​​A Case Series of Novel Technique of Coronary Protection for Patients With Low Coronary Height Undergoing Transcatheter Aortic Valve Implantation

Abstract

OBJECTIVE. Coronary artery occlusion (CAO) in patients undergoing transcatheter aortic valve implantation (TAVI) is rare but is associated with up to 50% mortality risk. We report a case series of a novel technique of coronary protection for patients undergoing TAVI at high risk of CAO. METHODS. Patients with symptomatic severe aortic stenosis scheduled for TAVI and at high risk of CAO were included. A noncompliant coronary angioplasty balloon was placed between the left coronary artery and the transcatheter heart valve. The distal “nose” of the balloon was positioned at the ostium of the left main and its main body “hanging” in the aorta. The coronary balloon was sized 1:1 to the left main, and simultaneous kissing balloon inflation was performed during valve deployment. RESULTS. Eight patients were included in this series. Five patients had previous isolated surgical bioprosthetic valves. The median left coronary height was 7.1 (6.0-8.4) mm with a median valve-to-coronary (VTC) distance of 3.3 (2.9-3.6) mm. There were no procedural complications, but one patient had a stroke during their in-hospital stay. After a median follow up of 12 (5.8-16.8) months, there were no mortality or rehospitalization events. CONCLUSION. Simultaneous kissing balloon is a novel technique of coronary protection in patients undergoing TAVI at high risk of CAO. Further studies are required to establish the safety of this novel technique.

Key words: TAVI, coronary artery occlusion, kissing balloon, case series

J INVASIVE CARDIOL 2023;35(9): Epub Aug 23

Introduction

Summary of clinical significance. Simultaneous kissing balloon is a novel technique of preventing coronary occlusion in patients undergoing transcatheter aortic valve implantation (TAVI) at high risk of coronary artery occlusion. It is a simple strategy to protect coronary arteries using a coronary angioplasty balloon with a short learning curve and the advantage of leaving no stent behind.

Overview. TAVI has become a standard treatment for patients with symptomatic severe aortic valve stenosis.¹ Advances in technology coupled with better operators’ experience have reduced procedural complications and improved safety outcomes. Nonetheless, certain anatomical features, such as low coronary height, remain a challenge when performing TAVI, and advanced planning is required to avoid obstructing coronary flow.

Coronary artery occlusion (CAO) in patients undergoing TAVI is not a common complication, with an incidence of <1% in the Transcatheter Valve Therapy Registry.² Nevertheless, this risk is more common in patients undergoing valve-in-valve with almost 4- to 6-fold increase when compared with TAVI in native valves.³ Additionally, CAO after TAVI is associated with a mortality risk of up to 50%.⁴

Two strategies are currently used for prevention of CAO: chimney stenting or BASILICA (Bioprosthetic or Native Aortic Scallop Intentional Laceration to Prevent Iatrogenic Coronary Artery Obstruction).^3,4 The former technique involves deployment of a coronary stent extending from the left main stem cranially and parallel to the transcatheter heart valve (THV).⁵ The BASILICA uses electrified guidewire to transverse the aortic leaflet, whether bioprosthetic or native, which can subsequently be lacerated in situ by the mid shaft of the electrified wire.⁶ Both techniques have important limitations, such as risk of stent thrombosis, restenosis, and challenging re-intervention impacting durability for chimney stenting; and limited availability for the BASILICA technique. More recently, the safety and feasibility of the first dedicated transcatheter leaflet-splitting device, ShortCut (Pi-Cardia), was reported.⁷ It requires a 16F sheath and employs a splitting element that is mechanically aligned and deployed against the degenerative leaflet from its ventricular side. Splitting is performed by retracting a distal unit supported by centralization while feeding on the guidewire.⁷

We report a novel and simple strategy for protecting coronary arteries using simultaneous kissing balloon (SKB) inflation during TAVI.

Methods

A series of selected patients scheduled for TAVI at the Freeman hospital between November 2020 and September 2022 who were considered at high risk of CAO were included in this study. All cases were discussed in a multidisciplinary Heart Team meeting.

Patients were eligible if they had one or more high-risk anatomical features of CAO. These included:

1. Low coronary artery height of <10 mm, as measured from the aortic annulus.

2. Shallow sinuses of Valsalva (SoV, average diameter <28 mm).

3. Narrow valve-to-coronary (VTC) distance of <4 mm for patients with previous isolated bioprosthetic surgical aortic valve replacement.^8-10

4. Length of the aortic leaflet more than coronary artery height.

The last criterion was met in one patient only with bicuspid aortic valve stenosis. A previous TAVI attempt was abandoned as concomitant aortogram during aortic balloon valvuloplasty demonstrated evidence of CAO. Two examples of computed tomography (CT) features related to patients undergoing SKB are presented in Figure 1.    

