Comprehensive Hemodynamic Performance and Frequency of Patient-Prosthesis Mismatch of the St. Jude Medical Trifecta Bioprosthetic Aortic Valve Ajay Yadlapati 1, Jimmy Diep 3, Mary-Jo Barnes 2, Tristan Grogan 4, Daniel M. Bethencourt 2, Gabriel Vorobiof 1 1 Department of Medicine, Division of Cardiology, David Geffen School of Medicine at UCLA, Los Angeles, CA, 2 Long Beach Memorial Medical Center, Heart & Vascular Institute, Long Beach, CA, 3 Department of Medicine, Division of Cardiology, University of California Irvine, Irvine, CA, 4 Department of Medicine, Statistics Core, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA Background and aim of the study: The study aim was to evaluate the performance of a new stented pericardial bioprosthesis, the Trifecta (St. Jude Medical, St. Paul, MN, USA), for aortic valve replacement (AVR) with respect to valvular hemodynamics and frequency of patient-prosthesis mismatch (PPM). PPM has been reported in a wide range of bioprosthetic valves following AVR, and has been associated with multiple adverse outcomes. It was hypothesized that the Trifecta aortic valve would have superior hemodynamics and an acceptable incidence of PPM following AVR. Methods: A prospective cohort study was performed between January 2010 and May 2012, following 75 patients (mean age 71.9 ± 11.1 years) who had undergone AVR with a Trifecta valve for aortic stenosis (88%) or regurgitation (12%) at the authors institutions. Intraoperative three-dimensional and Doppler transesophageal echocardiography were used to evaluate hemodynamic variables before and after AVR, as well as pre-discharge. Results: Echocardiographic evaluation showed a preoperative average mean gradient (MG) of 40.6 ± 21.6 mmhg, an average peak gradient (PG) of 72.1 ± 19.4 mmhg, and an average effective orifice area index (EOAI) of 0.39 ± 0.20 cm 2 /m 2. Postoperative mean pressure gradient measurements showed a postoperative average MG of 8.76 ± 3.75 mmhg (p <0.001), an average PG of 19.4 ± 8.6 mmhg (p <0.001), and EOAI of 1.09 ± 0.36 cm 2 /m 2 (p <0.001), which demonstrated a significantly improved hemodynamic performance across all valve sizes. Postoperative MG versus measured EOAI demonstrated a fairly linear relationship (R2 = 0.0703), rather than a rapid increase in MG with EOAI < 0.85 and < 0.65, as was seen with previous valve designs. Severe PPM (defined as EOAI 0.65 cm 2 /m 2 ) was found in four patients (6%), while moderate PPM (EOAI >0.65 and <0.85 cm 2 /m 2 ) was seen in 11 patients (16%). Conclusion: The Trifecta pericardial valve demonstrated excellent hemodynamic performance at all valve sizes, and resulted in very low postoperative transvalvular pressure gradients and PPM, without the need for aortic root enlargement. The Journal of Heart Valve Disease 2014;23:516-523 Each year, aortic valve replacement (AVR) is performed in almost 50,000 patients in the United States (1). Prosthesis-patient mismatch (PPM) occurs when the Presented at the Valves in the Heart of the Big Apple Conference, 12th April 2012, New York, NY, USA, and as a poster at the American College of Cardiology 62nd Annual Scientific Session and ACC-i2 with TCT, 11th March 2013, San Francisco, California, and the American College of Physicians Annual Meeting, 10th April 2013, San Francisco, California, USA Address for correspondence: Gabriel Vorobiof MD, FACC, David Geffen School of Medicine at UCLA, Division of Cardiology & UCLA Cardiovascular Center, 100 UCLA Medical Plaza, Suite 630, Los Angeles, CA 90095, USA e-mail: gvorobiof@mednet.ucla.edu effective orifice area (EOA) of a normally functioning aortic prosthesis is too small in relation to the patient s cardiac output requirements, resulting in high transvalvular pressure gradients. Moderate and severe PPM - defined as an indexed EOA (EOAI) 0.85 cm 2 /m 2 - appears to be variably present following AVR, with reported incidence rates ranging from 30.7% to 53.7% (2-7). PPM presents the left ventricle with a higher resistance to overcome, and can be demonstrated by high transvalvular pressure gradients on echocardiography. This increased afterload seems to underlie the reason behind a slower regression of left ventricular mass and an adverse overall prognosis in patients with PPM (8-10). Copyright by ICR Publishers 2014
