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.