Mechanical Versus Bioprosthetic Aortic Valve Replacement in Middle-Aged Adults: A Systematic Review and Meta-Analysis

Zhao DF, Seco M, Wu JJ, Edelman JB, Wilson MK, Vallely MP, Byrom MJ, Bannon PG

Ann. Thorac. Surg. 2016 Jan;

PMID: 26794881

Abstract

The choice of a bioprosthetic valve (BV) or mechanical valve (MV) in middle-aged adults undergoing aortic valve replacement is a complex decision that must account for numerous prosthesis and patient factors. A systematic review and meta-analysis was performed to compare long-term survival, major adverse prosthesis-related events, anticoagulant-related events, major bleeding, reoperation, and structural valve degeneration in middle-aged patients receiving a BV or MV. A comprehensive search from six electronic databases was performed from their inception to February 2016. Results from patients aged less than 70 years undergoing aortic valve replacement with a BV or MV were included. There were 12 studies involving 8,661 patients. Baseline characteristics were similar. There was no significant difference in long-term survival among patients aged 50 to 70 or 60 to 70 years. Compared with MVs, BVs had significantly fewer long-term anticoagulant-related events (hazard ratio [HR] 0.54, p = 0.006) and bleeding (HR 0.48, p < 0.00001) but significantly greater major adverse prosthesis-related events (HR 1.82, p = 0.02), including reoperation (HR 2.19, p < 0.00001). The present meta-analysis found no significant difference in survival between BVs and MVs in patients aged 50 to 70 or 60 to 70 years. Compared with MVs, BVs have reduced risk of major bleeding and anticoagulant-related events but increased risk of structural valve degeneration and reoperation. However, the mortality consequences of reoperation appear lower than that of major bleeding, and recent advances may further lower the reoperation rate for BV. Therefore, this review supports the current trend of using BVs in patients more than 60 years of age.

Nonsyndromic Thoracic Aortic Aneurysm and Dissection: Outcomes With Marfan Syndrome Versus Bicuspid Aortic Valve Aneurysm

Sherrah AG, Andvik S, van der Linde D, Davies L, Bannon PG, Padang R, Vallely MP, Wilson MK, Keech AC, Jeremy RW

J. Am. Coll. Cardiol. 2016 Feb;67(6):618-26

PMID: 26868685

Abstract

BACKGROUND: Genetic aortopathy (GA) underlies thoracic aortic aneurysms (TAA) in younger adults. Comparative survival and predictors of outcomes in nonsyndromic TAA (NS-TAA) are incompletely defined compared to Marfan syndrome (MFS) and bicuspid aortic valve (BAV).

OBJECTIVES: The study sought to compare survival and clinical outcomes for individuals with NS-TAA, MFS, and BAV.

METHODS: From 1988 to 2014, all patients presenting with GA 16 to 60 years of age were enrolled in a prospective study of clinical outcomes. Risk factors for death and aortic dissection were identified by Cox proportional hazards modeling and a mortality risk score developed.

RESULTS: Diagnosis of GA was made for 760 patients (age 36.9 ± 13.6 years, 26.8% female; NS-TAA, n = 311; MFS, n = 221; BAV, n = 228). MFS patients were younger than NS-TAA and BAV. Presentation with aortic dissection was more common for NS-TAA than MFS or BAV. The 687 patients surviving >30 days after presentation were followed for a median of 7 years. Calculated 10-year mortality was 7.8% for NS-TAA, 8.7% for MFS, and 3.5% for BAV (NS-TAA and MFS vs. BAV p <0.05). Factors associated with all-cause mortality were MFS (p = 0.04), age at presentation, and family history of dissection.

CONCLUSIONS: Clinical outcomes for MFS and NS-TAA are similar but worse than BAV. Independent predictors of mortality, including family history of aortic dissection and age, can be included in an Aortopathy Mortality Risk Score to predict survival. Management of NS-TAA, including surgical intervention, should be similar to that of MFS.

