Multicentered European Study on Safety and Effectiveness of the On-X Prosthetic Heart Valve: Intermediate Follow-Up

Hemodynamic Comparison of the On-X and Top Hat Mechanical Aortic Valve Prostheses

BACKGROUND

There are limited data comparing hemodynamic valve function in mechanical aortic valve prostheses. This study compared the hemodynamic function of 2 commonly used mechanical aortic valve (AV) prostheses, the On-X (Artivion) and Top Hat (CarboMedics Inc) valves.

METHODS

This study was a retrospective analysis of 512 patients who underwent AV replacement with the On-X (n = 252; 49%) or Top Hat (n = 260; 51%) mechanical valves between 2011 and 2019. Patients were matched on the basis of selected variables. Echocardiographic data were collected preoperatively and postoperatively over a median follow-up of 1.39 years.

RESULTS

A total of 320 patients were matched, 160 patients in each group. Despite being matched for left ventricular outflow tract diameter, patients in the Top Hat group received a greater prevalence of smaller tissue annulus diameter valves (≤21 mm) (83% vs 38%; P < .001). Patients in the On-X group had longer aortic cross-clamp times (78 minutes vs 64 minutes; P < .001) during isolated aortic valve replacement. Discharge echocardiography showed no difference in the AV area index between both groups (1.00 cm2/m2 vs 1.02 cm2/m2; P = .377). During longer-term echocardiographic follow-up, the AV area index remained stable for both valves within their respective tissue annulus diameter groups (P = .060).

CONCLUSIONS

There was no difference between the 2 valves with respect to the AV area index at discharge, and hemodynamic function was stable during longer-term follow-up. The longer aortic cross-clamp time observed in the On-X group may indicate increased complexity of implantation compared with the Top Hat group.

Long-term evaluation of TTK Chitra™ heart valve prosthesis - a retrospective-prospective cohort study

Purpose

The TTK Chitra™ heart valve has more than 1,40,000 implantations so far, but no long-term data has been published. This study aims to provide long-term results of the valve.

Methodology

A cohort of 476 patients with implantations from January 2006 to December 2018 were followed up prospectively consisting of 104 aortic valve replacement (AVR), 87 double valve replacement (DVR), and 285 mitral valve replacement (MVR) patients. Total follow-up was 4079 patient-years (py) (AVR = 983, MVR = 2392, DVR = 704), being 96% complete.

Results

The results showed that actuarial survival at 15 years was 82.3% for AVR, 60.7% for MVR, and 52.2% for DVR. Freedom from all valve-related mortality and morbidity at 15 years was 73.8%, 64.8%, and 61.9% for AVR, MVR, and DVR, respectively. There was one instance of structural failure of valve disc leading to severe valvar regurgitation. Valve thrombosis incidence was 1 in AVR (0.1%/py), 6 in MVR (0.25%/py), and 1 in DVR (0.14%/py). Thrombo-embolic episodes occurred in 50 patients (AVR = 7 patients at 0.7%/py; MVR = 36 patients at 1.5%/py; DVR = 7 patients at 0.99%/py) and major hemorrhage (bleeding) in 24 patients (AVR = 0.61%/py; MVR = 0.5%/py; and DVR = 0.85%/py). The linearized rates of adverse events in this study were found to be lower than earlier published results.

Conclusion

The results highlight the continued safety and performance of the TTK Chitra™ heart valve (TTKCHV) in the long term at 15 years.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12055-022-01437-9.

PROSE: Prospective Randomized Trial of the On-X Mechanical Prosthesis and the St Jude Medical Mechanical Prosthesis Evaluation: Part 2: Study results-prostheses, positions, and economic development

Objectives

The Prospective Randomized On-X Mechanical Prosthesis Versus St Jude Medical Mechanical Prosthesis Evaluation (PROSE) trial purpose was to investigate whether a current-generation mechanical prosthesis (On-X; On-X Life Technologies/Artivion Inc) reduced the incidence of thromboembolic-related complications compared with a previous-generation mechanical prosthesis (St Jude Medical Mechanical Prosthesis; Abbott/St Jude Medical). This second report documents the valve-related complications by individual prostheses and by Western and Developing populations.

Methods

The PROSE trial study was conducted in 28 worldwide centers and incorporated 855 subjects randomized between 2003 and 2016. The study enrollment was discontinued on August 31, 2016. The study protocol, and analyses of 10 demographic variables and 24 risk factors were published in detail in 2021.

Results

The total patient population (N = 855) included patients receiving an On-X valve (n = 462) and a St Jude Medical valve (n = 393). The overall freedom evaluation showed no differences at 5 years between the prostheses for thromboembolism or for valve thrombosis. There were also no differences in mortality. There were several differences between Developing and Western populations. The freedom relations at 5 years for mortality favored Western over Developing populations. Valve thrombosis was differentiated by position and site: aortic < mitral (P = .007) and Western < Developing (P = .005). In the mitral position there were no cases in Western populations, whereas there were 8 in Developing populations (P = .217).