Performance of the SJM Trifecta bioprosthetic valve 517 Over the past half-century, the manufacture of artificial heart valves has undergone tremendous changes, with more than 80 models having been introduced since 1950. In 2011, a new-generation pericardial tissue valve, the Trifecta (St. Jude Medical, St. Paul, MN, USA), was introduced and approved by the FDA for the use in AVR (11). The Trifecta valve is a three-leaflet stented pericardial valve designed for supra-annular placement in the aortic position. The stent, excluding the true supra-annular sewing cuff, is covered with porcine pericardial tissue and the valve leaflets are manufactured using bovine pericardial tissue, which is wrapped around the intrinsically distensible titanium stent, rather than mounted inside. Overall, the design is aimed at maximizing valve hemodynamics while minimizing leaflet stresses (12). Previous studies with the Trifecta valve have suggested that hemodynamic performance, EOAs and mean transvalvular pressure gradients may be improved, especially in patients requiring small bioprosthetic valve sizes (13). Thus, it was hypothesized that the short-term hemodynamic performance of the Trifecta stented pericardial tissue bioprosthesis for AVR would have superior hemodynamics and an acceptable incidence of PPM. Clinical material and methods Study design and population A prospective, non-controlled cohort study was performed between January 2010 and May 2012, following 75 patients (24 women, 51 men; mean age 71.9 ± 11.1 years; range: 44 to 87 years), who had undergone AVR for aortic stenosis (88%) or regurgitation (12%) with a Trifecta aortic valve at the authors institutions. The patient baseline demographics are listed in Table I. Table I: Baseline demographics of the patients. Variable Value Age (years) * 71.9 ± 11.1 Body surface area (m 2 ) * 1.92 ± 0.23 Male gender (%) 68.0 Coronary artery disease (%) 36.0 Atrial fibrillation (%) 42.7 Hypertension (%) 92.0 Hyperlipidemia (%) 80.0 COPD (%) 6.7 Asthma (%) 9.3 Cerebrovascular accident (%) 18.7 End-stage renal disease (%) 4.0 Congestive heart failure (%) 30.7 * Values are mean ± SD. COPD: Chronic obstructive pulmonary disease. Intraoperative two- and three-dimensional and Doppler transesophageal echocardiography (TEE) were used to evaluate hemodynamic variables before and after AVR in the operating room, as well as predischarge (mean 5 ± 2 days). Eligibility criteria included all patients who received the Trifecta valve between January 2010 and May 2012. A bioprosthesis was selected if the expected durability of the valve was greater than the patient s expected lifetime. Five cases were excluded from analysis due to postoperative left ventricular outflow tract (LVOT) obstruction (n = 3), the use of Trifecta for an isolated pulmonary valve replacement (n = 1), and an isolated tricuspid valve replacement (n = 1). Aortic root enlargement was not required in any of the patients. Surgical technique An anterior thoracotomy approach was used in all patients who underwent an isolated, primary AVR. The operative technique included a midline sternotomy in 50 patients (66%) and port access via a small anterior thoracotomy in 25 (33%). The prosthesis size was estimated according to the size of the aortic annulus on TEE, but the final size was determined using the manufacturer-supplied replica sizer. Prostheses were implanted using interrupted braided Dacron sutures reinforced with 3 7 mm Teflon felt pledgets placed below the aortic annulus. Aortic root enlargement at the non-coronary sinus was not employed in any of the patients. Patients who required additional procedures such as coronary artery bypass graft(s), redo-avr and AVR with root replacement underwent sternotomy rather than the minimally invasive anterior thoracotomy. These patients were not included in the study cohort. Echocardiographic variables Transthoracic echocardiography (TTE) and TEE were performed using Philips ie33 and Acuson Sequoia instruments. Two-dimensional and, when required, three-dimensional imaging were used to quantify all echocardiographic variables. A complete TTE examination was performed at baseline and before discharge by an experienced echocardiographer. Calculations of hemodynamic parameters were made according to the 2009 American Society of Echocardiography Guidelines Evaluation of Prosthetic Valves (14). All Doppler measurements were averaged over three cardiac cycles in patients with sinus rhythm, and over five cardiac cycles in those with atrial fibrillation. The LVOT diameter was measured immediately proximal to the prosthesis sewing ring to avoid flow acceleration within the lower portion of the prosthesis (14). The EOA was calculated using the
