TAVI in the Case of Preexisting Mitral Prosthesis: Tips & Tricks and Literature Review

Abstract: Very limited data exist on transcatheter aortic valve implantation (TAVI) in the setting of a preexisting mitral prosthesis regarding the technique, potential complications, and outcomes. Here, we report two cases of transfemoral TAVI with a self-expanding bioprosthesis (CoreValve; Medtronic, Inc) in patients who had previously undergone mitral valve replacement (one with an Omniscience and one with a St. Jude prosthesis). A brief literature review is also presented. 

J INVASIVE CARDIOL 2014;26(11):609-613

Key words: TAVI, TAVR, PAVI, PAVR, aortic stenosis, mitral prosthesis

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The European Society of Cardiology guidelines have recently designated transcatheter aortic valve implantation (TAVI) for the management of symptomatic severe aortic stenosis (AS) as a class I indication for patients not suitable for the gold-standard open surgery and a class IIa for patients in whom the heart-team reaches such a consensus.¹ However, very limited data exist on TAVI in the setting of a preexisting mitral prosthesis regarding the technique, potential complications, and outcomes. We present two cases of transfemoral TAVI with a self-expanding bioprosthesis (CoreValve; Medtronic, Inc) in patients who had previously undergone mitral valve replacement: one with an Omniscience and one with a St. Jude prosthesis. We also offer a brief literature review. 

Case Reports

Patient #1. Routine procedural details have previously been described in detail.^2,3 The first patient was a 66-year-old female with a medical history of rheumatoid arthritis and mitral valve replacement with an Omniscience prosthesis for mitral valve stenosis due to rheumatic fever, implantation of permanent pacemaker for sick sinus syndrome, hypothyroidism, arterial hypertension, dyslipidemia, pneumonic fibrosis, and chronic obstructive pulmonary disease (forced expiratory volume at 1 second was 1 L/s). The patient had severe AS and was symptomatic at minimal activity (New York Heart Association [NYHA] functional class III). Baseline echocardiographic data included aortic valve area of 0.60 cm², mean aortic valve (AV) gradient of 42 mm Hg, peak AV gradient of 64 mm Hg, left ventricular ejection fraction (LVEF) of 55%, mitral valve mean gradient of 3 mm Hg, and pulmonary artery systolic pressure (PASP) of <35 mm Hg. Logistic EuroSCORE was calculated to be 13.1%. Due to the aforementioned comorbidities, the heart team at our hospital decided to recommend TAVI as the best treatment option for the patient.

Preprocedural screening with multislice computed tomography (MSCT) was conducted not only for a thorough evaluation of the access site, but also in order to assess and estimate the distance between the aortic annulus and the mitral prosthesis metallic frame (mitroaortic space), which was measured to be 5.8 mm (Figures 1I and 1II). Aortic annulus perimeter was 7.61 cm and area was 3.854 cm². The procedure was conducted under local anesthesia and mild sedation. The radiopaque frame of the mitral prosthesis was utilized as a landmark to estimate the mitroaortic space and to guide implantation. Aortic valve balloon predilatation with a 22 x 40 mm balloon was performed at a relatively slow ventricular rate (~160 beats/min) in order to maintain flow through the mitral valve. Care was taken for the balloon to be sufficiently into the left ventricle outflow in order to uncover any interference with the prosthetic mitral leaflets. Indeed, unobstructed mitral movement was confirmed. Of note, movement of the mitral leaflets during balloon inflation may provide an indication of aortic bioprosthesis functionality in the case of a deep implantation and make the interventionalist aware of its potential consequences. However, utilization of intraoperative transesophageal echocardiography (TEE) during or  immediately after TAVI will verify any potential malfunctioning and therefore both techniques should be used. In our center, TEE is not routinely used intraprocedurally; therefore, it was not an option and we had to rely on fluoroscopic images only. Moreover, transthoracic echocardiography was available in the catheterization laboratory suite and was used to verify aortic and mitral valve functionality. TAVI was successfully conducted utilizing a 26 mm CoreValve prosthesis  and the patient was discharged at day 7. At 1-month follow-up, mean AV gradient was 5  mm Hg, peak AV gradient was 7 mm Hg, grade I aortic regurgitation was observed, LVEF was 55%, PASP was <35 mm Hg, mitral valve functionality was free of any signs of regurgitation or stenosis, and the patient was assessed to be in NYHA class I.

