North American multicenter experience with the On-X prosthetic heart valve.
OBJECTIVE
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.


CONCLUSIONS
The On-X valve performed well in this study, confirming the original design intent of minimal hemolysis and low adverse event rates.
Christiana Care Health System, Newark, DE, USA.
Kathleen W
KW
McNicholas
Tom D
TD
Ivey
Jacques
J
Metras
Szabolcs
S
Szentpetery
Steven W
SW
Marra
Roy G
RG
Masters
Emery W
EW
Dilling
Mark S
MS
Slaughter
Michael J
MJ
Mack
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000008:administration & dosage; D001021:Aortic Valve / Q000601:surgery*; D015415:Biomarkers / Q000097:blood; D004869:Equipment Safety; D005260:Female; D005500:Follow-Up Studies; D006349:Heart Valve Diseases / Q000601:surgery*; D006350:Heart Valve Prosthesis / Q000009:adverse effects; D019918:Heart Valve Prosthesis Implantation / Q000009:adverse effects; D006801:Humans; D019934:International Normalized Ratio; D008297:Male; D008875:Middle Aged; D008943:Mitral Valve / Q000601:surgery*; D009656:North America / Q000453:epidemiology; D010349:Patient Compliance; D011446:Prospective Studies; D011474:Prosthesis Design; D016896:Treatment Outcome
D000925:Anticoagulants; D015415:Biomarkers