Conclusions

The On-X valve and St Jude Medical valve performed equally well in the study with no differences found. The only differentiation occurred with valve thrombosis in the mitral position more than the aortic position and occurring in Developing more than Western populations. The occurrence of valve thrombosis was also related to a younger population possibly due to anticoagulation compliance based on record review.

PROSE: Prospective Randomized Trial of the On-X Mechanical Prosthesis and the St Jude Medical Mechanical Prosthesis Evaluation : Part 1(Patient Dynamics): Preoperative demographics and preoperative and operative risk factors

OBJECTIVES

The PROSE trial purpose is to investigate whether the incidence of thromboembolic-related complications is reduced with a current generation mechanical prosthesis (On-X Life Technologies/CryoLife Inc.-On-X) compared with a previous generation mechanical prosthesis (St Jude Medical-SJM). The primary purpose of the initial report is to document the preoperative demographics, and the preoperative and operative risk factors by individual prosthesis and by Western and Developing populations.

METHODS

The PROSE study was conducted in 28 worldwide centres and incorporated 855 subjects randomized between 2003 and 2016. The study enrollment was discontinued on August 31, 2016. The preoperative demographics incorporated age, gender, functional class, etiology, prosthetic degeneration, primary rhythm, primary valve lesion, weight, height, BSA and BMI. The preoperative and operative evaluation incorporated 24 risk factors.

RESULTS

The total patient population (855) incorporated On-X population (462) and the St Jude Medical population (393). There was no significant difference of any of the preoperative demographics between the On-X and SJM groups. The preoperative and operative risk factors evaluation showed there was no significant difference between the On-X and St Jude Medical populations. The preoperative and operative risk factors by valve position (aortic and mitral) also documented no differentiation. The dominant preoperative demographics of the Western world population were older age, male gender, sinus rhythm, aortic stenosis, congenital aortic lesion, and mitral regurgitation. The dominant demographics of the Developing world population were rheumatic etiology, atrial fibrillation, aortic regurgitation, mixed aortic lesions, mitral stenosis and mixed mitral lesions. The Developing world group had only one significant risk factor, congestive heart failure. The majority of the preoperative and operative risk factors were significant in the Western world population.

CONCLUSIONS

The preoperative demographics do not differentiate the prostheses but do differentiate the Western and Developing world populations. The preoperative and operative risk factors do not differentiate the prostheses BUT do differentiate the Western and Developing world populations.

Long-Term Clinical Outcomes of the On-X Mechanical Prosthetic Valve in the Aortic or Mitral Position - A Single-Center Experience of up to 20 Years' Follow up

BACKGROUND

This study evaluated the long-term outcomes for up to 20 years after On-X mechanical valve implantation in the left side of the heart.Methods and Results:Between 1999 and 2015, 861 patients (mean age=51.6±10.9 years) who underwent prosthetic valve replacement using the On-X valve in the aortic or mitral position were enrolled (aortic=344, mitral=325, double=192). The mean clinical follow-up duration was 10.5±5.3 (median 10.9) years. Operative mortality occurred in 26 patients (3.0%), and linearized late cardiac mortality was 0.9%/patient-year without an intergroup difference. Linearized thromboembolism, bleeding, prosthetic valve endocarditis, non-structural valve deterioration (NSVD), and reoperation rates were 0.8%/patient-year, 0.6%/patient-year, 0.2%/patient-year, 0.5%/patient-year, and 0.5%/patient-year, respectively. Prosthetic valve endocarditis was more frequent after double valve replacement than after aortic or mitral valve replacement (P=0.008 and 0.005, respectively). NSVD and reoperation rates were significantly lower aortic valve replacement than after mitral or double valve replacement (P=0.001 and 0.002, P=0.001 and <0.001, respectively). Valve replacement in the mitral position was the only risk factor for NSVD (hazard ratio [95% confidence interval]=5.247 [1.608-17.116], P=0.006).

CONCLUSIONS

On-X valve implantation in the left side heart had favorable clinical outcomes with acceptable early and late mortality and a low incidence of prosthetic valve-related complications. Particularly in the aortic position, the On-X valve had better long-term non-structural durability.