Patient #2. The second patient was an 85-year-old female who was referred to our department with a diagnosis of severe symptomatic AS for further evaluation and treatment. She was symptomatic at mild activity (NYHA functional class III). Her medical history included coronary artery bypass grafting and mitral valve stenosis treated with mitral valve replacement with a St. Jude prosthesis 10 years ago, arterial hypertension, non-insulin dependent diabetes mellitus, chronic kidney disease, and pulmonary hypertension. Baseline echocardiogram revealed an aortic valve area of 0.88 cm², mean AV gradient of 51 mm Hg, peak AV gradient of 86 mm Hg, LVEF of 45%, mitral valve mean gradient of 4 mm Hg, and PASP of 65 mm Hg. Logistic EuroSCORE was calculated to be 51.8%. 

Prior to bioprosthesis implantation, minimum aortic annulus to mitral valve distance (mitroaortic space) was estimated to be 9.3 mm by angioscopy utilizing a metric pigtail catheter (Figure 1A). The radiopaque leaflets of the mitral prosthesis were considered as landmarks both for the preprocedural measurement of the mitroaortic space and during TAVI (Figure 1B). A 29 mm CoreValve aortic bioprosthesis was successfully implanted (Figure 1C). Balloon predilation of the native aortic valve with a 25 x 40 mm balloon (Nucleus; Numed) was performed at a rate of 160 beats/min. The patient was discharged at day 9 post intervention with improvement of her symptoms. At 1-year follow-up, mean AV gradient was 4 mm Hg, peak AV gradient was 6 mm Hg, grade of aortic regurgitation was unchanged (I/IV), LVEF was 55%, PASP was <35 mm Hg, mitral valve functionality was free of any signs of regurgitation or stenosis, and the patient was assessed to be in NYHA class II. 

Discussion

Shortly after the advent of TAVI, interventionalists sought to explore off-label uses for patients without alternative treatment options. AS with preexisting mitral prosthesis is such an application. In fact, this has been an exclusion criterion in the Placement of Aortic Transcatheter Valve (PARTNER) trial.⁴ To the best of our knowledge, only 14 cases of transfemoral TAVI have been reported in patients with a prior mechanical mitral valve prosthesis. The CoreValve prosthesis was implanted in 8 cases (first report by Brushi et al in 2009⁵) and the Sapien prosthesis (Edwards Lifesciences) was implanted in 6 cases (first report by Dumonteil et al⁶). In addition, a total of 27 cases have been conducted via transapical approach (first report by Rodés-Cabau et al in 2008⁷) (Table 1). 

There are several issues to consider when TAVI is performed in the setting of a preexisting mitral prosthesis:^6-8 (1) the measurement of the mitroaortic space; (2) the potential of fully expanding the aortic bioprosthesis without any deformation or distortion of the frame or the valve housing; (3) device embolization due to “watermelon seeding” effect; (4) interference with the prosthetic mitral leaflets or mitral prosthesis deformation affecting functionality; and (5)choice of vascular access. 

