The On-X prosthetic heart valve at five years1

Presented at the Eighth Annual Cardiothoracic Techniques and Technologies Meeting 2002, Miami Beach, FL, Jan 23–26, 2002.
https://doi.org/10.1016/S0003-4975(02)03968-1Get rights and content

Abstract

Background

Multicenter clinical trials were conducted in Europe and North America to evaluate the performance of the On-X bileaflet heart valve prosthesis (Medical Carbon Research Institute, Austin, TX).

Methods

A total of 532 patients underwent implantation, 303 for aortic valve replacement (AVR) and 229 for mitral valve replacement (MVR), at 20 centers from September 1996 to July 2001. The study followed the guidelines of the AATS/STS. Mean follow-up was 23 months (total 1024 patient-years; maximum 5 years). Poolability analysis was performed to show the equivalence of the populations.

Results

Patients and results were found to be similar and poolable. Freedom from adverse events at 2 years in the study were as follows: thromboembolism, 96.0% for AVR patients and 96.3% for MVR; thrombosis, 100% for AVR and 100% for MVR; bleeding events, 96.6% for AVR and 95.7% for MVR; and overall mortality, 95.2% for AVR and 92.4% for MVR. Median lactate dehydrogenate levels were in the normal range for AVR and MVR patients at all intervals. At 1 year, AVR echocardiographic results for the 19 to 25 valves, respectively, ranged from 1.5 to 2.8 cm2 for effective orifice area and 9.2 to 4.7 mm Hg for mean gradient, and MVR effective orifice area by pressure half-time was 2.8 cm2 and mean gradient was 4.2 mm Hg.

Conclusions

The two trials have given similarly excellent results for the On-X valve.

Section snippets

Patient population and surgery

From September 1996 to July 2001, a total of 532 patients had isolated valve replacement at 11 European and nine North American centers under a standardized protocol. Isolated aortic valve replacement (AVR) occurred in 303 (57%) patients, and isolated mitral valve replacement (MVR) in 229 (43%). In the AVR group, 68.6% of patients were male, whereas in the MVR group, 38% were male. The mean age at implant was 59.6 ± 9.1 years in AVR patients (range 20 to 85 years) and 59.2 ± 10.6 years in MVR

Mortality

Hospital mortality in the study was 2.44% (13/532) for the whole study, at 1.32% for AVR patients and 3.93% for MVR. One AVR patient died of multiple organ failure 6 weeks postoperatively without discharge from the hospital; thus, the 30-day mortality was 2.26% (0.99% for AVR and 3.93% for MVR). The 12 remaining deaths included 3 MVR patients from sepsis, 5 patients (2 AVR and 3 MVR) from arrhythmias determined by autopsy to be not related to the valve, 1 AVR patient from thromboembolism 10

Comment

As with all mechanical valves, a major concern is the long-term need for anticoagulation and the thrombogenic potential associated with these valves. Clinical studies of such valves rightly focus on thromboembolism, thrombosis, and bleeding rates, individually or as a collective index. In this study, patients were maintained on permanent anticoagulant therapy. The sum of the embolic and bleeding events in this study produced a freedom from these events at 2 years of 92.6% ± 1.2% AVR and 92.0% ±

Acknowledgements

The multicenter investigators in the On-X Prosthesis Heart Valve Trial are as follows: Europe: A. Laczkovics, Bochum, Germany; G. Laufer, Vienna, Austria; J. Pomar, Barcelona, Spain; D. Birnbaum, Regensburg, Germany; F. Hehrlein, Giessen, Germany; A. Haverich, Hannover, Germany; F. Mohr, Leipzig, Germany; H. Greve, Krefeld, Germany; H. Oelert, Mainz, Germany; D. Regensburger, Kiel, Germany; and G. Palatianos, Athens, Greece. North America: T. Ivey, Cincinnati, OH; G. Lemole, Newark, DE; S.

References (12)

  • L.H. Edmunds et al.

    Guidelines for reporting morbidity, and mortality after cardiac valvular operations

    Ann Thorac Surg

    (1996)
  • B.J. Gersh et al.

