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Determinants of Bioprosthetic Aortic Valve Degeneration
Study Questions:
What is the incidence and mechanism of valve hemodynamic deterioration (VHD) in bioprosthetic aortic valves?
Methods:
A total of 466 consecutive patients were enrolled, all of whom had surgical bioprosthetic aortic valve replacements (AVRs) done between 1994 and 2009 at a university-affiliated hospital in Vienna. They were followed prospectively with clinical assessment, transthoracic echocardiography (TTE), and laboratory testing every 1-2 years. Clinically relevant VHD was based on a TTE-derived, mean transprosthetic gradient ≥30 mm Hg and/or at least moderate regurgitation. Patient-prosthesis mismatch (PPM) was defined as an effective orifice area indexed to body surface area ≤0.8 cm2/m2.
Results:
Median follow-up was 113 months (interquartile range [IQR], 57-148 months) during which time 383 (82%) patients had echocardiographic and laboratory data available. Clinically relevant VHD developed in 70 patients (18%, 4.8% per valve-year) after a median delay of 32 months (IQR, 13-87 months). Modes of the VHD consisted of stenosis (n = 45), regurgitation (n = 16), or both (n = 9). Baseline clinical parameters and echocardiographic data in the VHD and no VHD groups were similar except for the VHD group having more porcine tissue valves than the no VHD group (53% vs. 31%, p < 0.001).
Multivariate regression analysis showed that parameters associated with VHD were serum creatinine >2.1 mg/dl (HR, 4.1; 95% CI, 1.7-9.9; p = 0.001), porcine tissue valves (HR, 2.24; 95% CI, 1.4-3.7; p = 0.002), hypertension (HR, 3.02; 95% CI, 1.4-6.4; p = 0.0040), and PPM (HR, 1.9; 95% CI, 1.1-3.8; p = 0.022). VHD rates varied according to age: 2.0% vs. 4.7% vs. 5.4% per valve-year in patients <70 years, 70-80 years, and >80 years, respectively.
Conclusions:
Clinically relevant VHD after bioprosthetic AVR was seen in 18% of patients, and was associated with use of porcine tissue valves, higher creatinine, hypertension, and PPM. Patients >70 years had shorter event-free survival and faster rates of VHD.
Perspective:
Use of bioprosthetic aortic valves in a younger population has been increasing, in part due to the extended durability of the newer bioprostheses as well as the possibility to perform percutaneous valve-in-valve procedures when these valves do degenerate. This practice would seem to be supported by this study, the first to provide long-term data on factors associated with VHD. Determinants of developing VHD were porcine tissue, renal impairment, arterial hypertension, and PPM. In contrast to previous studies, in which younger age was associated with faster rates of VHD, this study showed a slower rate of valve degeneration in those <70 years of age. Future studies will need to confirm these results in order to justify the increased use of tissue valves in younger patients. Amongst the other risk factors identified in this study, use of porcine valves stands out as somewhat unexpected. The authors postulate that porcine valves may be more immunogenic than their bovine counterparts.
Clinical Topics: Cardiac Surgery, Geriatric Cardiology, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Prevention, Valvular Heart Disease, Aortic Surgery, Cardiac Surgery and VHD, Interventions and Imaging, Interventions and Structural Heart Disease, Echocardiography/Ultrasound, Hypertension
Keywords: Aortic Valve Insufficiency, Artificial Limbs, Bioprosthesis, Body Surface Area, Cardiac Surgical Procedures, Constriction, Pathologic, Creatinine, Diagnostic Imaging, Echocardiography, Geriatrics, Heart Valve Diseases, Heart Valve Prosthesis, Hemodynamics, Hypertension, Risk Factors, Transcatheter Aortic Valve Replacement
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