Therefore, special care should be paid in preprocedural screening of the patient and particularly in the evaluation of mitroaortic space, while prosthesis oversizing should be avoided. A distance of 4 mm should be required in order to permit secure deployment of the inflow part of the Core-Valve frame without interfering with the function of the mitral prosthesis leaflets. Alternatively, an Edwards Sapien valve could also be used in such patients. One should mention that the advantage of the CoreValve prosthesis is the gradual deployment process, which permits fine adjustments on implantation depth and avoidance of interference with the preexisting mitral prosthesis. Even in cases where the bioprosthesis extends too deep, withdrawal of the valve into the ascending aorta (before total release) or bail-out repositioning techniques (after release) may be an option.^9-11 On the contrary, if mitroaortic distance is less than 4 mm, the Edwards Sapien prosthesis is the only appropriate selection since this aortic prosthesis is to be aligned with the aortic valve annulus, therefore limiting the chances of interference with the preexisting mitral prosthesis. As far as mitroaortic space estimation is considered, angiography with metric pigtail or with sizing balloon, three-dimensional TEE, and MSCT have been employed to measure mitroaortic distance.^12,13 Interestingly, while MSCT is the most accurate technique, it has been utilized in fewer than half of the reported cases (Table 1). 

In addition, the type of the preexisting mitral prosthesis may play an important role in the possibility of interference with the aortic bioprosthesis. Low-profile, high-flow mechanical mitral prostheses protrube less into the left ventricle in comparison with the longer struts of mitral bioprostheses.¹⁴ Indeed, this may be more important in cases of CoreValve implantation, where a portion of the valve frame will extend into the left ventricular outflow tract. 

Moreover, intraprocedural observation of mitral prosthesis during balloon predilatation of the AV has been suggested¹⁵ as a means of assessment of feasibility right before aortic bioprosthesis implantation. Indeed, this technique may be utilized as an indirect confirmation to proceed with TAVI. However, the maintenance of even low perfusion during rapid ventricular pacing is of importance, otherwise mitral leaflet observation may be futile. Therefore, lesser pacing rates should be intentionally used. A second point to consider intraprocedurally is to perform meticulous manipulations during valve deployment and to use the radiopaque components of the mitral prosthesis as landmarks.

As far as the choice of vascular access is concerned, comprehensive preprocedural screening, as routinely performed in centers performing TAVI,² should always be followed. In our experience, TAVI in the case of preexisting mitral prosthesis has been conducted uneventfully utilizing transfemoral access in both patients. However, it should be noted that in the available literature, most of such experience is derived from cases performed with transapical access (Table 1). Undoubtedly, as Soon et al have suggested,¹⁶ transapical approach has several advantages to the transfemoral approach in such patients. It allows the interventionalist to have more efficient prosthesis maneuvers due to the shorter access-site balloon distance and coaxial alignment.¹⁶ To the best of our knowledge, no published cases of such procedures through the subclavian access exist. Finally, direct aortic access (either with mini-sternotomy or parasternal approach through the second intercostal space) could also be used, as reported by Bruschi et al⁸ (Table 1). However, certain anatomical features such as the angle of the aortic annulus to the horizontal plane, the course of the ascending aorta, and the presence of enough distance to accommodate the valve (in the case of the CoreValve prosthesis) should be taken into account.

Finally, surgical data suggest that in patients undergoing aortic valve replacement, the requirement for permanent pacemaker implantation is increased if mitral valve operation has preceeded.¹⁷ Similarly, after TAVI, mechanical forces, edema, or ischemia exerted at the fibrous skeleton of the aortic valve, considering the immediate anatomical vicinity of the AV node and the proximal conduction bundle, may precipitate for significant conduction abnormalities requiring permanent pacemaker implantation.

In conclusion, TAVI in patients with preexisting mitral prosthesis is feasible, but prospective long-term follow-up data are needed.

References

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From the 1st Department of Cardiology, Hippokration Hospital, Medical School, National & Kapodistrian University of Athens, Greece.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Vavuranakis is a proctor for CoreValve (Medtronic, Inc). Ms Kariori reports a grant from the State Scholarship Foundation. No other authors report any conflicts of interest regarding the content herein.

Manuscript submitted December 19, 2013, provisional acceptance given January 20, 2014, final version accepted February 25, 2014.

Address for correspondence: Manolis Vavuranakis, Associate Professor, 13 Astypaleas, Anoixi, Attiki-14569, Greece. Email: vavouran@otenet.gr and dvrachatis@gmail.com