve replacement (SAVR) for patients at intermediate to high surgical risk, and to medical therapy encompassing balloon aortic valvuloplasty for subjects at prohibitive surgical risk.^1,2 While several new-generation TAVI devices are available, and provide largely similarly favorable acute and long-term results,^3-6 refinements in devices and delivery systems are ongoing. Such improvements, together with the increased experience of operators and ancillary personnel, are key to the outstanding clinical results currently provided by TAVI, and suggest that even better outcomes may be expected in the future.⁷ Indeed, the basic difficulties encountered during TAVI represent the stimulus to the implementation of systems capable of limiting problems related to access, tension during the implant, damage to the aortic arch, and stability.^1,3-6

Yet, defining an easy-to-operate, effective, and safe delivery system remains challenging.¹ Notably, we can list as key criteria: (1) expansion of use in patients with smaller and or more complex accesses; (2) reduction of vascular complications and bleeding; (3) simplification of the implantation; and (4) greater implant precision, with reduction of paravalvular leak and need for pacemaker implantation. These criteria elucidate why improvements to delivery systems are critical for refining valve placement and positioning, with ensuing beneficial effects on adverse events and patient outcomes.⁸

The Portico valve (Abbott Cardiovascular) represents one of the leading self-expandable TAVI devices.⁹ Despite the lukewarm overall results of the Portico Resheathable Transcatheter Aortic Valve System U.S. Investigational Device Exemption (PORTICO IDE) trial,¹⁰ favorable data on Portico have been reported by several centers and studies, as well as in the PORTICO IDE substudy adopting the novel FlexNav delivery system (Abbott Cardiovascular).¹¹ Indeed, this delivery system, approved for clinical use in March 2020 in Europe, boasts small size (14-15 Fr equivalent), integrated sheath and hydrophilic coating, and controlled release features. FlexNav is a highly hydrophilic device, which allows it to overcome the difficulty of crossing thick skin, important calcifications of the femoral axis, or a calcified aortic arch — factors that often lead the first operator to lose the correct positioning of the rigid guide in the ventricle and increase the risk of bleeding complications. 

Building upon our experience with TAVI in general (>700 cases) and with Portico in particular (>300 cases), we retrospectively analyzed our experience with adoption of the FlexNav for TAVI with the Portico device.¹²

This is a retrospective analysis stemming from a prospective observational study that included TAVI cases performed at our institution since 2013.¹² Details on this study, including institutional review board and online registration, as well as specifics on our screening, periprocedural, procedural, and postprocedural management strategy, have been reported elsewhere in detail.^13,14

For the purpose of this work, we queried our administrative and study database (maintained in SQL) to retrieve baseline, procedural, and short-term outcomes on patients in whom TAVI was attempted using the Portico device with FlexNav delivery system. All procedures were performed by the same highly experienced operator (AG) and supported by another invasive cardiologist with extensive experience with structural heart disease (NC). Clinical outcomes were abstracted and tabulated as per established recommendations, using Valve Academic Research Consortium (VARC) guidelines.¹⁵

Descriptive statistical analysis was based on mean ± standard deviation for continuous variables, and count (%) for categorical variables. Inferential analysis was based on 95% confidence intervals (CIs), obtained from bootstrapping or exact binomial approaches, respectively. Computations were performed with Stata 13 (StataCorp) and Interactive Stats (https://statpages.info/confint.html).

A total of 18 patients underwent TAVI with the Portico device using the FlexNav delivery system at our institution in early 2020 (Table 1). All procedures were completed successfully, with axillary access utilized in 3 patients (17%). Notably, up to 30 days of follow-up, no death, stroke, major vascular complications, or major bleeding events occurred (95% CI, 0%-18.5%), whereas permanent pacemaker implantation was needed in 3 patients (17%; 95% CI, 3.6%-41.4%).

The landscape of structural heart disease is expanding momentously, with novel devices being introduced almost every month for mitral or tricuspid valve disease.¹⁶ In this setting, TAVI represents a pioneering intervention for valve disease. Despite being relatively young (at least in comparison with percutaneous coronary intervention), TAVI has already met many seminal milestones, such as toppling the role of medical therapy in patients with absolute contraindications to surgery and actively challenging SAVR in subjects at intermediate-to-high surgical risk.^1,2 Despite these successes, the activation and implementation of a TAVI program remains challenging, given the multidimensional challenges faced by invasive cardiologists as well as surgeons (Figures 1-3).¹⁷ A key factor to consider is the availability of several TAVI devices, each with its own strengths, weaknesses, and subtleties. Furthermore, device improvements are often provided, which may (hopefully favorably) shift the overall risk-benefit profile of the product.¹⁸