Mechanical Hemolysis Complicating Transcatheter Interventions for Valvular Heart Disease: JACC State-of-the-Art Review

Mechanical intravascular hemolysis is frequently observed following procedures on heart valves and uncommonly observed in native valvular disease. In most cases, its severity is mild. Nevertheless, it can be clinically significant and even life threatening, requiring multiple blood transfusions and renal replacement therapy. This paper reviews the current knowledge on mechanical intravascular hemolysis in valvular disease, before and after correction, focusing on pathophysiology, approach to diagnosis, and impact of other hematological conditions on the resultant anemia. The importance of a multidisciplinary management is underscored. Laboratory data are provided about subclinical hemolysis that is commonly observed following the implantation of surgical and transcatheter valve prostheses and devices. Finally, clinical scenarios are reviewed and current medical and surgical treatments are discussed, including alternative options for inoperable patients.

Intravascular haemolysis after transcatheter aortic valve implantation with self-expandable prosthesis: incidence, severity, and impact on long-term mortality

We aimed to determine the incidence, severity, and long-term impact of intravascular haemolysis after self-expanding transcatheter aortic valve implantation (TAVI). We believe this should be evaluated before extending the indications of TAVI to younger low-risk patients. Prospective, academic, single centre study of 94 consecutive patients treated with supra-annular self-expandable TAVI prosthesis between April 2009 and January 2014. Haemolysis at 1-year post-TAVI was defined per the published criteria based on levels of haemoglobin, reticulocyte and schistocyte count, lactate dehydrogenase (LDH), and haptoglobin. All patients had long-term clinical follow-up (6 years). The incidence of haemolysis at 1-year follow-up varied between 9% and 28%, based on different haemolysis definitions. Haemolysis was mild in all cases, no patient had markedly increased LDH levels. The presence of moderate/severe paravalvular aortic regurgitation was associated with haemolysis (7.7% vs. 23.1%, P = 0.044) and aortic valve area post-TAVI did not differ between groups with or without haemolysis (1.01 vs. 0.92 cm²/m², P = 0.23) (definition including schistocyte count). The presence of haemolysis did not have any impact on patient prognosis after 6 years with log-rank test P = 0.80. Intravascular haemolysis after TAVI with self-expandable prosthesis is present in 9–28% of patients depending on the definition of haemolysis. The presence of haemolysis is associated with moderate/severe paravalvular aortic regurgitation but not with post-TAVI aortic valve area. Haemolysis is mild with no impact on prognosis.

Spontaneous rupture of a mechanical valve in a mitral position (On-X) with migration-embolization to aortic bifurcation from the perspective of the vascular surgeon

We report on the case of spontaneous rupture of an On-X-pure pyrolytic carbon mechanical valve prosthesis implanted seven years earlier, in a mitral position, at our hospital. The patient was admitted with valvular dysfunction and acute pulmonary edema requiring emergency surgery (prosthesis replacement); the absence of a leaflet was confirmed intraoperatively. The patient presented severe respiratory failure, which prolonged the postoperative period. A CT scan showed that the migrated leaflet was located in the aortic bifurcation with no apparent arterial lesion. Four months later, once the patient had recovered, laparotomy and aortotomy were performed in order to retrieve the leaflet, which was found to have become included (neoendothelized) in the aortic wall without compromising the latter's integrity or obstructing the blood flow. A subsequent CT scan confirmed the persistence of the leaflet in its initial position. The literature review highlights two singular facts: 1) this is the second published case of the escape of a leaflet from an On-X prosthesis (the first patient died); 2) this is the first case in which a laparotomy was performed to retrieve the leaflet but finally a decision was made to leave it in situ. Seven months later, the patient remained asymptomatic.

Effect of Aortic Wall Deformation with Healthy and Calcified Annulus on Hemodynamic Performance of Implanted On-X Valve

INTRODUCTION

In this research, the hemodynamic performance of a 23-mm On-X bileaflet mechanical heart valve (BMHV) was investigated with the realistic geometry model of the valve and the deformable aorta in accelerating systole. In addition, the effect of ascending aorta flexibility and aortic annulus calcification on the complex blood flow characteristics were investigated.

METHODS

The geometry of the aorta is derived from the medical images, and the Ogden model has been utilized for the mechanical behavior of the ascending aorta. The 3D numerical simulation by a two-way Fluid-Structure Interaction (FSI) analysis using the Arbitrary Lagrangian-Eulerian (ALE) method was performed throughout the accelerating systolic phase.

RESULTS

The dynamics of the leaflets are investigated, and blood flow characteristics such as velocities, vorticities as well as viscous and turbulent shear stress were precisely captured in the flow domain specifically in the hinge region. Streamline results are in accordance with the previously reported data, which show that the flared On-X valves inlet yields a more uniform flow in accelerating systole. Simulations show that aorta flexibility or valve annulus calcification causes variations up to 7% in maximum fluid velocity and 20% in Turbulence Kinetic Energy (TKE).

