Safety, efficacy, and hemodynamic performance of a stented bovine pericardial aortic valve bioprosthesis: Two-year analysis

Recent Advances in the Modification and Improvement of Bioprosthetic Heart Valves

Valvular heart disease (VHD) has become a burden and a growing public health problem in humans, causing significant morbidity and mortality worldwide. An increasing number of patients with severe VHD need to undergo heart valve replacement surgery, and artificial heart valves are in high demand. However, allogeneic valves from donors are lacking and cannot meet clinical practice needs. A mechanical heart valve can activate the coagulation pathway after contact with blood after implantation in the cardiovascular system, leading to thrombosis. Therefore, bioprosthetic heart valves (BHVs) are still a promising way to solve this problem. However, there are still challenges in the use of BHVs. For example, their longevity is still unsatisfactory due to the defects, such as thrombosis, structural valve degeneration, calcification, insufficient re-endothelialization, and the inflammatory response. Therefore, strategies and methods are needed to effectively improve the biocompatibility and longevity of BHVs. This review describes the recent research advances in BHVs and strategies to improve their biocompatibility and longevity.

Hemodynamic Comparison between the Avalus and the Perimount Magna Ease Aortic Bioprosthesis up to 5 Years

BACKGROUND

 We aimed to compare hemodynamic performance of the Avalus (Medtronic) and the Perimount Magna Ease (PME, Edwards Lifesciences) bioprosthesis up to 5 years by serial echocardiographic examinations.

METHODS

 In patients undergoing aortic valve replacement, 58 received PME prostheses between October 2007 and October 2008, and another 60 received Avalus prostheses between October 2014 and November 2015. To ensure similar baseline characteristics, we performed a propensity score matching based on left ventricular ejection fraction, age, body surface area, and aortic annulus diameter measured by intraoperative transesophageal echocardiography. Thereafter, 48 patients remained in each group. Mean age at operation was 67 ± 6 years and mean EuroSCORE-II was 1.7 ± 1.1. Both values did not differ significantly between the two groups.

RESULTS

 At 1 year the mean pressure gradient (MPG) was 15.4 ± 4.3 mm Hg in the PME group and 14.7 ± 5.1 mm Hg in the Avalus group (p = 0.32). The effective orifice area (EOA) was 1.65 ± 0.45 cm2 in the PME group and 1.62 ± 0.45 cm2 in the Avalus group (p = 0.79). At 5 years the MPG was 16.6 ± 5.1 mm Hg in the PME group and 14.7 ± 7.1 mm Hg in the Avalus group (p = 0.20). The EOA was 1.60 ± 0.49 cm2 in the PME group and 1.51 ± 0.40 cm2 in the Avalus group (p = 0.38). Five-year survival was 88% in the PME group and 91% in the Avalus group (p = 0.5). In the PME group, there were no reoperations on the aortic valve, whereas in the Avalus group three patients required a reoperation due to endocarditis.

CONCLUSION

 Both bioprostheses exhibit similar hemodynamic performance during a 5-year follow-up.

A Controlled Trial Comparing One-Year Hemodynamics of Two Bovine Pericardial Valves

BACKGROUND

 This randomized controlled trial was designed to compare 1-year hemodynamic performances and clinical outcomes after aortic valve replacement (AVR) using a recently introduced (the AVALUS group) and worldwide used (the CEPME group) bovine pericardial bioprostheses.

METHODS

 Patients were screened to enroll 70 patients in each group based on a noninferiority design. The primary endpoint of the trial was the mean pressure gradient across the aortic valve (AVMPG) at 1 year after surgery. One-year echocardiographic data were obtained from 92.1% (129 of 140 patients) of the study patients.

RESULTS

 There were no differences in baseline characteristics, including sex and body surface area (1.64 ± 0.18 vs. 1.65 ± 0.15 m2) between the groups. The AVMPG on 1-year echocardiography was 14.0 ± 4.3 and 13.9 ± 5.1 mmHg in the AVALUS and CEPME groups, respectively (the p-value for noninferiority was 0.0004). In the subgroup analyses for the respective size of the prostheses, AVMPG of the 19-mm prostheses was significantly lower in the AVALUS group than in the CEPME group (14.0 ± 4.3 vs. 20.0 ± 4.7 mmHg, p = 0.012), whereas those of the other sizes were not significantly different between the two groups. There were no significant differences in the effective orifice area (1.49 ± 0.40 vs. 1.53 ± 0.38 cm2, p = 0.500) or effective orifice area index (0.91 ± 0.22 vs 0.93 ± 0.23 cm2/m2, p = 0.570) in all the patients, or in the subgroup analysis for the 19-mm prosthesis. There were no differences in the 1-year clinical outcomes between the two groups.

