North American
Multicenter Experience with the On-X Prosthetic Heart Valve
Kathleen W. McNicholas, Tom D. Ivey,
Jacques Metras, Szabolcs Szentpetery, Steven W. Marra, Roy G. Masters,
Emery W. Dilling, Mark S. Slaughter, Michael J. Mack
Christiana Care Health System, Newark,
DE, USA, Ohio Heart Institute, Cincinnati, OH, USA, Hôpital
Laval, Quebec City, Canada, Sentara Norfolk General Hospital, Norfolk,
VA, USA, Cooper Hospital, Camden, NJ, USA, Ottawa Heart Center,
Ottawa, Ontario, Canada, St. David’s Hospital, Austin, TX,
USA, Christ Hospital, Oak Lawn, IL, USA, Medical City, Dallas,
TX, USA |
Background and aim of the study: This ongoing, longitudinal,
multi-center, North American study was designed to evaluate the safety
and effectiveness of the On-X® valve.
Methods: The On-X valve was implanted in isolated aortic (AVR) and mitral
(MVR) valve replacement patients at nine North American centers. Follow
up was 98.6% complete. Anticoagulation compliance was evaluated by collection
of international normalized ratio (INR) results in all patients throughout
their postoperative follow up. Adverse events were recorded according to
the AATS/STS guidance criteria. Hematologic studies were conducted postoperatively
to evaluate hemodynamics and hemolysis.
Results: In total, 142 AVR and 142 MVR implants were performed; the mean
follow up was 4.5 years; total follow up was 1,273 patient-years (pt-yr).
At implant, the mean patient age was 59.2 years (range: 28 to 85 years);
71.8% of patients who underwent AVR and 33.1% who underwent MVR were males.
Preoperatively, 89.4% of AVR patients and 56.3% of |
MVR patients were in sinus rhythm. The cardiac disease etiology was primarily
stenotic, calcific degeneration in AVR and rheumatic or degenerative
regurgitation in MVR. Hemolysis represented by postoperative elevation
of serum lactate dehydrogenase was very low (median 217 IU after AVR
and 251 IU after MVR at one year (82% AVR and 98% MVR of upper normal).
Late adverse event rates were low, most notably thromboembolism (0.9%/pt-yr
after AVR; 1.6%/pt-yr after MVR) and thrombosis. Kaplan-Meier event-free
rates at five years were correspondingly high. Anticoagulation compliance
analysis showed only about 40% of INR readings to be within target ranges
postoperatively; thus, the control range achieved was much greater than
the desired target, as might generally be expected for clinic-controlled
INR.
Conclusion: The On-X valve performed well in this study, confirming the
original design intent of minimal hemolysis and low adverse event rates.
The Journal of Heart Valve Disease 2006;15:73-79 |