CONCLUSIONS

In this study, the complex flow field characteristics in the new generation of BMHVs considering aorta flexibility with healthy and calcified annulus were investigated. It was found that the blood flow around the hinges region is in the danger of hemolysis and platelet activation and subsequently thromboembolism. Furthermore, the results show that similar to vessel wall deformation, considering the probable annulus calcification after valve replacement is also essential.

Anticoagulation and Antiplatelet Strategies After On-X Mechanical Aortic Valve Replacement

BACKGROUND

The burden oral anticoagulation is a limitation of mechanical valve prostheses.

OBJECTIVES

The aim of this study was to test whether patients could be safely managed with dual-antiplatelet therapy (DAPT) (aspirin 325 mg and clopidogrel 75 mg) or lower warfarin after On-X mechanical aortic valve replacement (mAVR).

METHODS

PROACT (Prospective Randomized On-X Anticoagulation Trial) (n = 576) is a multicenter (41 sites) noninferiority trial. From June 2006 through February 2014, 201 patients ≥18 years of age without thromboembolic risk factors undergoing mAVR were randomized to receive DAPT (n = 99) or standard warfarin plus aspirin (n = 102) 3 months after mAVR (low-risk arm). From June 2006 through October 2009, 375 patients with 1 or more thromboembolic risk factors were also randomized to lower intensity warfarin plus aspirin (international normalized ratio 1.5 to 2.0; n = 185) or standard warfarin plus aspirin (international normalized ratio 2.0 to 3.0; n = 190) 3 months after mAVR (high-risk arm).

RESULTS

The low-risk arm was terminated for excess cerebral thromboembolic events (3.12% per patient-year vs. 0.29% per patient-year, p = 0.02) in the DAPT group at up to 8.8-year follow-up (631.6 patient-years), with no differences in bleeding or all-cause mortality. High-risk arm patients experienced significantly lower major (1.59% per patient-year vs. 3.94% per patient-year, p = 0.002) and minor (1.27% per patient-year vs. 3.49% per patient-year, p = 0.002) bleeding up to 8.7-year follow-up (2,035.2 patient-years), with no differences in thromboembolism (0.42% per patient-year vs. 0.09% per patient-year, p = 0.20) and all-cause mortality.

CONCLUSIONS

DAPT was associated with higher rates of thromboembolism and valve thrombosis compared with control in the low-risk arm. International normalized ratios were safely maintained at 1.5 to 2.0 in high-risk patients, without differences in mortality or thromboembolic complications. (Randomized On-X Anticoagulation Trial [PROACT]; NCT00291525).

On-X mitral valve replacement: a single-centre experience in 318 patients

OBJECTIVES

If mitral valve repair is not feasible, mitral valve replacement remains the only option. Based on our overall experience with the On-X mitral valve, the aim of this study was to investigate early and late outcomes after mitral valve replacement using this latest generation prosthesis.

METHODS

From 1998 to 2016, 600 patients received an On-X prosthesis in the mitral position. Of them, we excluded all patients who had combined aortic procedures and retrospectively analysed 318 consecutive patients who had a mitral valve replacement. Associated procedures (53.5%) were tricuspid valve repair, coronary artery bypass graft and the maze procedure. The mean follow-up time was 5.6 ± 4.0 years.

RESULTS

The overall hospital mortality rate was 4.4%, including acute cases of ischaemic mitral regurgitation (9.4%) and infective endocarditis (9.4%). Survival rates at 1, 3, 5 and 10 years were 97.8 ± 1.0%, 92.4 ± 1.7%, 88.4 ± 2.2% and 70.9 ± 4.0%, respectively. Independent predictors of late mortality were hypertension [hazard ratio (HR) 1.91; P = 0.027], chronic obstructive pulmonary disease (HR 2.91; P = 0.003) and chronic renal failure (HR 5.27; P < 0.001). Freedom from reoperation was 99.3 ± 0.5%, 98.4 ± 0.8%, 97.2 ± 1.2% and 92.5 ± 2.4% at 1, 3, 5 and 10 years, respectively. At follow-up, 8.5% events were recognized as thromboembolic or haemorrhagic events; freedom from events related to anticoagulation therapy at 1, 3, 5 and 10 years was 99.0 ± 0.6%, 96.8 ± 1.1%, 93.7 ± 1.8% and 89.0 ± 2.7%, respectively.

CONCLUSIONS

According to the results of this observational study, the unique design of the On-X valve works well with mitral valve diseases of various aetiologies, especially in cases with an unfavourable anatomy. This prosthesis also guarantees safe long-term durability associated with a low incidence of thromboembolism.

Cardiac prostheses-related hemolytic anemia

Hemolysis is an unintended sequel of temporary or permanent intracardiac devices. However, limited data exist on the characteristics and treatment of hemolysis in patients with cardiac prostheses. This entity, albeit uncommon, often poses significant diagnostic and management challenges to the clinical cardiologist. In this article, we aim to provide a contemporary overview of the incidence, mechanisms, diagnosis, and management of cardiac prosthesis‐related hemolysis.