All TAVI procedures were performed as per standard clinical guidelines using SAPIEN 3 THV system (Edwards Lifesciences).

SKB inflation was performed by introducing a noncompliant coronary angioplasty balloon to the left coronary artery over a standard angioplasty wire (Figure 2). All cases were done via a standard 6F left coronary artery guide catheter. The sizing of the balloon was angiographically determined (1:1 to the left main, LM) following selective left coronary angiography. The coronary balloon was placed between the left coronary artery and the THV. The distal “nose” of the balloon was positioned at the ostium of the LM, and its main body remained “hanging” in the aorta (Figure 1). Importantly, the position of the coronary balloon was meticulously checked to minimize any endothelial injury to the left coronary system during inflation. A SKB inflation of the SAPIEN 3 and coronary balloon (inflated up to 12 atm pressure) was performed under rapid pacing via the left ventricular wire. The coronary protection balloon was deflated immediately after deflation of the THV balloon. Subsequently, the left coronary system was checked by angiography to rule out any complications.

Institutional Review Board approval was not sought as the reported procedure was considered a safer modification of an existing, accepted, and widely practiced procedure (chimney).

Statistical analysis. Data are presented as counts and percentage for categorical variables. For continuous variables, they are presented as mean (± standard deviation) for normally distributed data or median (Q1-Q3) for non-normally distributed data.   

Results

Eight patients were included in this series with mean age of 80 ± 5 years; 6 patients (75%) were women. The average body mass index was 32 ± 7 kg/m². Five patients had previous isolated surgical bioprosthetic valves. Four patients had a history of coronary artery disease and 3 underwent previous percutaneous coronary intervention (PCI). The mean Society of Thoracic Surgeons (STS) score was 5.8 ± 3.4.

The mean aortic valve peak gradient was 105 ± 22 mm Hg with an aortic valve area of 0.52 ± 0.13 cm². Five patients had normal left ventricular systolic function as assessed by periprocedural transthoracic echocardiography. Baseline patient characteristics are presented in Table 1.

The features on CT suggested high risk for CAO with a median left coronary height of 7.1 (6.0-8.4) mm and SoV diameter of 24.6 (22.8-29.2) mm. Patients with previous surgical aortic valve replacement had a median VTC distance of 3.3 (2.9-3.6) mm. The median right coronary height was 14.0 (12.5-16.3) mm. Individual patients’ CT characteristics are presented in Table 2.

The noncompliant balloon was sized 1:1 to LM with an average size of 5.2 ± 0.8 mm and length of 21 ± 3 mm. Seventy-five percent of patients underwent TAVI with 23 mm SAPIEN Ultra S3. No procedural complications were reported, but one patient had a stroke during in-hospital stay. All patients were discharged home the following day, except for one who underwent a stroke rehabilitation program. Antithrombotic regime included dual antiplatelet treatment for 1 month and, subsequently, a single antiplatelet for lifelong. In patients on oral anticoagulation, a single antiplatelet treatment was added for 1 month. Individual procedural characteristics, including antithrombotic regime and duration of follow-up, are presented in Table 3.

After a median follow-up of 12 (5.8-16.8) months, there were no reported mortality, myocardial infarction, target vessel revascularization, or rehospitalization events.

Discussion

This is the first case series reporting the safety outcomes of using the SKB technique in patients undergoing TAVI with high-risk features of CAO.

Certain anatomical features predispose patients to CAO, which include low coronary height (<12 mm) and narrow SoV (<30 mm).¹¹ Both features were present in our patients; nonetheless, no complications were reported during their procedure or at medium-term follow up using the SKB technique. The presence of a coronary balloon during TAVI deployment acts as a barrier to avoid obstructing the coronary ostia with deflection of crushed degenerated aortic valve leaflets away from the coronary ostia. Importantly, the coronary balloon was meticulously positioned so it did not cause any endothelial injury of the left coronary artery during balloon inflation. The distal marker of the coronary balloon was angiographically placed proximal to the ostium of the left main stem to avoid unnecessary balloon injury. It is important to highlight that positioning of the coronary balloon could be challenging and may be at risk of malpositioning when using this technique. Nonetheless, there are two important steps in this technique to reduce this risk. First, this technique is executed under rapid pacing to minimize any impact of cardiac output/ contractility on the position of the coronary balloon. The lack of meaningful blood pressure during inflation would help maintain the balloon position during TAVI. Second, the coronary balloon is inflated first, prior to the THV, to ensure its position is optimal prior to valve deployment. The radial force of the coronary balloon coupled with the rapid pacing would minimize the risk of balloon malposition during TAVI. Additionally, all patients post-procedure were commenced on additional antiplatelet treatment to reduce the thrombotic risk of any possible endothelial injury. Patients receiving oral anticoagulation were discharged on a combination of single antiplatelet (for 1 month) and oral anticoagulation. The use of optical coherent tomography would have obviated the need to adopt this strategy by ruling out any endothelial injury following use of the SKB technique.      

