Ten-year Durability, Hemodynamic Performance, and Clinical Outcomes after Transcatheter Aortic Valve Implantation Using a Self-expanding Device

INTRODUCTION

The expansion of transcatheter aortic valve implantation (TAVI) to low-risk and younger patients has increased the relevance of the long-term durability of transcatheter heart valves (THV). The present study aims to assess the 10-year durability, hemodynamic performance, and clinical outcomes after TAVI using the CoreValve system.

METHODS

An analysis from a prospective registry with predefined clinical and echocardiographic follow-up included 302 patients who underwent TAVI with the CoreValve system between 2007 and 2015. Bioprosthetic valve failure (BVF) was defined as any bioprosthetic valve dysfunction-related death, re-intervention, or severe hemodynamic valve deterioration.

RESULTS

At the time of TAVI, the mean age was 80.41 ± 7.01 years, and the Society of Thoracic Surgeons (STS) score was 6.13 ± 5.23%. At latest follow-up (median [IQR]: 5 [2-7] years), cumulative all-cause mortality rates at 3, 5, 7, and 10 years was 23.7%, 40%, 65.8%, and 89.8%, respectively. Mean aortic valve area and transvalvular gradient post-TAVI and at 5, 7, and 10 years were 1.94, 1.87, 1.69, and 1.98 cm2 (p = 0.236) and 8.3, 9.0, 8.2, and 10.1 mmHg (p = 0.796), respectively. Overall, 11 patients had BVF, of whom six had structural valve deterioration (SVD). The 10-year actual and actuarial freedom from BVF was 96.1% and 78.8%, and from SVD was 97.9% and 80.9%, respectively. Three patients developed significant non-SVD due to severe paravalvular leakage, and two patients were diagnosed with infective endocarditis.

CONCLUSION

Using an early-generation self-expanding bioprosthesis, we documented durable hemodynamic performance and low rates of BVF and SVD up to 10 years after TAVI.

A Durable Porcine Pericardial Surgical Bioprosthetic Heart Valve: a Proof of Concept

Bioprosthetic leaflets made from animal tissues are used in the majority of surgical and transcatheter cardiac valve replacements. This study develops a new surgical bioprosthesis, using porcine pericardial leaflets. Porcine pericardium was obtained from genetically engineered pigs with a mutation in the GGTA-1 gene (GTKO) and fixed in 0.6% glutaraldehyde, and used to develop a new surgical valve design. The valves underwent in vitro hydrodynamic test in a pulse duplicator and high-cycled accelerated wear testing and were evaluated for acute haemodynamics and thrombogenicity in a juvenile sheep implant study for 48 h. The porcine surgical pericardial heart valves (pSPHVs) exhibited excellent hydrodynamics and reached 200 million cycles of in vitro durability, with no observable damage. Juvenile sheep implants demonstrated normal valve function with no acute thrombogenic response for either material. The pSPHV incorporates a minimalistic construction method using a tissue-to-tissue design to cover the stent. This new design is a proof of concept alternative to the use of bovine pericardium and synthetic fabric in surgical bioprosthetic heart valves.

Long term outcomes of transcatheter aortic valve implantation (TAVI): a systematic review of 5-year survival and beyond

BACKGROUND

Transcatheter aortic valve implantation/replacement (TAVI/TAVR) is becoming more frequently used to treat aortic stenosis (AS), with increasing push for the procedure in lower risk patients. Numerous randomized controlled trials have demonstrated that TAVI offers a suitable alternative to the current gold standard of surgical aortic valve replacement (SAVR) in terms of short-term outcomes. The present review evaluates long-term outcomes following TAVI procedures.

METHODS

Literature search using three electronic databases was performed up to June 2017. Studies which included 20 or more patients undergoing TAVI procedures, either as a stand-alone or concomitant procedure and with a follow-up of at least 5 years, were included in the present review. Literature search and data extraction were performed by two independent researchers. Digitized survival data were extracted from Kaplan-Meier curves in order to re-create the original patient data using an iterative algorithm and subsequently aggregated for analysis.

RESULTS

Thirty-one studies were included in the present analysis, with a total of 13,857 patients. Two studies were national registries, eight were multi-institutional collaborations and the remainder were institutional series. Overall, 45.7% of patients were male, with mean age of 81.5±7.0 years. Where reported, the mean Logistic EuroSCORE (LES) was 22.1±13.7 and the mean Society of Thoracic Surgeons (STS) score was 9.2±6.6. The pooled analysis found 30-day mortality, cerebrovascular accidents, acute kidney injury (AKI) and requirement for permanent pacemaker (PPM) implantation to be 8.4%, 2.8%, 14.4%, and 13.4%, respectively. Aggregated survival at 1-, 2-, 3-, 5- and 7-year were 83%, 75%, 65%, 48% and 28%, respectively.