A turbulence in vitro assessment of On-X and St Jude Medical prostheses

OBJECTIVE

The objective of this study was to investigate and compare the hemodynamic and turbulence characteristics upon implantation of St Jude Medical (SJM) (St Jude Medical, St Paul, Minn) and On-X (On-X Life Technologies, Kennesaw, Ga) bileaflet mechanical valves. Both valves are considered highly successful bileaflet mechanical valves characterized by good clinical outcomes despite their numerous design differences. Although thromboembolism remains the main disadvantage of bileaflet mechanical valves, On-X valves have been shown to need less anticoagulation therapy.

METHODS

Hemodynamic assessment of a 23-mm On-X bileaflet mechanical valve and a 23-mm bileaflet SJM valve implanted in an aortic root was performed under pulsatile physiologic conditions. Time-resolved and phase-locked particle-image-velocimetry images and high-speed imaging data were acquired. Pressure gradients, effective orifice areas, dimensionless area index, leaflet position tracking, velocity, and principal Reynolds shear stress were calculated.

RESULTS

Pressure gradient for the On-X valve was 4.15 ± 0.099 mm Hg versus 4.75 ± 0.048 mm Hg for SJM (P < .001). Effective orifice area for the On-X valve was 2.61 ± 0.045 cm² versus 2.36 ± 0.022 cm² for SJM (P < .001). Area index was higher with SJM (0.87 ± 0.008) than with On-X (0.73 ± 0.013) (P < .001). On-X showed fluctuating leaflet behavior during systole, whereas SJM leaflets were stable. At peak systole, the maximal velocity with On-X was 1.86 m/s versus 2.33 m/s with SJM. Reynolds shear stress was higher with On-X compared with SJM at peak systole (95 vs 72 Pa). Higher velocity fluctuation was noted with the On-X valve.

CONCLUSIONS

This study shows that despite the design differences that characterize the On-X valve, the hemodynamic and turbulence parameters were not necessarily improved compared with SJM.

Antithrombotic Management of Patients With Prosthetic Heart Valves

Valvular heart disease is a major public health issue. The prevalence of valvular heart disease is expected to increase due to an aging population. Valve dysfunction manifests as valve stenosis, regurgitation, or both due to various etiologies. Valve repair and replacement are the main treatment options for severe valve dysfunction. Valve replacement is achieved by using either a mechanical or a bioprosthetic valve. Mechanical valves are more durable but require lifelong anticoagulation with associated complications. Bioprosthetic valves usually require anticoagulation only transiently after implantation but are less durable and degenerate more rapidly. In this article, we discuss antithrombotic regimens in persons after valve operations. We discuss general issues and antithrombotic recommendations for patients undergoing surgical bioprosthetic valve replacement, mechanical valve replacement (including different regimens for different positions and types of mechanical valves), mitral valve repair, and transcatheter aortic valve replacement. In addition, we discuss the antithrombotic management of patients in special circumstances, including patients with mechanical valves who have recurrent bleeding or thrombotic events, patients with mechanical valves undergoing surgery, and pregnant women with mechanical valves.

On-X versus St Jude Medical Regent mechanical aortic valve prostheses: early haemodynamics

Objective

We aimed to compare the early haemodynamic data of the On-X and St Jude Medical (SJM) Regent bileaflet mechanical prostheses in the aortic position.

Methods

A retrospective study was performed using data collected prospectively for a national database. Thirty-three patients who had aortic On-X valve (On-X group) and 33 matched patients who had aortic SJM Regent valve (SJM group) were included. The intraoperative and early postoperative data were collected. The same echocardiographer reviewed all the echocardiograms and obtained the required parameters.

Results

The peak gradient across the prosthetic valve was comparable between the two groups except for the labelled valve size of 25 mm for which the On-X group had lower peak gradient when compared with the SJM group. Mean gradients and effective orifice area indices of the two valve types within each valve size subgroup were comparable.

Conclusions

The current study confirms that in the early postoperative period, the two valve types had comparable haemodynamic outcomes.

Anticoagulation for prosthetic heart valves: unresolved questions requiring answers

PURPOSE OF REVIEW

The efficacy of anticoagulation for valvular prostheses is the result of a delicate balance between the risk of thromboembolic (TE) events and bleeding. Here, we review data on anticoagulation for valve prostheses with a focus on clinical trials that address key unanswered questions.