518 Performance of the SJM Trifecta bioprosthetic valve Table II: Hemodynamic performance of the Trifecta aortic valve: Preoperative versus postoperative data. Variable Preoperative Postoperative p-value * Mean gradient (mmhg) 40.6 ± 21.6 8.76 ± 3.75 <0.001 Peak gradient (mmhg) 72.1 ± 3 19.4 ± 8.6 <0.001 EOAI (cm 2 /m 2 ) 0.39 ± 0.20 1.09 ± 0.36 <0.001 Velocity index (LVOT/AV) 0.19 ± 0.07 0.59 ± 0.14 <0.001 by VTI Values are mean ± SD. * Paired t-test. AV: Aortic valve; EOAI: Effective orifice area index; LVOT: Left ventricular outflow tract; VTI: Velocity time integral. continuity equation (LVOT area velocity time integral (VTI) LVOT /VTI valve ), using echo-doppler. The EOAI was calculated using the EOA divided by the patient s body surface area (m 2 ); the BSA was calculated using the Dubois formula (15). The velocity index (VI, a dimensionless ratio) was defined as the ratio of the LVOT VTI divided by the aortic valve continuous-wave spectral Doppler VTI (14). Severe PPM was defined as EOAI <0.65 cm 2 /m 2, moderate PPM as EOAI 0.65-0.85 cm 2 /m 2, and non-significant (i.e., mild or no PPM) as EOAI >0.85 cm 2 /m 2 (16). Statistical analysis Continuous and normally distributed data were reported as mean ± SD. Student s t-test, corrected for Bonferroni adjustment, was used for paired data testing. Transvalvular pressure gradients were performed as a point-to-point statistical analysis. A p-value <0.05 was considered to be statistically significant. All statistical analyses and plots were performed using R, version 2.13.1 (R Foundation for Statistical Computing, Vienna, Austria) and IBM SPSS, version 19 (SPSS, Chicago, IL, USA). Results Echocardiographic evaluation showed a preoperative average mean gradient (MG) of 40.6 ± 21.6 mmhg, an average peak gradient (PG) of 72.1 ± 19.4 mmhg, an average EOA of 0.7 ± 0.3 cm 2, and an average EOAI of 0.4 ± 0.2 cm 2 /m 2. Postoperative measurements (Table II) showed a postoperative average MG of 8.76 ± 3.75 mmhg, an average PG of 19.4 ± 8.6 mmhg, and an EOAI of 1.09 ± 0.36 cm 2 /m 2, which demonstrated a significantly improved hemodynamic performance across all valve sizes (Table III; Fig. 1). The 21 mm (n = 28; 40%), 23 mm (n = 19; 27%) and 25 mm (n = 14; 20%) valves were most frequently utilized, and showed statistically significant improvements in Figure 1: St. Jude Medical Trifecta aortic valve. Preoperative and postoperative mean gradient and effective orifice area index (EOAI), by valve size. Figure 2: St. Jude Medical Trifecta aortic valve. Preoperative and postoperative mean gradient by valve size.
Performance of the SJM Trifecta bioprosthetic valve 519 Figure 3: St. Jude Medical Trifecta aortic valve. Preoperative and postoperative peak gradient by valve size. MG (Fig. 2), PG (Fig. 3), EOAI (Fig. 4), and also VI by VTI (Fig. 5). The 19 mm (n = 2; 3%), 27 mm (n = 6; 9%) and 29 mm (n = 1; 1%) valves comprised only nine cases (13%) within the study cohort. These prostheses showed similar improvements in hemodynamics, but the statistical significance was neutral given the small sample size for this subgroup. The postoperative MG versus measured EOAI (Fig. 6) showed a fairly linear relationship (R2 = 0.0703), rather than a rapid increase in MG with EOAI <0.85 and <0.65 cm 2 /m 2, as seen with previous valve designs (17). The MG remained low (<10 mmhg), regardless of valve size or measured EOAI. Severe PPM was found in four patients (6%), and moderate PPM in 11 patients (16%). The average postoperative MG in patients with moderate-to-severe PPM was 9.9 mmhg, and 9.1 mmhg in patients with EOAI >0.85 cm 2 /m 2. No aortic root enlargements were required. The expected versus achieved EOAIs are shown graphically in Figures 7 and 8. In the past, the valve manufacturers have attempted to simplify the implantation process by providing charts which include the expected EOAI for their prosthesis. A caveat with these charts is that the expected EOA data must truly be reliable; otherwise the chart can misguide the implanting surgeon (18). To help improve the predictive abilities of the expected EOAI, manufacturers also provide a replica sizer to help the surgeon better estimate which valve size to use. Achieved EOAIs were calculated measurements based on echocardiographic data. Figure 4: St. Jude Medical Trifecta aortic valve. Preoperative and postoperative EOAI by valve size. Figure 5: St. Jude Medical Trifecta aortic valve. Preoperative and postoperative velocity index by valve size.
