Limitations in the Assessment of Prosthesis-Patient Mismatch

Patient Prosthesis Mismatch After SAVR and TAVR

Patient-prosthesis mismatch (PPM) remains one out of many factors to be considered during decision-making for the treatment of aortic valve pathologies. The idea of adequate sizing of a prosthetic heart valve was established by Rahimtoola already in 1978. In this article, the author described the phenomenon that the orifice area of a prosthetic heart valve may be too small for the individual patient. PPM is assessed by measurement or projection of the prosthetic effective orifice area indexed to body surface area (iEOA), while it is recommended to use different cut point values for non-obese and obese patients for the categorization of moderate and severe PPM. Several factors influence the accuracy of both the projected and the measured iEOA for PPM assessment, which leads to a certain number of false assignments to the PPM or no PPM group. Despite divergent findings on the impact of PPM on clinical outcomes, there is consensus that PPM should be avoided to prevent sequelae of increased prosthetic gradients after aortic valve replacement. To prevent PPM, it is required to anticipate the iEOA of the prosthesis prior to the procedure. The use of adequate reference tables, derived from echocardiographically measured mean effective orifice area (EOA) values from preferably large numbers of patients, is most appropriate to predict the iEOA. Such tables should be used also for transcatheter heart valves in the future. During the decision-making process, all available options should be taken into account for the individual patient. If the predicted size and type of a surgical prosthesis cannot be implanted, additional surgical procedures, such as annular enlargement with the Manougian technique, or alternative procedures, such as transcatheter aortic valve implantation (TAVI) can prevent PPM. PPM prevention for TAVI patients is a new field of interest and includes anticipation of the iEOA, prosthesis selection, and procedural strategies.

Editorial comment: "Plug-In Hybrid"-Are we ready for this in heart valve surgery?

If we think about plug-in hybrids, the treatment of paravalvular leaks in cardiac surgery may not be the first thing that comes to mind. Yet, there appears to be an attractive analogy between the plug in hybrid car and an interventional device that may be "plugged in" intra-operatively to treat a paravalvular leak. Both technologies provide additional degrees of freedom to the fields, combine different technologies but may also be criticized for their increase in cost, introduction of new problems and their questionable practical need. We address this analogy based on a case series presented in this issue of the Journal of Cardiac Surgery.

Patient-Prosthesis Mismatch Worsens Long-Term Survival: Insights From the FinnValve Registry

BACKGROUND

The impact of patient-prosthesis mismatch (PPM) on long-term outcome after surgical aortic valve replacement (SAVR) is controversial. We sought to investigate the incidence of PPM and its impact on survival and reinterventions in a Finnish nationwide cohort.

METHODS

In the context of the nationwide FinnValve registry, we identified 4097 patients who underwent SAVR with a stented bioprosthesis with or without myocardial revascularization. The indexed effective orifice areas (EOAs) of surgical bioprostheses were calculated using literature-derived EOAs. PPM was graded as moderate (EOA 0.65-0.85 cm²/m²) or severe (EOA ≤0.65 cm²/m²).

RESULTS

The incidence of PPM was 46.0%. PPM was moderate in 38.8% (n = 1579) patients and severe in 7.2% (n = 297) patients. Time-trend analysis showed that the proportion of PPM decreased significantly from 74% in 2009 to 18% in 2017 (P < .01). Severe PPM was associated with increased 5-year all-cause mortality (adjusted hazard ratio [HR], 1.72; 95% confidence interval [CI], 1.07-2.76; P = .02). Severe PPM was not associated with an increased risk of repeat AVR (adjusted HR, 5.90; 95% CI, 0.95-36.5; P = .06). In a subanalysis of patients greater than or equal to 70 years of age, in comparison with no PPM, any PPM (adjusted HR, 1.23; 95% CI, 1.05-1.45; P = .01) and severe PPM (HR, 1.53; 95% CI, 1.17-2.00; P < 0.01) were associated with increased risk of 5-year mortality.

CONCLUSIONS

Severe PPM after SAVR had a negative impact on survival. This study demonstrated that the effects of PPM should not be overlooked in elderly undergoing SAVR.

The effect of patient-prosthesis mismatch on survival after aortic and mitral valve replacement: a 10 year, single institution experience

Background

The evidence on the impact of patient-prosthesis Mismatch (PPM) on survival thus far has been conflicting. The aim of this study was to 1) study the effect of PPM on survival after isolated aortic and mitral valve replacement and 2) Assess the interaction between left ventricular function and PPM on survival.

Methods

The study cohort was patients who underwent isolated Aortic valve replacement (AVR) and Mitral valve replacement (MVR) over a 10-year period from 2008 to 2018. PPM was defined using the projected indexed effective orifice area (EOAi). The cohort was divided into different groups based on the degree of PPM. The severity of PPM was classified using threshold values of EOAi used in the literature. The Kaplan- Meier method was used to compare survival by degree of PPM. Multivariate Cox proportional hazards models were used to generate adjusted hazard ratios (HR) with 95% confidence intervals. An interactive term for ejection fraction (EF) was added to test whether EF modifies the effect of the PPM grade on survival. In addition, sub-group analysis based on left ventricular function was performed.

Results

In the AVR cohort, there were a total of 1953 patients. The distribution of patients in the different PPM categories was as follows: no PPM 59.7%; moderate PPM 36.8%; severe PPM 3.5%. There was no significant difference in survival between the different groups. At 10 years, the adjusted HR between patients with severe PPM versus no PPM was 1.1(CI 0.5–2.4, p >  0.05) and the HR between those with moderate PPM versus no PPM was 0.97 (CI 0.74–1.23, p >  0.05). In the MVR cohort, there were a total of 298 patients. The distribution of PPM is as follows: no PPM 59.4%; and with PPM 40.6%. Again, there was no significant difference in survival between the groups. At 5 years, the adjusted HR between patients with PPM versus no PPM was 1.45 (CI 0.67–3.14, p >  0.05). In both groups, there was no significant interaction between left ventricular function (LVF) and degree of PPM on survival.

Conclusions

In our study cohort, the degree of PPM was not an independent predictor of survival after AVR or MVR. There was also no significant interaction between LV function and degree of PPM on survival.