We hereby present our clinical experience with the novel FlexNav delivery system for Portico valve implantation in patients undergoing TAVI at our institution in early 2020.^10,11 This delivery system is characterized by small size, hydrophilic coating, and controlled release function, thus expanding the indications of TAVI with Portico, and increasing the safety and ease of the procedure. In our case series, we did not recognize any meaningful risk of suboptimal control due to a potential “slipperiness” of the overall system. Moreover, we found that the new delivery system did not intuitively influence the properties of the valve, but allowed a better, more precise delivery and enhanced the eventual procedural result. Furthermore, the new delivery system is easy to handle and offers a series of qualities useful for the operator. There is also greater stability and improved flexibility compared with the previous generation of the delivery system. Among the cases treated, 2 patients had a calcified and tortuous aortoiliac axis, such as to complicate the transition from the iliac tract to the abdominal aorta. In such patients, without the need to upgrade guidewire stiffness, it was possible to overcome the challenging anatomy through a counter-clockwise rotation, thanks to the hydrophilicity of the device. Similarly, in cases treated with transaxillary access, the device behaved favorably by gaining access without the introducer, and by maintaining stability during valve implantation.

While the sample described herein is limited, this series supports the results of the Portico IDE substudy, which reported no death or stroke among 100 patients (95% CI, 0%-3.6%), despite a major bleeding rate of 4.0% (95% CI, 1.1%-9.9%), major vascular complication rate of 7.0% (95% CI, 2.9%-13.9%), permanent pacemaker implantation rate of 21.4% (95% CI, 4.7%-50.8%), and moderate or severe paravalvular leak in 6.5% (95% CI, 2.9%-12.6%).^10,11,19 These results are particularly welcome, as the main analysis of the 381-patient PORTICO IDE trial, which compared Portico valve used in conjunction with an old-generation delivery system versus patients implanted with Sapien, Sapien XT, Sapien 3 (Edwards LifeSciences), CoreValve, Evolut-R, or Evolut-Pro valves (Medtronic), and showed Portico to be similarly effective, but less safe.¹⁰ In particular, higher rates of death, stroke, major bleeding, and major vascular complications were found for Portico, reaching statistical significance in some cases. 

In light of the PORTICO results and our own findings, unless further studies or reports highlight issues with FlexNav that have not yet been described, we suggest using it as the default delivery system for the Portico valve. The FlexNav system is capable of further improving the comparative risk-benefit profile of the Portico device, overcoming the weaknesses that potentially led to the overall PORTICO IDE study results.²⁰ Furthermore, we anticipate similar refinements in other TAVI devices, as progressive logical improvements are made to decrease the invasiveness and enhance the safety of the TAVI procedure. Such refinements will prove crucial to improve results, especially to further expand indications to TAVI in the ongoing quest to challenge the role of SAVR in subjects at intermediate or low operative risk.²¹

Study limitations. This work has several evident limitations, mainly due to the small sample size and single-center enrollment. In particular, we cannot exclude that our favorable results may depend, at least in part, on careful patient screening and selection. Moreover, endpoint adjudication and follow-up imaging were locally conducted and thus not validated externally in a blinded fashion.

Despite the small sample size, the present case series suggests that adoption of the FlexNav novel delivery system for TAVI with the Portico valve is feasible and safe, and holds the promise of further improving early and long-term results with this procedure.

From the ¹Unità Operativa di Interventistica Cardiovascolare, Pineta Grande Hospital, Castel Volturno, Italy; ²Unità Operativa di Emodinamica, Santa Lucia Hospital, San Giuseppe Vesuviano, Italy; ³Emodinamica Interventistica Casa di cura Villa Verde Taranto, Taranto, Italy; ⁴Division of Cardiology, Department of Emergency and Organ Transplantation, University of Bari, Bari, Italy; ⁵Department of Medico-Surgical Sciences and Biotechnologies, Sapienza University of Rome, Latina, Italy; and ⁶Mediterranea Cardiocentro, Napoli, Italy.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Biondo-Zoccai reports consulting fees for Cardionovum, Innovheart, Opens Medical, and Replycare. Dr Giordano reports financial interest in Abbott Medical. The authors report no conflicts of interest regarding the content herein.

Manuscript accepted September 15, 2020.

Address for correspondence: Dr Alberto Morello, Unità Operativa di Interventistica Cardiovascolare, Pineta Grande Hospital, Via Domitiana km 30.00, 81030 Castel Volturno, Italy. Email: albogottlieb83@gmail.com