Patient prosthesis mismatch is rare after aortic valve replacement: Valve size may be irrelevant

Division of Cardiovascular Surgery of Sunnybrook and Women's College Health Sciences Centre, Toronto, Ontario, Canada.
The Annals of Thoracic Surgery (Impact Factor: 3.85). 06/2002; 73(6):1822-9; discussion 1829. DOI: 10.1016/S0003-4975(02)03582-8
Source: PubMed


Although small valve size and patient-prosthesis mismatch are both considered to decrease long-term survival, little direct evidence exists to support this hypothesis.
To assess the prevalence of patient-prosthesis mismatch and the influence of small valve size on survival, we prospectively studied 1,129 consecutive patients undergoing aortic valve replacement between 1990 and 2000. Mean and peak gradients and indexed effective orifice area were measured by transthoracic echocardiography postoperatively (3 months to 10 years). Abnormal postoperative gradients were defined as those patients with mean or peak gradient above the 90th percentile (mean gradient > or = 21 or peak gradient > or = 38 mm Hg). Patient-prosthesis mismatch was defined as those patients with indexed effective orifice area below the 10th percentile (< 0.60 cm2/m2).
A multivariable analysis identified internal diameter of the implanted valve as the only independent predictor of abnormal gradients postoperatively. However, there was no significant difference in actuarial survival between normal and abnormal gradient groups (7 years: 91.2% +/- 1.5% versus 95.0% +/- 2.2%; p = 0.48). Freedom from New York Heart Association class III or IV (7 years: 74.5% +/- 3.1% versus 74.6% +/- 6.2%; p = 0.66) and left ventricular mass index were not different between normal and abnormal gradient groups. Patients with and without patient-prosthesis mismatch were similar with respect to postoperative left ventricular mass index, 7-year survival (95.1% +/- 1.3% versus 94.7% +/- 3.0%; p = 0.54), and 7-year freedom from New York Heart Association class III or IV (79.3% +/- 6.6% versus 74.5% +/- 2.5%; p = 0.40). In patients with patient-prosthesis mismatch and abnormal gradients, the majority had prosthesis dysfunction owing to degeneration.
Severe patient-prosthesis mismatch is rare after aortic valve replacement. Patient-prosthesis mismatch, abnormal gradient, and the size of valve implanted do not influence left ventricular mass index or intermediate-term survival.

