Outcome of reoperation for aortic valve prosthesis-patient mismatch

Imaging for Predicting and Assessing Prosthesis-Patient Mismatch After Aortic Valve Replacement

Prosthesis-patient mismatch (PPM) occurs when the effective orifice area (EOA) of the prosthetic valve is too small in relation to a patient's body size, thus resulting in high residual postoperative pressure gradients across the prosthesis. Severe PPM occurs in 2% to 20% of patients undergoing surgical aortic valve replacement (AVR) and is associated with 1.5- to 2.0-fold increase in the risk of mortality and heart failure rehospitalization. The purpose of this article is to present an overview of the role of multimodality imaging in the assessment, prediction, prevention, and management of PPM following AVR. The risk of PPM can be anticipated at the time of AVR by calculating the predicted indexed from the normal reference value of EOA of the selected prosthesis and patient's body surface area. The strategies to prevent PPM at the time of surgical AVR include: 1) implanting a newer generation of prosthetic valve with better hemodynamic; 2) enlarging the aortic root or annulus to accommodate a larger prosthetic valve; or 3) performing TAVR rather than surgical AVR. The identification and quantitation of PPM as well as its distinction versus prosthetic valve stenosis is primarily based on transthoracic echocardiography, but important information may be obtained from other imaging modalities such as transesophageal echocardiography and multidetector computed tomography. PPM is characterized by high transprosthetic velocity and gradients, normal EOA, small indexed EOA, and normal leaflet morphology and mobility. Transesophageal echocardiography and multidetector computed tomography are particularly helpful to assess prosthetic valve leaflet morphology and mobility, which is a cornerstone of the differential diagnosis between PPM and pathologic valve obstruction. Severe symptomatic PPM following AVR with a bioprosthetic valve may be treated by redo surgery or the transcatheter valve-in-valve procedure with fracturing of the surgical valve stent.

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.

Impact of Prosthesis-Patient Mismatch on Long-Term Survival in Patients With Small St Jude Medical Mechanical Prostheses in the Aortic Position

Background— The impact of aortic prosthesis-patient mismatch (P-PtM) on long-term survival is unclear.

Methods and Results— Between 1985 and 2000, 388 patients at Mayo Clinic in Rochester, Minn, underwent aortic valve replacement (AVR) with 19- or 21-mm St Jude Medical prostheses and had transthoracic echocardiography within 1 year after AVR. Mean age of patients was 62±13 years; 69% were female. Prosthesis effective orifice area (EOA) was derived from the continuity equation. P-PtM was classified as severe (indexed EOA ≤0.60 cm 2 /m 2 ), moderate (0.60 cm 2 /m 2 <indexed EOA≤0.85 cm 2 /m 2 ), or not hemodynamically significant (indexed EOA >0.85 cm 2 /m 2 ). P-PtM was severe in 66 patients (17%), moderate in 168 (43%), and not hemodynamically significant in 154 (40%). Patients with severe P-PtM had a significantly larger body surface area ( P <0.0001), higher mean gradient ( P <0.0001), lower preoperative ( P <0.0001) and postoperative ( P <0.0001) ejection fractions, and lower stroke volume ( P <0.0001) and more often received a 19-mm prosthesis ( P =0.0008) than patients with moderate or no hemodynamically significant mismatch. For patients with severe mismatch, 5-year survival rates (72±6%) and 8-year survival rates (41±8%) were significantly less than for patients with moderate mismatch (80±3% and 65±5%; P =0.026) or no hemodynamically significant mismatch (85±3% and 74±5%; P =0.002). On multivariate analysis after adjustment for other predictors of outcome, severe mismatch was associated with higher mortality (hazard ratio 2.18; 95% confidence interval 1.24 to 3.85; P =0.007) and higher incidence of congestive heart failure (hazard ratio 3.1; 95% confidence interval 1.3 to 7.4; P =0.009) than no hemodynamically significant mismatch.

Conclusions— Severe P-PtM is an independent predictor of higher long-term mortality and congestive heart failure in patients with small St Jude Medical aortic valve prostheses. For patients undergoing AVR who are at risk of severe mismatch, every effort should be made to use a larger prosthesis or to consider a prosthesis with a larger EOA.

Usefulness of the Cryolife O'Brien stentless suprannular aortic valve to prevent prosthesis-patient mismatch in the small aortic root

OBJECTIVES

This study evaluated the occurrence of prosthesis-patient mismatch (PPM) after Cryolife O'Brien (CLOB) suprannular stentless valve replacement in patients with a small aortic root and its repercussions on the patient's hemodynamic status and left ventricular mass regression.

BACKGROUND

The correct management of the small aortic annulus is still controversial. Small aortic prostheses can lead to a PPM, which results in high gradients with important repercussions on the hemodynamic status.

METHODS

Seventy-two patients (mean age: 72.5 +/- 6.2 years, 73.6% women) with a small aortic root (< or =21 mm intraoperatively measured aortic annulus) had a CLOB valve implanted in the aortic position between November 1993 and July 2001 at our institution. Mean prosthesis size was 22.0 +/- 0.8 mm. Patients underwent echocardiography preoperatively, at discharge, six months, one year and yearly thereafter.

RESULTS

The incidence of PPM at discharge was 22.2% (16/72); 18.7% were severe (effective orifice area index [EOAI] < or =0.65 cm/m(2)), 43.7% were moderate (EOAI = 0.66 to 0.75 cm/m(2)) and 37.6% were mild (0.76 to 0.85 cm/m(2)). At multivariable analysis, gender (p < 0.001), age (p = 0.015), body surface area (p < 0.001) and patient's annulus index (p < 0.001) were significant factors influencing the occurrence of "transient" PPM. At one year the incidence of PPM was 0%. CONCLUSIONS; Suprannular CLOB valve yielded excellent hemodynamic results in patients with small aortic roots. This study demonstrates that PPM can be completely avoided when using the CLOB valve. The superior hemodynamics of this stentless valve are likely to be related to its suprannular design.

Preliminary experience with the St. Jude Medical Regent mechanical heart valve in the aortic position: early in vivo hemodynamic results

BACKGROUND

The St. Jude Medical Regent is a new generation mechanical aortic valve.

METHODS

Between March 2000 and July 2001, this valve was implanted in the aortic position in 40 patients (21 men; mean age 59.1 +/- 9.0 years). Preoperatively, 24 patients (60%) were in New York Heart Association functional class III or IV. Eighteen patients (45%) underwent associated procedures. Mean valve size was 21.4 +/- 2.4 mm. The mean duration of follow-up was 8.5 +/- 4.5 months (range, 1 to 16 months).

RESULTS

There were no operative deaths. Early complications included one reoperation for bleeding and one transient low output syndrome. Valve replacement was followed by a significant reduction in mean and peak transaortic gradients over time (p < 0.001) and analysis of variance failed to demonstrate statistical differences between valve size over time (p = not significant). A significant reduction in left ventricular hypertrophy occurred over time (p = 0.01) in all valve sizes (p = not significant between groups): baseline left ventricular mass index was 194 g/cm2; it reduced by 22 g/cm2 (p = 0.006) at discharge. Left ventricular mass index decreased from 172 +/- 55 g/cm2 to 156 +/- 44 g/cm2 (p = 0.03) from discharge to 2 months. Further reductions were not significant. Relative wall thickness decreased from 0.57 +/- 0.13 preoperatively to 0.42 +/- 0.06 at discharge (p = 0.001), and again at 2 months (-0.2; p = not significant), and at 1 year (-0.02; p = not significant).

CONCLUSIONS

The early experience with the St. Jude Medical Regent valve has been satisfactory.