MRI in Chronic Aortic Dissection: A Systematic Review and Future Directions

Sherrah AG, Grieve SM, Jeremy RW, Bannon PG, Vallely MP, Puranik R

Front Cardiovasc Med 2015;2:5

PMID: 26664877

Abstract

The acute event of thoracic aortic dissection carries with it high mortality and morbidity. Despite optimal initial surgical or medical management strategies, the risk of further complications in the long-term, including aneurysmal dilatation and false lumen (FL) expansion, are not insignificant. Adequate follow-up of such conditions requires dedicated imaging where relevant prognostic indicators are accurately assessed. We perform a systematic review of the literature and report the current evidence for the use of magnetic resonance imaging (MRI) in assessment of chronic aortic dissection. We then make a comparison with traditional imaging modalities including computed tomography and echocardiography. We discuss new ways in which MRI may extend existing aortic assessment, including identification of blood-flow dynamics within the TL and FL using phase-contrast imaging.

Long Term Outcomes Following Freestyle Stentless Aortic Bioprosthesis Implantation: An Australian Experience

Sherrah AG, Jeremy RW, Puranik R, Bannon PG, Hendel PN, Bayfield MS, Wilson MK, Brady PW, Marshman D, Mathur MN, Brereton RJ, Edwards JR, Stuklis RG, Worthington M, Vallely MP

Heart Lung Circ 2015 Jun;

PMID: 26146198

Abstract

BACKGROUND: The Freestyle stentless bioprosthesis (FSB) has been demonstrated to be a durable prosthesis in the aortic position. We present data following Freestyle implantation for up to 10 years post-operatively and compare this with previously published results.

METHODS: A retrospective cohort analysis of 237 patients following FSB implantation occurred at five Australian hospitals. Follow-up data included clinical and echocardiographic outcomes.

RESULTS: The cohort was 81.4% male with age 63.2±13.0 years and was followed for a mean of 2.4±2.3 years (range 0-10.9 years, total 569 patient-years). The FSB was implanted as a full aortic root replacement in 87.8% patients. The 30-day all cause mortality was 4.2% (2.0% for elective surgery). Cumulative survival at one, five and 10 years was 91.7±1.9%, 82.8±3.8% and 56.5±10.5%, respectively. Freedom from re-intervention at one, five and 10 years was 99.5±0.5%, 91.6±3.7% and 72.3±10.5%, respectively. At latest echocardiographic review (mean 2.3±2.1 years post-operatively), 92.6% had trivial or no aortic regurgitation. Predictors of post-operative mortality included active endocarditis, acute aortic dissection and peripheral vascular disease.

CONCLUSIONS: We report acceptable short and long term outcomes following FSB implantation in a cohort of comparatively younger patients with thoracic aortic disease. The durability of this bioprosthesis in the younger population remains to be confirmed.

Use of multi-velocity encoding 4D flow MRI to improve quantification of flow patterns in the aorta

Callaghan FM, Kozor R, Sherrah AG, Vallely M, Celermajer D, Figtree GA, Grieve SM

J Magn Reson Imaging 2015 Jun;

PMID: 26130421

Abstract

PURPOSE: To show that the use of a multi-velocity encoding (VENC) 4D-flow approach offers significant improvements in the characterization of complex flow in the aorta. Four-dimensional flow magnetic resonance imaging (MRI) (4D-flow) can be used to measure complex flow patterns and dynamics in the heart and major vessels. The quality of the information derived from these measures is dependent on the accuracy of the vector field, which is limited by the vector-to-noise ratio.

MATERIALS AND METHODS: A 4D-flow protocol involving three different VENC values of 150, 60, and 20 cm/s was performed on six control subjects and nine patients with type-B chronic aortic dissection at 3T MRI. Data were processed using a single VENC value (150 cm/s) or using a fused dataset that selected the lowest appropriate VENC for each voxel. Performance was analyzed by measuring spatial vector angular correlation, magnitude correlation, temporal vector conservation, and “real-world” streamline tracing performance.

RESULTS: The multi-VENC approach provided a 31% improvement in spatial and 53% improvement in temporal precision of velocity vector measurements during the mid-late diastolic period, where 99% of the flow vectors in the normal aorta are below 20 cm/s. In low-flow conditions this resulted in practical improvements of greater than 50% in pathline tracking and streamline tracing quantified by streamline curvature measurements.

CONCLUSION: A multi-VENC 4D-flow approach provides accurate vector data across normal physiological velocities observed in the aorta, dramatically improving outputs such as pathline tracking, streamline estimation, and further advanced analyses.J. Magn. Reson. Imaging 2015.

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