Impact of Prosthesis–Patient Size on Functional Recovery After Aortic Valve Replacement

Impact of Prosthesis-Patient Mismatch on Survival After Mitral Valve Replacement

Background— We recently reported that valve prosthesis-patient mismatch (PPM) is associated with persisting pulmonary hypertension after mitral valve replacement. Thus, the objective of this study was to evaluate the impact of PPM on mortality in patients undergoing mitral valve replacement.

Methods and Results— The indexed valve effective orifice area was estimated for each type and size of prosthesis being implanted in 929 consecutive patients and used to define PPM as not clinically significant if >1.2 cm 2 /m 2 , as moderate if >0.9 and ≤1.2 cm 2 /m 2 , and as severe if ≤0.9 cm 2 /m 2 . Moderate PPM was present in 69% of patients; severe PPM was seen in 9%. For patients with severe PPM, 6-year survival (74±5%) and 12-year survival (63±7%) were significantly less than for patients with moderate PPM (84±1% and 76±2%; P =0.027) or nonsignificant PPM (90±2% and 82±4%; P =0.002). On multivariate analysis, severe PPM was associated with higher mortality (hazard ratio, 3.2; 95% confidence interval, 1.5 to 6.8; P =0.003).

Conclusions— Severe PPM is an independent predictor of mortality after mitral valve replacement. As opposed to other independent risk factors, PPM may be avoided or its severity may be reduced with the use of a prospective strategy at the time of operation. For patients identified as being at risk for severe PPM, every effort should be made to implant a prosthesis with a larger effective orifice area.

Prediction of valve prosthesis-patient mismatch prior to aortic valve replacement: which is the best method?

BACKGROUND

To predict the occurrence of valve prosthesis-patient mismatch (VP-PM) after aortic valve replacement (AVR), the surgeon needs to estimate the postoperative effective orifice area index (EOAI).

AIM

To compare different methods of predicting VP-PM.

METHODS

The effective orifice area (EOA) of 383 patients who had undergone AVR between July 2000 and January 2005 with various aortic valve prostheses was obtained echocardiographically 6 months after the operation. We tested the efficacy of (1) EOAI calculated from the echo data obtained in our own laboratory, (2) indexed geometric orifice area, (3) EOAI estimated from charts provided by prosthesis manufacturers (which are based either on in vitro or on echo data) and (4) EOAI estimated from reference echo data published in the literature to predict VP-PM.

RESULTS

Sensitivity and specificity to predict VP-PM were 53% and 83% (method 1), 80% and 53% (charts based on echo data, parts of method 3) and 71% and 67% (method 4) using reference data derived from echocardiographic examinations. The sensitivity of method 2 and of charts based on in vitro data (parts of method 3) to predict VP-PM was 0-17%. The incidence of severe VP-PM could be reduced from 8.7% to 0.8% after the introduction of the systematic estimation of the EOAI at the time of operation (p = 0.003, method 1).

CONCLUSIONS

The best method of predicting VP-PM is the use of mean (SD) EOAs derived from echocardiographic examinations, whereas the use of in vitro data or the geometric orifice area is unreliable. After the surgeon's anticipation of VP-PM prior to AVR, the incidence of VP-PM could be reduced.

Small aortic annulus: The hydrodynamic performances of 5 commercially available tissue valves

BACKGROUND

In vivo comparison of the performance of heart valve prostheses is confounded by several factors, such as different nominal size, patients' characteristics and hemodynamics, surgical techniques, and study design. The aim of this study was to compare the in vitro hydrodynamic performances of 5 different tissue valves that would fit a 21-mm-diameter valve holder of the Sheffield pulse duplicator.

