Original article
Adult cardiac
Effect of Prosthesis-Patient Mismatch on Long-Term Survival With Mitral Valve Replacement: Assessment to 15 Years

Presented at the Forty-fourth Annual Meeting of The Society of Thoracic Surgeons, Fort Lauderdale, FL, Jan 28–30, 2008.
https://doi.org/10.1016/j.athoracsur.2009.01.056Get rights and content

Background

The effect of prosthesis-patient mismatch on long-term survival after mitral valve replacement (MVR) has received limited attention. This study was performed to determine the predictors of mortality after MVR and influence of prosthesis-patient mismatch on survival.

Methods

Contemporary mechanical prostheses and bioprostheses were implanted in 2,440 patients with MVR between 1982 and 2002. The mean age was 63.9 ± 12.1 years and the mean follow-up was 6.1 ± 4.6 years, a total of 14,797.7 years of follow-up. Prosthesis-patient mismatch was classified by effective orifice area index categories: normal, greater than 1.2 cm2/m2 (345, 14.2%); mild-to-moderate, equal to or less than 1.2 to greater than 0.9 cm2/m2 (1,696, 69.5%); and severe, equal to or less than 0.9 cm2/m2 (399, 16.4%).

Results

The predictors of overall mortality were age, age categorization, New York Heart Association III-IV, concomitant coronary artery bypass, ventricular dysfunction, prosthesis type, body mass index, and pulmonary hypertension. All categories of effective orifice area indices (EOAIs) were not predictive of overall mortality, late mortality, or early mortality. The 15-year survival was not differentiated by EOAI categories; 32.0 ± 4.4%, 32.9 ± 2.1%, and 36.6 ± 6.3%, respectively, for the three categories. Pulmonary hypertension influenced mortality by EOAI categories; normal versus mild-to-moderate (p = 0.0317) and normal versus severe (p = 0.0320). The EOAI was not an independent predictor of mortality in the consideration of patients with pulmonary hypertension but there is an interaction between pulmonary hypertension and mild-to-moderate (p = 0.023) and severe (p = 0.031) EOAI.

Conclusion

Prosthesis-patient mismatch is not a predictor of overall mortality to 15 years after MVR regardless of the category of effective orifice area index. The preoperative variable, pulmonary hypertension, influences overall mortality in the presence of mild-to-moderate and severe prosthesis-patient mismatch in the survival analysis.

Section snippets

Patients and Methods

This is a retrospective study of prospectively collected data from the University of British Columbia Cardiac Valve Database. The database receives annual renewal from the University of British Columbia Clinical Research Ethics Board, which has a formal informed consenting process of patients.

From 1982 to 2002, 2,440 patients had MVRs at the affiliated teaching hospitals (St. Paul's Hospital, Vancouver General Hospital and Royal Columbian Hospital) of the University of British Columbia. There

Results

Of the total population of 2,440 patients, 345 (14.1%) had nonsignificant PPM, 1,696 (69.5%) had mild-to-moderate PPM, and 399 (16.4%) had severe PPM. The mean follow-up was 6.1 ± 4.6 years (median 5.9 years). During follow-up, 933 (38.2%) died: early mortality 159 (6.5%) (BP 8.6%, MP 3.9%; p ω 0.0001); late mortality 744 (31.7%); cardiac-related mortality 452 (18.5%); and valve-related mortality 168 (6.9%). The early mortality for nonsignificant-normal patients (PPM-A) was 5.5%,

Comment

This study identified the risk factors for mortality after MVR, considering specifically effective orifice area index categories. The significant findings of the study are related to the total lack of long-term survival influence to 12 to 15 years in all the modeling of mortality, inclusive of mild-to-moderate prosthesis-patient mismatch and severe prosthesis-patient mismatch. The interest in prosthesis-patient mismatch with valve replacement has only been documented since 2004 [15, 16, 17, 20

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