RECENT FINDINGS

There are several unanswered questions in the field of prosthetic valve anticoagulation, including: optimal TE prophylaxis in the short term for bioprostheses, optimal TE prophylaxis following transcatheter aortic valve implantation, the safety and efficacy of lower levels of anticoagulation with the bileaflet mechanical prosthesis, the role of aspirin for patients with mechanical prostheses, and the management of anticoagulation for mechanical valves in pregnancy. Other areas of study include the role, if any, of nonwarfarin oral anticoagulants for prosthetic TE prophylaxis as well as self-INR monitoring. Finally, we briefly mention studies of newer anticoagulants, such as novel vitamin K antagonists and antisense oligonucleotides, that are on the horizon.

SUMMARY

Optimal antithrombotic management is a key issue for patients with valvular prostheses, and the publication of recent trials has provided much-needed guidance. We highlight areas of progress, in addition to the major unanswered questions for which well-designed, prospective clinical trials are forthcoming.

On-X Heart Valve Prosthesis: Numerical Simulation of Hemodynamic Performance in Accelerating Systole

Numerical simulation of the bileaflet mechanical heart valves (BMHVs) has been of interest for many researchers due to its capability of predicting hemodynamic performance. A lot of studies have tried to simulate this three-dimensional complex flow in order to analyze the effect of different valve designs on the blood flow pattern. However, simplified models and prescribed motion for the leaflets were utilized. In this paper, transient complex blood flow in the location of ascending aorta has been investigated in a realistic model by fully coupled simulation. Geometry model for the aorta and the replaced valve is constructed based on the medical images and extracted point clouds. A 23-mm On-X Medical BMHV as the new generation design has been selected for the flow field analysis. The two-way coupling simulation is conducted throughout the accelerating phase in order to obtain valve dynamics in the opening process. The complex flow field in the hinge recess is captured precisely for all leaflet positions and recirculating zones and elevated shear stress areas have been observed. Results indicate that On-X valve yields relatively less transvalvular pressure gradient which would lower cardiac external work. Furthermore, converging inlet leads to a more uniform flow and consequently less turbulent eddies. However, the leaflets cannot open fully due to middle diffuser-shaped orifice. In addition, asymmetric butterfly-shaped hinge design and converging orifice leads to better hemodynamic performance. With the help of two-way fluid solid interaction simulation, leaflet angle follows the experimental trends more precisely rather than the prescribed motion in previous 3D simulations.

Anticoagulation dilemma in a high-risk patient with On-X valves

Thromboembolism continues to be a major concern in patients with mechanical heart valves, especially in those with unsatisfactory anticoagulation levels. The new On-X valve (On-X Life Technologies, Austin, TX, USA) has been reported as having unique structural characteristics that offer lower thrombogenicity to the valve. We report a case where the patient received no or minimal systemic anticoagulation after placement of On-X mitral and aortic valves due to development of severe mucosal arterio-venous malformations yet did not show any evidence of thromboembolism. This case report reinforces the findings of recent studies that lower anticoagulation levels may be acceptable in patients with On-X valves and suggests this valve may be particularly useful in those in whom therapeutic levels of anticoagulation cannot be achieved due to increased risk of bleeding.

A Meta-Analysis Examining Differences in Short-Term Outcomes between Sutureless and Conventional Aortic Valve Prostheses

Objective

Sutureless aortic valve prostheses are anchored by radial force in a mechanism similar to that of transcatheter aortic valve implantation. Transcatheter aortic valve implantation is associated with an increased permanent pacemaker (PPM) requirement in a significant proportion of patients. We undertook a meta-analysis to examine the incidence of PPM insertion associated with sutureless compared with conventional surgical aortic valve replacement.

Methods

A systematic review was conducted in accordance with the Prisma guidelines.1 All searches were performed on August 10, 2014. Studies between 2007 and 2014 were included in the search.

Results

A total of 832 patients were included in the sutureless group and 3,740 in the conventional group. Aortic cross-clamp (39.8 vs 62.4 minutes; P < 0.001) and cardiopulmonary bypass (64.9 vs 86.7 minutes; P = 0.002) times were shorter in the sutureless group. Permanent pacemaker implantation rate was higher in the sutureless cohort (9.1% vs 2.4%; P = 0.025).

Conclusions

Sutureless aortic valve prostheses are associated with significantly shorter cardiopulmonary bypass and aortic cross-clamp times and a higher incidence of PPM insertion than conventional. Further investigation of the prognostic significance is required.

CardiaMed mechanical valve: mid-term results of a multicenter clinical trial

BACKGROUND

Prosthesis choice is a major concern in valvular surgery.

METHODS

A multicenter clinical trial was performed to assess the efficacy and safety of the CardiaMed prosthetic heart valve. The study enrolled 420 patients who underwent mitral (209) or aortic (211) valve replacement from 2003 to 2004 at 7 institutions in Russia, and who were followed up from 2006 to 2011. The mean age was 52.2 ± 10.2 years (range, 12-78 years), 47.4% were female, and 99.05% completed the study.