CONCLUSION

 The 1-year hemodynamic and clinical outcomes of the AVALUS group were noninferior to those of the CEPME group (NCT03796442).

Preliminary Report from a Randomized Controlled Trial Comparing Two Bovine Pericardial Valves

BACKGROUND

A randomized controlled trial was designed to compare 1-year hemodynamic profiles and clinical outcomes after bioprosthetic aortic valve replacement (AVR) using a recently introduced (study group) and world-widely used (control group) bovine pericardial bioprostheses. This study evaluated early postoperative outcomes as a preliminary analysis.

METHODS

The primary end point of the trial was the mean pressure gradient across the aortic valve (AVMPG) at 1 year after surgery. Patients were screened to enroll 70 patients in each group based on a noninferiority design. Early postoperative hemodynamic and clinical outcomes were compared between the two groups.

RESULTS

There were no differences in baseline characteristics, including sex and body surface area (1.64 ± 0.18 vs. 1.65 ± 0.15 m2) between the two groups. The AVMPG on early postoperative echocardiography was 15.2 ± 4.6 mm Hg and 16.5 ± 6.2 mm Hg in the study and control groups, respectively (p = 0.177). Although AVMPG of the 19 mm prostheses was lower in the study group than in the control group (17.0 ± 6.3 mm Hg vs. 22.8 ± 6.6 mm Hg, p = 0.039), there were no significant differences in the effective orifice area in all patients (1.57 ± 0.41 cm2 vs. 1.53 ± 0.34 cm2, p = 0.568), and each valve size. The effective orifice area index was also similar between the two groups in overall (p = 0.352), and in each valve size. There were no significant differences in clinical outcomes including operative mortality and postoperative complications between the two groups.

CONCLUSION

Early postoperative hemodynamic and clinical results after AVR using a recently introduced bovine pericardial valve were comparable with those using the control valve (NCT03796442).

Surgical aortic valve replacement with a stented pericardial bioprosthesis: 5-year outcomes

OBJECTIVES

This analysis evaluated the safety, durability, and haemodynamic performance of a stented bovine pericardial valve through 5 years of follow-up in patients with an indication for surgical aortic valve replacement (SAVR).

METHODS

Kaplan-Meier analysis was used to estimate the incidence of survival and valve-related thromboembolism, major paravalvular leak (PVL), endocarditis, structural valve deterioration (SVD), and reintervention. Mean aortic gradient and New York Heart Association (NYHA) class were also evaluated.

RESULTS

1118 patients have received the Avalus valve (Medtronic); 564 have completed 5-year follow-up. Median follow-up was 4.85 years (4810 patient-years total follow-up). At baseline, mean age was 70.2 ± 9.0 years; 75.1% of patients were male. STS predicted risk of mortality was 2.0 ± 1.4%. Most patients were in NYHA class II (46.8%) or III (40.3%). At 5 years follow-up, the overall Kaplan-Meier survival rate was 88.1% (85.9-90.0%). The Kaplan-Meier event rates were 5.6% (4.3-7.2%) for thromboembolism, 4.4% (3.2-6.0%) for endocarditis, 0.2% (0.0-0.7%) for major PVL, and 3.2% (2.3-4.6%) for reintervention. There were no cases of SVD. Mean gradient decreased from 42.1 ± 17.1 mmHg at baseline, to 13.1 ± 4.7 mmHg at discharge, and remained stable at 12.5 ± 4.6 mmHg at 5 years. More than 95% of patients were in NYHA class I/II 5 years after surgery.

CONCLUSIONS

The findings of a high survival rate, excellent safety, no SVD, and stable haemodynamic performance and functional status through 5 years of follow-up are encouraging. Additional follow-up is needed to assess the long-term durability of this contemporary surgical bioprosthesis.

Stress exercise haemodynamic performance and opening reserve of a stented bovine pericardial aortic valve bioprosthesis

OBJECTIVES

Despite unusual high rates of patient-prosthesis mismatch (PPM), excellent midterm clinical outcomes have been reported after surgical aortic valve replacement (SAVR) with the Avalus™ bioprosthetic valve (Medtronic). To elucidate this "PPM conundrum," the Avalus valve haemodynamics were assessed during exercise testing.