520 Performance of the SJM Trifecta bioprosthetic valve Table III: Hemodynamic performance of the Trifecta aortic valve: Preoperative versus postoperative data, by valve size. Variable/ Preoperative * Postoperative * p-value # Valve size (mm) Mean gradient 19 41.0 ± 7.1 (n = 2) 11.3 ± 6.0 (n = 2) 0.192 21 46.2 ± 24.9 (n = 28) 10.6 ± 4.2 (n = 28) <0.001 23 39.4 ± 22.3 (n = 19) 8.2 ± 3.0 (n = 19) <0.001 25 40.4 ± 18.7 (n = 14) 8.4 ± 3.3 (n = 14) <0.001 27 33.3 ± 20.9 (n = 6) 6.2 ± 3.4 (n = 6) 0.002 29 15.0 (n = 1) 5.0 (n = 1) - Peak gradient 19 67.0 ± 5.7 (n = 2) 22.5 ± 9.2 (n = 2) 0.148 21 80.8 ± 21.5 (n = 28) 36.9 ± 8.3 (n = 28) <0.001 23 68.9 ± 35.1 (n = 19) 21.0 ± 9.7 (n = 19) <0.001 25 76.4 ± 34.6 (n = 14) 17.6 ± 6.4 (n = 14) <0.001 27 57.2 ± 32.4 (n = 6) 12.1 ± 6.7 (n = 6) 0.016 29 35 (n = 1) 10 (n = 1) - EOAI 19 0.37 ± 0.07 (n = 2) 0.68 ± 0.03 (n = 2) 0.141 21 0.39 ± 0.21 (n = 28) 1.03 ± 0.18 (n = 28) <0.001 23 0.29 ± 0.15 (n = 19) 0.92 ± 0.21 (n = 19) <0.001 25 0.47 ± 0.15 (n = 14) 1.33 ± 0.44 (n = 14) <0.001 27 0.26 ± 0.10 (n = 6) 1.33 ± 0.55 (n = 6) 0.026 29 1.09 (n = 1) 1.40 (n = 1) - Velocity index (LVOT/AV) by VTI 19 0.23 ± 0.01 (n = 2) 0.43 ± 0.07 (n = 2) 0.186 21 0.22 ± 0.11 (n = 28) 0.60 ± 0.09 (n = 28) <0.001 23 0.20 ± 0.09 (n = 19) 0.57 ± 0.14 (n = 19) <0.001 25 0.22 ± 0.05 (n = 14) 0.60 ± 0.16 (n = 14) <0.001 27 0.15 ± 0.07 (n = 6) 0.70 ± 0.16 (n = 6) 0.005 29 0.30 (n = 1) 0.39 (n = 1) - * Values are mean ± SD. # Paired t-test. AV: Aortic valve; EOAI: Effective orifice area index; LVOT: Left ventricular outflow tract; VTI: Velocity time integral. Figure 6: St. Jude Medical Trifecta aortic valve. Mean gradient versus effective orifice area index (EOAI). Figure 7: St. Jude Medical Trifecta aortic valve. Achieved effective orifice area index (EOAI) versus expected EOAI.