RESULTS

The maximum observation term was 7.5 years (2188.5 patient-years); 1081.6 patient-years for aortic and 1106.9 patient-years for mitral valve replacement. The overall 7-year survival rate was 85.1%  ± 3.7%; 86.1%  ± 4.8% and 84.4%  ± 5.4% for aortic and mitral valve replacement, respectively. The 7-year freedom from valve-related death was 93.9%  ± 3.7% and 94.5%  ± 3.2% for aortic and mitral valve replacement, respectively. When early mortality (<30 days) was excluded, these rates were 94.8%  ± 3.1% and 93.8%  ± 3.82%, respectively. Linearized valve-dependent complication rates were determined for structural valve failure (0%/patient-year overall), thrombosis (0.63%/patient-year, all for mitral valve replacement), thromboembolic complications including transient neurologic deficits (0.13%/patient-year overall, 0.5%/patient-year for aortic valve replacement, 0.8%/patient-year for mitral valve replacement), hemorrhagic bleeding (0.64%/patient-year overall, 0.55%/patient-year for aortic valve replacement, 0.09%/patient-year for mitral valve replacement), prosthetic endocarditis (0.28%/patient-year overall, 0.28%/patient-year for aortic valve replacement, 0%/patient-year for mitral valve replacement), and hemolysis (0%/patient-year overall).

CONCLUSION

The CardiaMed mechanical heart valve prostheses meets world standards of safety and efficacy.

Anticoagulation for prosthetic valves

Implantation of prosthetic valve requires consideration for anticoagulation. The current guideline recommends warfarin on all mechanical valves. Dabigatran is the new generation anticoagulation medication which is taken orally and does not require frequent monitoring. This drug is approved for treatment for atrial fibrillation and venous thromboembolism, but the latest large trial showed that this drug increases adverse events when used for mechanical valve anticoagulation. On-X valve is the new generation mechanical valve which is considered to require less anticoagulation due to its flow dynamics. The latest study showed that lower anticoagulation level lowers the incidence of bleeding, while the risk of thromboembolism and thrombosis remained the same. Anticoagulation poses dilemma in cases such as pregnancy and major bleeding event. During pregnancy, warfarin can be continued throughout pregnancy and switched to heparin derivative during 6-12 weeks and >36 weeks of gestation. Warfarin can be safely started after 1-2 weeks of discontinuation following major bleeding episode.

Twelve years of experience with the ATS mechanical heart valve prostheses

OBJECTIVE

The ATS Open Pivot mechanical heart valve has been implanted routinely at our institution since 1999. The objective of this study is to retrospectively analyze our 12-year clinical results with ATS prostheses.

METHODS

ATS Open Pivot mechanical valves were implanted in 268 adult patients between May 1999 and August 2010. We selected 259 subjects who could be adequately followed (follow-up rate 96.6 %). Aortic valve replacement was performed in 157 patients, mitral valve replacement (MVR) in 71, and double (aortic and mitral) valve replacements (DVR) in 31. Mean age at the time of implant was 58.8 ± 10.6 years. The gender ratio was 128 males/131 females. Mean follow-up was 4.4 ± 7.8 years, and the cumulative follow-up was 1144 patient-years (pt-yr).

RESULTS

Early death within 30 days after the operation occurred in 5 (2.5 %) patients. Late death occurred in 27 patients including valve-related deaths in 13. The 10-year survival rate after the operation was 82.7 ± 2.9 %. The rate of freedom from valve-related death was 92.2 ± 2.2 %. The incidence of valve-related complications was 2.19 %/pt-yr. Of these, the incidence of thromboembolic events and that of bleeding complications were 1.22 and that 0.87 %/pt-yr. The incidence of valve thrombosis was 0.09 %/pt-yr. No structural valve deterioration was observed in any of the three operative procedure groups.

CONCLUSIONS

Our 12-year experience with aortic and MVR using the ATS mechanical heart valve demonstrated low incidences of thromboembolic events, bleeding complications, and valve thrombosis.

Clinical event rates with the On-X bileaflet mechanical heart valve: a multicenter experience with follow-up to 12 years

OBJECTIVE

The aim of the study was to establish clinical event rates for the On-X bileaflet mechanical heart valve (On-X Life Technologies Inc, Austin, Tex) using an audit of data from the 3 centers within Europe with the longest history of implanting.

METHODS

All patients receiving the On-X valve between March 1, 1998, and June 30, 2009, at 3 European centers were studied. Data were collected using questionnaire and telephone surveys augmented by outpatient visits and examination of clinical records.