METHODS

Of the 148 patients who had undergone SAVR with the Avalus valve at our institution, 30 were randomly selected among those in whom stress test was deemed feasible and underwent a resting transthoracic echocardiography immediately followed by exercise echocardiography. Severe PPM was defined as indexed effective orifice area (iEOA) ≤ 0.65 cm² /m² and moderate PPM as iEOA > 0.65 and ≤ 0.85 cm² /m² . Measured PPM was determined with the use of the measured iEOA at rest or stress, while the estimated PPM was based on the estimated iEOA, derived from the mean EOA reported for each valve size in the manufacturer chart.

RESULTS

Measured EOA significantly increased from rest to peak exercise in all PPM groups (p < .05) and the rates of moderate and severe measured PPM decreased from 40% and 20% to 27% and 0%, respectively. The patients with low-flow state (flow < 250 ml/s) had significantly lower measured rest EOA (p = .03). On the basis of the estimated iEOA, there was no severe PPM and 19 patients had moderate PPM (63.3%), with a significantly lower opening reserve than the patients without estimated PPM (p = .04). The estimated iEOA was more reliably correlated to the measured iEOA at maximal stress than the measured iEOA at rest, especially in patients with a low-flow state.

CONCLUSIONS

This study supports the concept of an opening reserve of the Avalus valve to explain the PPM conundrum and promotes the use of exercise Doppler-echocardiography to complete the assessment of mismatch, especially in patients with a low-flow state. Published estimated EOA seems reliable to predict the haemodynamic performance of the Avalus valve, whether the flow conditions at rest.

Commentary: Another layer to the "PPM conundrum"

How do manufacturer estimates of valve performance match up to reality and stress testing? We are reviewing a manuscript by Porterie et al. in the Journal of Cardiac Surgery detailing a single-center, assessment of Avalus™ bioprosthetic valve hemodynamics during stress echocardiography. At maximal stress, they found that indexed effective orifice area had better alignment with manufacturer estimates than measurements at rest. In addition, they found a significant difference between EOA and flow rates at rest versus maximal exertion and quantified it as the "opening reserve." Patients without patient prosthetic mismatch had much higher opening reserves. This interesting study helps us to understand how estimates align with reality and draws attention to the concept of the opening reserve. Could differences in opening flow impact the durability or longevity of prosthetics?

Surgical pericardial heart valves: 50 Years of evolution

Valve disease carries a huge burden globally and the number of heart valve procedures are projected to increase from the current 300 000 to 800 000 annually by 2050. Since its genesis 50 years ago, pericardial heart valve has moved leaps and bounds to ever more ingenious designs and manufacturing methods with parallel developments in cardiology and cardiovascular surgical treatments. This feat has only been possible through close collaboration of many scientific disciplines in the fields of engineering, material sciences, basic tissue biology, medicine and surgery. As the pace of change continues to accelerate, we ask the readers to go back with us in time to understand developments in design and function of pericardial heart valves. This descriptive review seeks to focus on the qualities of pericardial heart valves, the advantages, successes and failures encapsulating the evolution of surgically implanted pericardial heart valves over the past five decades. We present the data on comparison of the pericardial heart valves to porcine valves, discuss structural valve deterioration and the future of heart valve treatments.

Aortic valve replacement in sheep with a novel trileaflet mechanical heart valve prosthesis without anticoagulation

Background

Even after decades of intensive research, an ideal heart valve prosthesis remains elusive. Shortcomings of conventional devices include reduced durability of bioprostheses and the thrombogenicity of mechanical substitutes, necessitating anticoagulation and resulting in imperfect hemodynamics. Here we present in vivo results of a novel mechanical heart valve prosthesis aiming for freedom from anticoagulation.

Methods

Four female sheep had their aortic valves replaced using the novel mechanical heart valve (size 21 mm), with no postoperative anticoagulation treatment. This trileaflet heart valve was designed with the pivots in the systolic central flow. Hemodynamics, biochemistry, hematology, and macroscopy and microscopy were studied at 90 days in 2 sheep and at 1 year in the other 2 sheep.

Results

Mean (<6 mm Hg) and peak (<10 mm Hg) aortic transvalvular gradients remained low during the study period. Aortic regurgitation was trivial, and central traces were only rarely observed. The rate of thrombotic events was very low, with none macroscopically and microscopically visible thrombotic material on the device. Biochemistry and hemotology were unchanged without hemolysis. In 3 sheep, the fibrous pannus and mitral leaflet were partially folded over the edge of the annular body. Apart from organic/inorganic deposits on the leaflets after 1 year, the ultrastructurally evaluated leaflets were similar to those of nonimplanted controls.

Conclusions

The preliminary in vivo results of this novel anticoagulation-free aortic mechanical heart valve are promising with excellent hemodynamics and a very low risk of thrombotic events.