On-X versus St Jude Medical Mechanical Prosthesis in mitral position: are we moving forward in design technology?

BACKGROUND: Continuous effort is still provided in designing optimal artificial heart valves with better hemodynamic function and reduced thromboembolic potential. The question is do we have moved forward toward this goal or not. METHODS: A prospective, randomized comparative study was done on 360 patients scheduled for elective mitral valve replacement. Patients were grouped into an On-X group (N.=180), who received On-X mechanical valve, and a SJM group (N.=180), who received St Jude mechanical valve. Echocardiographic and clinical assessments were performed for all patients at 6 and 12 months follow-up period. RESULTS: Rheumatic heart disease was the most common cause of valve affection (94.2%). Early mortality was 6.4%. The mean follow-up time was 3.11±2.44 years. No structural or non-structural valvular dysfunction and no thromboembolism cases were encountered. Late valve thrombosis was1.9%/patient-year in On-X group and 2.1%/patient-year in SJM group. The mean EOA was higher in On-X group (2.0±0.3 cm2) than in SJM group (1.9±0.2 cm2), (P≥0.05). The mean EOAI was higher in On-X group (1.1±0.1 cm2/m2) than in SJM group (1.0±0.1 cm2/m2), (P=0.034), especially significant in small valve size (25 mm) where it was 1.09±021 cm2/m2 in On-X group and 0.93±0.12 cm2/m2 in SJM group (P=0.02). CONCLUSIONS: On-X and St Jude prosthetic valves have a comparable hemodynamic performance in mitral position. However, On-X prosthesis might have a forward step on the way of design technology that may allow better function in terms of EOA and EOAI especially in smaller valve size.

Economic Evaluation of the Combined Use of Warfarin and Low-dose Aspirin Versus Warfarin Alone in Mechanical Valve Prostheses.

BACKGROUND: The use of combined therapy of antiplatelet and anticoagulant versus anticoagulant alone to reduce instances of thromboembolic events in patients with heart valve prostheses is an established standard of care in many countries but not in Egypt. A previous Markov model cost-effectiveness study on Egyptian patients aged 50-60 years demonstrated that the combined therapy reduces the overall treatment cost. However, due to the lack of actual real-world data on cost-effectiveness and the limitation of the Markov model study to 50- to 60-year-old patients, the Egyptian medical community is still questioning whether the added benefit is worth the cost. OBJECTIVE: To assess, from the perspective of the Egyptian health sector, the cost-effectiveness of the combined use of warfarin and low-dose aspirin (75 mg) versus that of warfarin alone in patients with mechanical heart valve prostheses who began therapy between the age of 15 and 50 years. METHODS: An economic evaluation was conducted alongside a randomized, controlled trial to assess the cost-effectiveness of the combined therapy in patients with mechanical valve prostheses. A total of 316 patients aged between 15 and 50 years were included in the study and randomly assigned to a group treated with both warfarin and aspirin or a group treated with warfarin alone. RESULTS: The patients in the combined therapy group exhibited a significantly longer duration of protection against the first event. Fewer primary events were observed in the patients treated with warfarin plus aspirin than in those treated with warfarin alone (1.4 %/year, vs. 4.8 %/year), and a higher mean quality-adjusted life-years (QALYs) value over 4 years was obtained for the group treated with warfarin plus aspirin (difference 0.058; 95 % CI 0.013-0.118), although this difference did not reach a conventional level of statistical significance. The total costs over a 4-year period were lower with the combined therapy (difference -US$244; 95 % CI -US$483.1 to -US$3.8), which yielded an incremental cost-effectiveness ratio of -US$4206 per QALY gained. Thus, the combined therapy was dominant. All costs were reported in US dollars (USD) for the financial year 2014. CONCLUSIONS: The results of this analysis indicate that from the perspective of the Egyptian health sector, the addition of aspirin to the typical warfarin therapy is more effective and less costly for patients with mechanical valve prostheses than treatment with warfarin alone. This combined strategy could be adopted to prevent the complications of mechanical valve prostheses. Our study adds to the body of evidence supporting the option of warfarin-plus-aspirin therapy for patients with mechanical valve prostheses.

Cost-Effectiveness of the Combined Use of Warfarin and Low-Dose Aspirin versus Warfarin Alone in Egyptian Patients with Aortic Valve Replacements: A Markov Model.

BACKGROUND: The combination of antiplatelet and anticoagulant therapy significantly reduces the rate of thromboembolic events in patients with heart valves compared with anticoagulant therapy alone. Cost-effectiveness of this therapy in Egypt, however, has not yet been established. OBJECTIVE: The aim of the present study was to evaluate the cost-effectiveness of the combined use of warfarin and low-dose aspirin (100 mg) versus warfarin alone in patients with mechanical aortic heart valve prostheses who began therapy at the age of 50 to 60 years over a 5-year period from the perspective of the medical providers. METHODS: A cohort Markov process model with five health states (recovery, reoperation, bleeding, thromboembolism, and death) based on Egyptian clinical practice was derived from published sources. The clinical parameters were derived from meta-analyses of randomized controlled trials of patients with mechanical valve prostheses. The quality of life of the health states was derived using the available published data. Direct medical costs were obtained from four top-rated governmental cardiology hospitals in Egypt. All costs and effects were discounted at 3.5% annually. All costs were converted using the purchasing power parity rate and are reported in US $ for the financial year of 2013. RESULTS: The total quality-adjusted life-years (QALYs) were estimated to be 1.1616 and 1.1199 for the warfarin plus aspirin group and the warfarin group, respectively, which resulted in a difference of 0.0416 QALYs. The total costs for the warfarin plus aspirin group and the warfarin group were US $307.33 and US $315.25, respectively (the difference was US $7.92), which yielded an incremental cost-effectiveness ratio of -190.38 for the warfarin plus aspirin group. Thus, the combined therapy was dominant. Various one-way sensitivity analyses indicated that probabilities of reoperation and bleeding in the recovery state had the greatest effects on incremental costs. The model parameters that had the greatest effects on incremental QALYs were the relative risk reduction of death and the utility value in the recovery state. CONCLUSIONS: The present study is the first cost-utility analysis to conclude that, from the perspective of Egyptian medical providers, combined therapy is more effective and less costly than warfarin alone for patients with mechanical aortic valve prostheses. For clinicians and patients who choose to focus on minimizing thromboembolic risk, these results suggest that combined therapy offers the best protection. This study helps to inform decisions about the allocation of health care system resources and to achieve better health in the Egyptian population.