METHODS

Three samples of 5 supra-annular production-quality tissue valves, including the sewing ring cuffs, were tested in the aortic chamber of the Sheffield pulse duplicator. The prostheses fitting a 21-mm valve holder, which is comparable with a 21-mm aortic annulus, were as follows: 20-mm Sorin Soprano, 21-mm Carpentier-Edwards Magna, 21-mm SJM-Biocor-Epic-Supra, 21-mm Medtronic Mosaic, and 23-mm Mitroflow. The tests were carried out at a fixed pulse rate (70 beats/min) and at increasing cardiac outputs of 2, 4, 5, and 7 L/min. Each valve was tested 10 times for each different cardiac output. This resulted in a total of 40 tests for each valve and 120 tests for each valve model. Forward flow pressure decrease, effective orifice area, stroke work loss, and total regurgitant, closing, and leakage volumes were recorded while the valve operated under each cardiac output.

RESULTS

Pericardial valves showed significantly lower transvalvular gradients than porcine valves, unlike the SJM-Biocor-Epic-Supra valve at 2 L/min of cardiac output. Although the Carpentier-Edwards Magna valve provided the best performance at 2 and 4 L/min, the Mitroflow valve exhibited the lowest mean and peak gradients at 5 to 7 L/min. Total regurgitant and leakage volumes were higher for the Carpentier-Edwards Magna valve and lower for the SJM-Biocor-Epic-Supra and Mitroflow valves. Between 2 and 4 L/min, the calculated effective orifice area and stroke work loss were better for the Carpentier-Edwards Magna valve, whereas between 5 and 7 L/min, they were significantly superior with the Mitroflow prosthesis. Among the porcine bioprostheses, the SJM-Biocor-Epic-Supra valve showed significantly better results when compared with the Medtronic Mosaic valve at each cardiac output.

CONCLUSION

Assuming that the valve holder is comparable with a defined aortic annulus of 21 mm in which a spread of supra-annular tissue valves could be fitted, this hydrodynamic evaluation model allows comparison of the efficiency of currently available bioprostheses with a definite tissue annulus diameter. Pericardial valves exhibited the best performances, and the Mitroflow valve showed the lowest gradients and stroke work loss at increasing cardiac output.

Impact of Prosthesis-Patient Mismatch on Cardiac Events and Midterm Mortality After Aortic Valve Replacement in Patients With Pure Aortic Stenosis

Background— Prosthesis-patient mismatch (PPM) occurs when the effective orifice area (EOA) of the prosthesis being implanted is too small in relation to body size, thus causing abnormally high transvalvular pressure gradients. The objective of this study was to examine the midterm impact of PPM on overall mortality and cardiac events after aortic valve replacement in patients with pure aortic stenosis.

Methods and Results— The indexed EOA (EOAi) was estimated for each type and size of prosthesis being implanted in 315 consecutive patients with pure aortic stenosis. PPM was defined as an EOAi ≤0.80 cm 2 /m 2 and was correlated with overall mortality and cardiac events. PPM was present in 47% of patients. The 5-year overall survival and cardiac event-free survival were 82±3% and 75±4%, respectively, in patients with PPM compared with 93±3% and 87±4% in patients with no PPM ( P ≤0.01). In multivariate analysis, PPM was associated with a 4.2-fold (95% CI, 1.6 to 11.3) increase in the risk of overall mortality and 3.2-fold (95% CI, 1.5 to 6.8) increase in the risk of cardiac events. The other independent risk factors were history of heart failure, NHYA class III-IV, severe left ventricular hypertrophy, and absence of normal sinus rhythm before operation.

Conclusions— PPM is an independent predictor of cardiac events and midterm mortality in patients with pure aortic stenosis undergoing aortic valve replacement. As opposed to other risk factors, PPM may be avoided or its severity may be reduced with the use of a preventive strategy at the time of operation.

Prosthesis-patient mismatch: definition, clinical impact, and prevention

Prosthesis-patient mismatch (PPM) is present when the effective orifice area of the inserted prosthetic valve is too small in relation to body size. Its main haemodynamic consequence is to generate higher than expected gradients through normally functioning prosthetic valves. This review updates the present knowledge about the impact of PPM on clinical outcomes. PPM is common (20-70% of aortic valve replacements) and has been shown to be associated with worse haemodynamic function, less regression of left ventricular hypertrophy, more cardiac events, and lower survival. Moreover, as opposed to most other risk factors, PPM can largely be prevented by using a prospective strategy at the time of operation.