RESULTS

There were 691 patients, with a mean age of 60.3 years, who received 761 valves in total: 407 mitral valve replacements, 214 aortic valve replacements, and 70 aortic + mitral valve replacements (dual valve replacement). Total follow-up was 3595 patient-years, with a mean of 5.2 years (range, 0-12.6 years). Early (≤ 30 days) mortality was 5.4% (mitral valve replacement), 0.9% (aortic valve replacement), and 4.3% (dual valve replacement). Linearized late (>30 days) mortality expressed per patient-year was 3.6% (mitral valve replacement), 2.2% (aortic valve replacement), and 4.1% (dual valve replacement), of which valve-related mortality was 0.5% (mitral valve replacement), 0.2% (aortic valve replacement), and 1.8% (dual valve replacement). Late linearized thromboembolism rates were 1.0% (mitral valve replacement), 0.6% (aortic valve replacement), 1.8% (dual valve replacement). Bleeding rates were 1.0% (mitral valve replacement), 0.4% (aortic valve replacement), and 0.9% (dual valve replacement). Thrombosis rates were 0.1% (mitral valve replacement), 0% (aortic valve replacement), and 0.3% (dual valve replacement). Reoperation rates were 0.6% (mitral valve replacement), 0.2% (aortic valve replacement), and 1.2% (dual valve replacement).

CONCLUSIONS

The On-X valve has low adverse clinical event rates in longer-term follow-up (mean 5.2 years and maximum 12.6 years).

Valvular heart disease: a primer for the clinical pharmacist

Valvular heart disease is a commonly encountered clinical condition that is not taught in most undergraduate and graduate pharmacy programs, leaving the practicing pharmacist without basic knowledge to expand on and subsequently apply to direct patient care. Unlike other areas of cardiology in which thousands of patients are recruited in many well-designed randomized clinical trials, data assessing treatments for valvular heart disease are limited and often consist of retrospective case series or observations. Our goal is to provide a basic overview of chronic valvular heart disease, with emphasis on describing the common conditions requiring surgery and the available options, as well as common pharmacologic therapies used in this patient population. Anomalies in valves can be broadly classified as stenosis and regurgitation. Depending on the valve and the type of anomaly, the impact on the cardiovascular system will vary. Understanding the hemodynamic consequences of aortic stenosis, aortic regurgitation, mitral stenosis, and mitral regurgitation is imperative to effectively counsel patients surrounding disease progression and self-monitoring, use of vasodilators, and prophylaxis for endocarditis and rheumatic fever. Further, patient characteristics factored into the choice of implanting either a bioprosthetic (tissue) or prosthetic (metal) valve encompass patient choice, life expectancy, and willingness or ability to accept lifelong anticoagulation therapy. The evolution of metal valves has resulted in newer generations under clinical study that have more laminar flow (minimizing interaction with blood products) and improved pyrolytic carbon (minimizing infection and interaction with blood products). Although antithrombotic therapy with warfarin is now mandatory in North America for all patients receiving metal valves, research is ongoing to assess the need with the most recent generation of valves.

Antithrombotic management of patients with prosthetic heart valves: current evidence and future trends

Over 4 million people worldwide have received a prosthetic heart valve, and an estimated 300,000 valves are being implanted every year. Prosthetic heart valves improve quality of life and survival of patients with severe valvular heart disease, but the need for antithrombotic therapy to prevent thrombotic complications in valve recipients poses challenges for clinicians and patients. Here, we review antithrombotic therapies for patients with prosthetic heart valves and management of thromboembolic complications. Advances in antithrombotic therapy and valve technologies are likely to improve the management of patients with prosthetic heart valves in developed countries, but the most important unmet need and potential for benefit from these new therapies is in developing countries where a massive and rapidly increasing burden of valvular heart disease exists.

In-vitro localization of initial flow-induced thrombus formation in bileaflet mechanical heart valves

A major concern with mechanical heart valve prostheses is still the need for lifelong anticoagulation to prevent valve thrombosis and thrombembolism. Knowledge of the localization of initial thrombus formation on the prosthesis may help to improve valve design. Since observation of early clot deposition in vivo is difficult, the aim of this study was a detailed assessment of the initial stages of thrombus formation at bileaflet mechanical heart valves by means of an in-vitro clotting model. Four different bileaflet mechanical heart valves (St. Jude Medical, CarboMedics, ATS and On-X) were investigated in a mock circulation in aortic position using enzyme-activated milk resembling blood clotting potential. Initial development of clot formation on the valves was documented photographically and frequency of occurrence was analyzed for both location and valve type. For the bileaflet valves, clot depositions could be found in a distinct pattern similar in all types. In initial stages, clots developed downstream of the leaflets near the orifice ring, 61.5+/-5.8% of which were hinge associated, but 38.5+/-5.8% were located isolated laterally and medially remote of the hinge region, providing new information on thrombus formation potentially useful for improvement of valve design.