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    • "There was a mean decrease in LVM of 23% in patients with an IEOA > 0.8 cm 2 m À2 compared with only 4.5% in those with an IEOA 0.8 cm 2 m À2 ( p = 0.0001). In contrast to these results, Hanayama and co-workers [23] found no significant relationship between PPM and regression of LV hypertrophy in a retrospective study. The major finding of our study was that IEOA (i.e., PPM) was associated with lesser regression of LVM after AVR. "
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    ABSTRACT: Clinical outcomes of patients undergoing aortic valve replacement may be influenced by the presence of residual gradients and patient-prosthesis mismatch. The aim of this study was to compare hemodynamic performance and clinical outcomes at 5 years after prospectively randomized porcine versus bovine aortic valve replacement. We also aimed to determine the effects of valve hemodynamics on left ventricular (LV) mass regression. A total of 108 patients undergoing aortic valve replacement were randomized to receive either the Medtronic Mosaic (MM) porcine (n=54) or the Edwards Perimount Magna (EPM) bovine pericardial prosthesis (n=54). Clinical outcomes, mean gradients, effective orifice area and LV mass regression were evaluated at 1 and 5 years after surgery. Follow-up echocardiograms were performed on 106 (98%) and 87 (92%) patients, respectively. Preoperative characteristics were similar between groups. Mean aortic annulus diameter and mean implant size were comparable in both groups. At 1 and 5 years, mean transprosthetic gradients were lower in the EPM group: EPM 10.3±3.4mmHg versus MM 16.3 ± 7.6 mmHg (p<0.0001) and EPM 9.6 ± 3.5 mmHg versus MM 16.8 ± 8.7 mmHg (p<0.0001), respectively. Similarly, indexed effective orifice areas (IEOA) at 1 and 5 years were significantly greater in the EPM group: EPM 1.10 ± 0.22 cm(2)m(-2) versus MM 0.96 ± 0.22 cm(2)m(-2) (p<0.004) and EPM 1.02 ± 0.25 cm(2)m(-2) versus MM 0.76 ± 0.19 cm(2)m(-2) (p<0.0001), respectively. At 5 years, the incidence of patient-prosthesis mismatch (IEOA ≤0.85 cm(2)m(-2)) was significantly lower in the EPM group: EPM 22.9% vs MM 73.9% (p<0.0001). Such differences were similar when analysis was stratified by surgically measured annular size and implant valve size. During the first year after surgery, both groups demonstrated similar regression of LV mass index (MM -26.3 ± 43 gm(2) vs EPM -30.1 ± 36 gm(-2); p=0.8); however, at 5 years, regression of LV mass index was significantly greater in the EPM group: (EPM -47.4 ± 35 gm(-2) vs -4.4 ± 36 gm(-2); p<0.0001). Five-year survival was 79.6 ± 4.1% in the MM group and 94.4 ± 2.2% in the EPM group (p=0.03). Conclusions: At 5 years, the EPM valve was significantly superior to the MM prosthesis with regard to hemodynamic performance, incidence of patient-prosthesis mismatch and regression of LV mass index. The hemodynamic superiority of the EPM prostheses in comparison to MM-prostheses demonstrated at 1 year, increased significantly over time.
    European Journal of Cardio-Thoracic Surgery 12/2010; 39(6):844-52. DOI:10.1016/j.ejcts.2010.11.015 · 3.30 Impact Factor
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    • "The present study found a significant improvement in LV EF, LV mass, and LV dimension after the immediate post-operative echocardiogram, which was usually performed at 1 week post-operatively. It was reported that LV mass and functional recovery was complete at 1 or 1.5 yr, and that pre-operative LV function was related to normalization of the LV mass index (14-17). Despite the present study involving patients with severe LV dysfunction, LV function improved dramatically, with most of this improvement occurring in the first 6 months post-operatively. "
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    ABSTRACT: Little is known regarding long-term survival and changes in systolic function following surgery after the occurrence of a severe left ventricular (LV) dysfunction in patients with severe aortic stenosis. Inclusion criteria were an aortic valve area less than 1 cm(2) and an LV ejection fraction (EF) less than 35%. Between January 1990 and July 2007, 41 (male: 30) patients were identified. The pre-operative mean EF and mean aortic valve area were 26.7+/-6.1% and 0.54+/-0.2 cm(2), respectively. Concomitant coronary artery bypass surgery was performed in 8 patients (19.6%). Immediate post-operative echocardiogram showed to be much improved in LV EF (27.2+/-5.5 vs. 37.4+/-11.3, P<0.001), LV mass index (244.2+/-75.3 vs. 217.5+/-71.6, P=0.006), and diastolic LV internal diameter (62.5+/-9.3 vs. 55.8+/-9.6, P<0.001). Post-operative LV changes were mostly complete by 6 months, and were maintained thereafter. There was one in-hospital mortality (2.4%) and 12 late deaths including one patient diagnosed with malignancy in whom LV function was normal. Multivariate analysis showed pre-operative atrial fibrillation and NYHA FC IV to be significant risk factors for cardiac-related death. Aortic valve replacement in patients with significant aortic stenosis and severe LV dysfunction showed acceptable surgical outcomes. Moreover, LV function improved significantly in many patients.
    Journal of Korean medical science 10/2009; 24(5):812-7. DOI:10.3346/jkms.2009.24.5.812 · 1.27 Impact Factor
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    • "Our results confirm that the reduction of pressure gradient obtained with small functional prosthesis will result in significant LVM regression. However, as reported with other studies [4] [22] [23] [17], we found residual LVH in 50% of studied patients at follow-up. "
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    ABSTRACT: After aortic valve replacement, the effects of a small functional prosthesis on the extent and pattern of regression of left ventricular hypertrophy and on clinical outcomes may be less significant in older patients with low cardiac output requirements. The objective of this study was therefore to determine whether patient-prosthesis mismatch affects left ventricular mass regression in the elderly. The population studied was made up of 88 patients over 65 years of age with pure aortic stenosis who underwent mechanical aortic valve replacement. The effective orifice area index was calculated for each patient on the basis of the projected prosthesis in vivo effective orifice area. It was considered a continuous variable and influence of its entire range of values on the extent of left ventricular mass regression was analyzed in a multivariate prediction model. Even though, in the group with prosthesis-patient mismatch there was a trend for lower postoperative left ventricular mass index (115+/-24 g/m(2) vs 102+/-27 g/m(2), p=0.24) and postoperative peak trans-prosthetic gradients (32+/-9.8 mmHg vs 28.9+/-7.79 mmHg, p=0.35) these differences were not statistically significant. The prevalence of residual left ventricular hypertrophy at follow-up was 50% in the group with patient-prosthesis mismatch and 50% in the group without patient-prosthesis mismatch (p=0.83). In multivariate analysis the only factors associated with indexed left ventricular mass were the follow-up time (p=0.015, r(2)=0.22) and preoperative indexed left ventricular mass (p=0.0012, r(2)=0.11). The major finding of our study is that patient-prosthesis mismatch does not affect left ventricular mass regression in patients older than 65 with pure aortic stenosis who underwent mechanical aortic valve replacement. In older patients with low cardiac output requirements, even a small change in the valve effective orifice area after aortic valve replacement with modern efficient mechanical prosthesis, will result in a marked reduction of pressure gradient and this will be associated with a significant regression of left ventricular mass.
    European Journal of Cardio-Thoracic Surgery 03/2006; 29(2):139-43. DOI:10.1016/j.ejcts.2005.11.007 · 3.30 Impact Factor
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