CONCLUSIONS

The present systematic review identified acceptable long-term survival results for TAVI procedures in an elderly population. Extended follow-up is required to assess long-term outcomes following TAVI, particularly before its application is extended into wider population groups.

A correlation between long-term in vitro dynamic calcification and abnormal flow patterns past bioprosthetic heart valves

In this paper, a long-term in vitro dynamic calcification of three porcine aortic heart valves was investigated using a combined approach that involved accelerated wear testing of the valves in the rapid calcification solution, hydrodynamic assessment of the progressive change of effective orifice area (EOA) along with the transaortic pressure gradient, and quantitative visualization of the flow. The motivation for this study was developing a standardized, economical, and feasible in vitro testing methodology for bioprosthetic heart valve calcification, which would address both the hydrodynamic performance of the valves as well as the subsequent changes in the flow field. The results revealed the failure of the test valves at 40 million cycles mark, associated with the critical decrease in the EOA, followed by the increase in the maximum value of viscous shear stress of up to 52%, compared to the values measured at the beginning of the study. The decrease in the EOA was subsequently followed by the rapid increase in the maximum streamwise velocity of the central orifice jet up to the value of about 2.8 m/s, compared to the initial value of 2 m/s, and to the value of 2.2 m/s in the case of a control valve along with progressive narrowing of the velocity profile for two test valves. The significance of the current work is in demonstrating a correlation between calcification of the aortic valve and spatial as well as the temporal development of abnormal flow features.

Transcatheter heart valve crimping and the protecting effects of a polyester cuff

INTRODUCTION

Prior to deployment, the percutaneous heart valves must be crimped and loaded into sheaths of diameters that can be as low as 6mm for a 23mm diameter valve. However, as the valve leaflets are fragile, any damage caused during this crimping process may contribute to reducing its long-term durability in vivo.

MATERIAL AND METHOD

Bovine pericardium percutaneous valves were manufactured as follows. The leaflets were sutured on a nitinol frame. A polyester cuff fabric served as a buffer between the pericardium and the stent. Two valves were crimped and one valve was used as control. The valves were examined in gross observation and micro-CT scan and then the leaflets were processed for histology and analyzed in scanning electron microscopy, light microscopy and transmission electron microscopy.

RESULT

Crimping of the valves resulted in the increase thickness of the leaflets and there was no evidence of additional delamination. The heavy prints of the stents were irregularly distributed on the outflow surface in the crimped devices and were shallow and did not penetrate throughout the thickness of the leaflets. However, the wavy microscopy of collagen fiber bundles was well preserved. They were found to remain individualized without any agglutination as shown by the regular banding appearance.

CONCLUSION

Crimping of self-deployable valves per se caused only minor damages to the leaflets. However, the procedure could be refined in order to minimize areas of high pressure and swelling of the tissue that can be accompanied with flow surface disruption and increase of the hydraulic conductance. The incorporation of a polyester buffer serves to prevent the deleterious effects that may be caused if the pericardium tissue were in direct contact with the nitinol stent.

Degenerative changes and immune response after transcatheter aortic valve implantation. Comparison with surgical aortic valve replacement

BACKGROUND

Little is known about the valve degeneration process after transcutaneous aortic valve implantations (TAVI) that can have an important impact on patients' long-term prognosis.

AIM

To evaluate degenerative changes of TAVI using computed tomography (CT) compared to findings in patients that underwent surgical aortic valve replacement (SAVR). Subsequently, to compare the level of immune and inflammatory markers in both groups and test their possible role in the valve degeneration process.

METHODS AND RESULTS

49 patients after TAVI and 29 patients in the control group after SAVR underwent 2 years of follow-up and 8 patients from the TAVI group and 7 patients after SAVR underwent five years of follow-up. CT was performed in all patients and calcifications on prosthesis cusps in both groups were measured using Agatson calcium score. TAVI patients were older compared to patients who underwent SAVR [82 (62;86) vs. 74 (64;84) years, p<0.001], and had more comorbidities - higher EuroScore I [21.0 (5.0;46.0) vs. 6.15 (2.54;11.17), p<0.001]. TAVI patients had more often concomitant coronary artery disease (69.4% vs. 13.8%, p<0.001) and previous history of cardiac surgery (32.7% vs. 0.0%, p<0.001). Slight calcifications (mean Agatson score 50.76) on prosthetic cusps were found in 2 patients 4-5 years after TAVI and in 1 patient 2 years after SAVR (p=NS). Even though significant differences were found in values of tumor necrosis factor-α and E-selectin before, 1 year, and 2 years after implantation, no significant changes in values of inflammatory markers were observed during follow-up period in both groups of patients. Detailed analysis revealed no significant difference between values of inflammatory markers of patients with and without calcifications present on CT.

CONCLUSION

Minimal degenerative changes on TAVI prosthesis were observed in mid- and long-term follow-up. Systemic immune response did not differ between patients after TAVI and SAVR.