    Issues concerning the clinical evaluation of new heart valves

    J Thorac Cardiovasc Surg

    (1986)
  • J. Chambers et al.

    Early postoperative echocardiographic hemodynamic performance of the On-X Prosthetic Heart Valvea multicenter study

    J Heart Valve Dis

    (1998)
  • S. Fraund et al.

    On-X bileaflet valve in the aortic position—early experience shows an improved hemodynamic profile

    Thorac Cardiovasc Surg

    (1998)
  • E.L. Kaplan et al.

    Nonparametric estimation from incomplete observations

    J Am Stat Assoc

    (1958)
  • D. Horstkotte et al.

    The influence of prosthetic valve replacement on the natural history of severe acquired heart valve lesions valves

There are more references available in the full text version of this article.

Cited by (32)

  • The role of mechanical valves in the aortic position in the era of bioprostheses and TAVR: Evidence-based appraisal and focus on the On-X valve

    2022, Progress in Cardiovascular Diseases
    Citation Excerpt :

    This study was the first real-world demonstration of the exceptionally low incidence of valve thrombosis in On-X aortic valves.76 With the addition of other studies revealing low thromboembolic event rates,70,77 the path to the PROACT Trial was developed. The manufacturer-sponsored Prospective Randomized On-X Anticoagulation Clinical Trial (PROACT) study compared standard warfarin therapy (target INR 2.0 to 3.0) with either reduced warfarin (target INR 1.5 to 2.0) in the High-Risk arm, or dual antiplatelet therapy (DAPT) in the Low-Risk arm.27

  • Improving the hemocompatibility of heart valves

    2018, Hemocompatibility of Biomaterials for Clinical Applications: Blood-Biomaterials Interactions
  • Improving the hemocompatibility of heart valves

    2017, Hemocompatibility of Biomaterials for Clinical Applications: Blood-Biomaterials Interactions
  • Clinical event rates with the On-X bileaflet mechanical heart valve: A multicenter experience with follow-up to 12 years

    2013, Journal of Thoracic and Cardiovascular Surgery
    Citation Excerpt :

    Trials are in progress to investigate the safety of low anticoagulation rates in the On-X valve (PROACT; US registration NCT00291525). No structural failures were found, and none have been reported by other studies.3-6,10,11 This is similar to other types of bileaflet mechanical valve other than the St Jude Medical valve, the discontinued Hemex-Duromedics valve (originally Hemex Scientific Inc, Austin, Tex), and the Tekna-Edwards valve (originally Baxter Healthcare Corp, Santa Ana, Calif), for which a small number of leaflet escapes have been reported.11-13

  • Influence of the On-X mechanical prosthesis on intermediate-term major thromboembolism and hemorrhage: A prospective multicenter study

    2010, Journal of Thoracic and Cardiovascular Surgery
    Citation Excerpt :

    Instead, patients were managed by either the primary physician or the treating cardiac surgeon according to practice guidelines.15 Patients in this study were comparable in age to those of other studies describing outcomes after mechanical valve replacement.3-13 Overall, 6% (38/682) of patients had preoperative left ventricular ejection fraction of less than 35%, whereas concomitant CABG was performed in 13% (80/682) of patients.

  • Immediate and Long-Term Echocardiographic Findings after Transcatheter Aortic Valve Implantation for the Treatment of Aortic Stenosis: The Cribier-Edwards/Edwards-Sapien Valve Experience

    2010, Journal of the American Society of Echocardiography
    Citation Excerpt :

    The mean pressure gradient for mechanical and tissue prostheses ranges from 13 to 17 mm Hg, and the mean pressure gradient for the Cribier-Edwards valve is 10 ± 2 mm Hg. Only the On-X (Medical Carbon Research Institute, LLC, Austin, TX) shows similar results with an effective orifice area of approximately 2 cm2.26 Hemodynamic differences with the Cribier-Edwards/Edwards-Sapien valve may be explained by its particular manufacture.

View all citing articles on Scopus
1

The members of On-X Prosthesis Heart Valve Trial are listed in the Acknowledgments.

View full text