Previous reports highlighted the use of coronary angioplasty wire to prevent CAO.^12,13 Nonetheless, 4.3% of cases had definitive delayed CAO with significant mortality rate (3 out of 4 patients died).¹³ Therefore, the presence of coronary protection wire may not be enough to prevent the risk of delayed CAO. In our case series, there were no cases of delayed CAO.

Other techniques have been used, such as the chimney stenting. Notably, the long-term outcomes of this technique related to the risk of stent failure is unclear. Factors such as turbulent flow, unopposed stent to the coronary wall, duration of the antiplatelet, and future coronary access need to be considered when using this technique. Additionally, the use of upfront stenting may be prone to failure due to the severe calcification of the aortic valve leaflets. When positioned between the THV and the aorta, implanted new generation stents may not have enough radial force to withstand extrinsic compression, particularly with their current thin-struts feature. On the other hand, a fully inflated coronary angioplasty balloon (at 12 atm) would provide sufficient radial force to withstand and deflect the degenerative aortic valve leaflets away from the ostium of the left coronary artery as highlighted in our case series.

The use of chimney stenting as a bailout strategy for established CAO was associated with significant procedural events (>50%).⁵ The SKB technique to mitigate the risk of CAO during TAVI could be perceived as a modified chimney technique; however, it has the advantage of leaving no stent behind. If the crushed leaflet recoiled to precipitate CAO, a guide extension GuideLiner catheter (Teleflex) could be introduced over the balloon, and a full chimney technique is executed. It is important to highlight that we observed no failure of the SKB technique requiring stent implantation in our series.

The BASILICA is considered an alternative strategy to prevent CAO. However, this technique is a highly specialized tool and not widely available in all centers. Additionally,  it may not be feasible to be performed in heavily calcified leaflets.¹⁴ In contrast, SKB could be performed at any center using a standard angioplasty wire and coronary balloon.

This study is limited by the relatively small sample size of 8 cases. A larger cohort is needed to better evaluate the efficacy and safety of the SKB technique. Moreover, this technique was exclusively used in patients undergoing TAVI with a balloon-expandable valve and was not assessed in patients undergoing TAVI with a self-expanding valve. The latter was associated with increased risk of delayed CAO when compared to balloon-expandable ones.¹² The continuous expansion of the nitinol frame after withdrawing the coronary balloon may subject patients to unpredicted risk and may result in delayed CAO. Therefore, the safety of this novel technique is currently limited to the use of balloon-expandable valves. Additionally, the SKB technique has not been tested in patients with severe left ventricle (LV) impairment. Although 3 out of 8 patients had impaired LV function, none had an ejection fraction less than 30%. However, as the coronary balloon is inflated during rapid ventricular pacing, the effect of inflation on reducing coronary blood flow would not be expected to be clinically significant. Although all included patients underwent selective coronary angiography post procedure, we did not obtain CT post TAVI. This would have added further insights into the SKB technique, may have confirmed the location of the deflected degenerative aortic valve leaflets away from the coronary ostia, and would have identified those patients who were at true risk of coronary obstruction by measuring VTC post TAVI.     

Conclusion

In conclusion, SKB is a novel technique to manage patients undergoing TAVI at high risk of CAO. Further studies are required to establish the safety of this novel technique.

Affiliations and Disclosures

From the ¹Cardiothroacic Centre, Freeman Hospital, Newcastle upon Tyne, UK; ²Translational and Clinical Research Institute, Newcastle University, Newcastle, UK

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

Corresponding author: Mohammad Alkhalil, Cardiothoracic Centre, Freeman Hospital, Newcastle-upon-Tyne NE7 7DN, United Kingdom. Email: mak-83@hotmail.com, Mohammad.alkhalil@nhs.net

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