Performance of the SJM Trifecta bioprosthetic valve 521 Figure 8: St. Jude Medical Trifecta aortic valve. Frequency of achieved effective orifice area index (EOAI) versus expected EOAI. Discussion Over the past decade, several models of tissue heart valves have been introduced, the main rationale for using bioprosthetic valves being their low thrombogenicity such that anticoagulation will not be required per se. Consequently, these valves seem to be eminently suitable for patients with isolated aortic valve disease, who are in sinus rhythm and do not have any concomitant cardiomyopathy that would necessitate anticoagulation (5). Many improvements in bioprosthetic valve designs have been introduced over time. Optimizing hemodynamics to prevent PPM and improve durability revived the use of stentless bioprostheses during the early 1990s (6). Although stentless AVR required longer cross-clamp and cardiopulmonary bypass times, the postoperative outcomes were indeed favorable. In patients with a depressed left ventricular function, the operative outcomes were better in stentless valves owing to the larger orifice area when the full-root technique was applied to avoid PPM (19). Additionally, several studies demonstrated superior hemodynamics with almost no increase in MG under exercise with stentless valves compared to mechanical valves after AVR (20, 21). Although stentless bioprostheses were originally thought to replace stented biological valves due to a better hemodynamic performance and longer durability, many surgeons still use stented valves because they are easier to implant, especially when using a minimally invasive approach. Concerns regarding PPM can be addressed by augmenting the aortic root (22) or by replacing the aortic root along with the valve (23). Gulbins et al. (24) reported that less than 12% of all aortic valve prostheses implanted in Europe were stentless. This low proportion of stentless valves was attributed to similar hemodynamic performance and an easier implanting technique of new-generation bioprostheses such as the Carpentier- Edwards Perimount Magna valve. Stentless valves with an easier implantation technique may increase the market of stentless bioprostheses in the future (25). All prosthetic valves have an EOA which is smaller than that of the native human valve, and therefore will have some degree of PPM. Significant PPM is defined as an EOA that is too small in relation to the patient s body size (7), and results in high postoperative gradients. Pibarot and colleagues (16) described the use of EOAI to predict significant PPM for the aortic valve, using published EOA data supplied to the FDA by the valve manufacturers but divided by the patient s BSA; thus, they defined PPM as an EOAI 0.85 cm 2 /m 2 (15,26-28). This threshold was chosen because, at smaller EOAI-values, the transvalvular gradient showed a rapid increase. According to this definition, PPM can be divided into moderate PPM, with EOAI 0.65-0.85 cm 2 /m 2 and severe PPM, with EOAI <0.65 cm 2 /m 2. In the present study, EOAI was measured directly in the operating room after implantation. Using the same threshold values, severe PPM was found in four patients (6%), and moderate PPM in 11 (16%). These data were consistent with the large multicenter data reported by Bavaria et al. (12), where the frequency for mild to moderate PPM was 23% and for severe PPM was 2%. The present data were also consistent with those of other investigators, who showed no evidence of severe PPM with the Trifecta valve in 200 patients (29). In addition to PPM, the Trifecta valve has also performed favorably with regards to hemodynamic performance during exercise, when compared to the Medtronic Freestyle aortic valve bioprosthesis (30). When compared to other supra-annular valves, the Trifecta valve revealed significantly higher aortic valve areas at the six-month follow up, although after multivariate covariance adjustment the type of prosthesis could not be identified as an independent factor influencing the mean pressure gradients or aortic valve area at the six-month follow up. Hence, further long-term data are required to fully evaluate the long-term performance of the Trifecta valve (31). Among patients undergoing AVR, PPM is a commonly encountered problem that leads to a worsened hemodynamic function, less regression of left ventricular hypertrophy (LVH), and more cardiac events with lower survival rates (12,16). It has also been shown that an incomplete regression of left ventricular mass and function after AVR is related to poor long-term survival (3). Conversely, an improved hemodynamic performance resulted in a faster left
522 Performance of the SJM Trifecta bioprosthetic valve ventricular mass reduction in patients with aortic stenosis and LVH (2). Hence, the minimization of postoperative PGs across the implanted valve is one of the most important goals of AVR. Postoperative PPM can be avoided through optimal prosthesis selection in the individual patient by calculating the EOAI prior to surgery. This is particularly important in patients with left ventricular dysfunction and/or severe LVH (7). This experience with the Trifecta valve, in a preliminary single-center study, demonstrated excellent immediate-term clinical and hemodynamic outcomes, though long-term outcomes will need to be assessed to help understand the hemodynamic performance over time. Whilst the excellent hemodynamic performance of the Trifecta valve resulted in impressively low rates of severe PPM, the plan is to continue the follow up at six and 12 months to evaluate the incidence of PPM and its effect on longterm outcome, as previously recommended (17). Study limitations The primary limitation was that the study involved only a moderate cohort size (n = 75) from a single institution. In addition, the EOAI data were obtained immediately after surgery and may have been influenced by factors such as changes in preload, afterload, and inotropy. All measurements, however, were repeated on TTE prior to discharge and showed no significant changes. Another limitation was that no comparison group was used; rather, historical rates of PPM were used. Finally, the relevance of these hemodynamic changes was not correlated with clinical events, although previous studies have shown severe PPM to be a poor prognostic marker and a valid surrogate for future adverse events. In conclusion, the Trifecta aortic valve bioprosthesis demonstrated excellent hemodynamic performance across all valve sizes, with low mean gradients and high velocity ratios indicating a low resistance to aortic valve outflow. This hemodynamic performance was maintained in patients with low EOAI (see Fig. 6). The transvalvular gradients remained low independent of the valve size, the measured EOAI, or the predicted EOAI. The Trifecta valve can be implanted with open or minimally invasive surgical approaches, as well as potentially minimizing the need for aortic root enlargement. However, confirmation of these preliminary results is required by performing longterm outcome studies. Acknowledgements Dr. Vorobiof is a consultant at St. Jude Medical and is on the Speakers Bureau for Lantheus Medical Imaging. Dr. Bethencourt is a consultant for Intuitive Surgical, St. Jude Medical, Edwards Lifesciences, and Medtronic. References 1. Freeman RV, Otto CM. Spectrum of calcific aortic valve disease: Pathogenesis, disease progression, and treatment strategies. Circulation 2005;111: 3316-3326 2. Head SJ, Mokhles MM, Osnabrugge RL, et al. The impact of prosthesis-patient mismatch on longterm survival after aortic valve replacement: A systematic review and meta-analysis of 34 observational studies comprising 27 186 patients with 133 141 patient-years. Eur Heart J 2012;33:1518-1529 3. Hernandez-Vaquero D, Llosa JC, Diaz R, et al. Impact of patient-prosthesis mismatch on 30-day outcomes in young and middle-aged patients undergoing aortic valve replacement. J Cardiothorac Surg 2012;7:46 4. Van Linden A, Kempfert J, Blumenstein J, et al. Prosthesis-patient mismatch after transcatheter aortic valve implantation using the Edwards SAPIEN prosthesis. Thorac Cardiovasc Surg 2012;61:414-420 5. Jamieson WR, Ye J, Higgins J, et al. Effect of prosthesis-patient mismatch on long-term survival with aortic valve replacement: Assessment to 15 years. Ann Thorac Surg 2010;89:51-58; discussion 59 6. Yottasurodom C, Namthaisong K, Porapakkham P, et al. Patient-prosthesis mismatch has no influence on in-hospital mortality after aortic valve replacement. J Med Assoc Thailand 2012;95 (Suppl.8):S64-S70 7. Rahimtoola SH. The problem of valve prosthesispatient mismatch. Circulation 1978;58:20-24 8. Tasca G, Brunelli F, Cirillo M, et al. Impact of valve prosthesis-patient mismatch on left ventricular mass regression following aortic valve replacement. Ann Thorac Surg 2005;79:505-510 9. Ruel M, Rubens FD, Masters RG, et al. Late incidence and predictors of persistent or recurrent heart failure in patients with aortic prosthetic valves. J Thorac Cardiovasc Surg 2004;127:149-159 10. Ruel M, Al-Faleh H, Kulik A, Chan KL, Mesana TG, Burwash IG. Prosthesis-patient mismatch after aortic valve replacement predominantly affects patients with preexisting left ventricular dysfunction: Effect on survival, freedom from heart failure, and left ventricular mass regression. J Thorac Cardiovasc Surg 2006;131:1036-1044 11. St. Jude Medical. Trifecta Valve P-MAASoSaED, P100029, 2011 12. Bavaria JE, Desai ND, Cheung A, et al. The St. Jude Medical Trifecta aortic pericardial valve: Results
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