Background
Patient-prosthesis mismatch (PPM) has been reported with a wide range of bioprosthetic valves after aortic valve replacement (AVR) and has been associated with multiple adverse outcomes. The aim of this study was to test the hypothesis that a novel low-profile stented pericardial tissue bioprosthesis for AVR, the Trifecta aortic valve, would have superior hemodynamics, a lower incidence of PPM, and an improvement in clinical outcomes. Its hemodynamic performance was evaluated, and a comparison was performed with a traditional stented pericardial bioprosthesis (Epic) with respect to hemodynamics, PPM, and clinical events.
Methods
One hundred twenty-four patients (mean age, 73.6 ± 11.0 years) underwent AVR. Prosthetic valve types used were Trifecta ( n = 75 [60.5%]) and Epic ( n = 49 [39.5%]). Intraoperative transesophageal echocardiography was used to evaluate hemodynamic variables before and after AVR.
Results
Postoperative comparison of the Epic valve and the Trifecta valve revealed a lower mean pressure gradient (16.5 ± 6.7 vs 8.8 ± 3.4 mm Hg, P < .001), a lower peak gradient (33.3 ± 11.8 vs 19.4 ± 8.6 mm Hg, P < .001), and higher indexed effective orifice area (0.8 ± 0.2 vs 1.1 ± 0.4 cm 2 /m 2 , P < .001), favoring the Trifecta valve across several valve sizes. Severe PPM (6% vs 27%, P < .001) and valvular-related complications at follow-up (14.3% vs 36.7%, P = .005) were less frequent in the Trifecta group.
Conclusions
The hemodynamic performance of the Trifecta valve is superior to that of the Epic valve across many conventional prosthesis sizes, and its implantation resulted in lower rates of severe PPM. These improvements were associated with lower valvular-related adverse events.
Nearly 50,000 aortic valve replacement (AVR) procedures are performed each year in the United States. Patient-prosthesis mismatch (PPM) occurs when the effective orifice area (EOA) of a normally functioning aortic prosthesis is too small in relation to a patient’s cardiac output requirements, resulting in high transvalvular pressure gradients. Moderate (defined as indexed EOA [EOAi] ≤ 0.85 cm 2 /m 2 ) and severe PPM (defined as EOAi < 0.65 cm 2 /m 2 ) appears to be variably present after AVR, with reported incidence rates of 30.7% to 53.7%. PPM presents the left ventricle a higher resistance to overcome and seems to underlie the reason behind a slower regression of left ventricular (LV) mass and an overall adverse prognosis in patients with PPM.
The manufacturing process of cardiac valves has gone through tremendous changes over the past half century. More than 80 models of artificial valves have been introduced since 1950. In 2011, a new-generation pericardial tissue valve, the Trifecta valve (St. Jude Medical, St. Paul, MN), was introduced and approved by the US Food and Drug Administration for use in AVR. The Trifecta valve is a novel low-profile 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 a distensible titanium stent, rather than mounted inside. Overall, the design is aimed at maximizing valve hemodynamics while minimizing leaflet stresses. Preliminary work suggests that hemodynamic performance, EOAs, and mean transvalvular pressure gradients may be improved, especially in patients requiring small bioprosthetic valves.
We sought to comprehensively evaluate the hemodynamic performance, incidence of PPM, and early clinical outcomes of the Trifecta bioprosthesis for AVR in a real-world setting and to perform a comparison with a widely used conventional stented bioprosthetic porcine valve (Epic; St. Jude Medical).
Methods
Study Design
The study was approved by the MemorialCare and University of California, Los Angeles, institutional review boards. A prospective cohort study was performed from January 2010 to May 2012. One hundred twenty-four consecutive patients were screened, and 111 were enrolled (33% women; mean age, 73.6 ± 11.0 years; range, 44–87 years). All patients underwent AVR for aortic stenosis (93.5%) or aortic regurgitation (6.5%) with either the Trifecta ( n = 75) or Epic ( n = 49) aortic valve. Exclusion criteria were use of the valve in a nonaortic position and postoperative LV outflow tract (LVOT) obstruction. Thirteen patients were excluded from analysis (five Trifecta, eight Epic) because of postoperative LVOT obstruction ( n = 5), incomplete echocardiographic data ( n = 6), and use of the Trifecta valve for isolated pulmonary and tricuspid valve replacement ( n = 2). The Epic valves were implanted in a consecutive manner from January 2010 to August 2011. The Trifecta valves were implanted in a consecutive manner from May 2011 to May 2012. The choice of aortic prosthesis was left to the individual surgeon and depended on clinical, echocardiographic, patient, and referring physician factors. Baseline demographics did not differ significantly between these two groups except for age, for which there appeared to be a slightly younger cohort favoring the Trifecta group ( P < .03; Table 1 ). Prosthetic valve types used were Trifecta ( n = 75 [60.5%]) and Epic ( n = 49 [39.5%]). Overall for both groups combined, implanted prosthetic valve sizes were 19 mm in seven patients (5.6%), 21 mm in 39 (31.4%), 23 mm in 45 (36.3%), 25 mm in 25 (20.2%), 27 mm in seven (5.6%), and 29 mm in one (1.0%). Intraoperative three-dimensional and Doppler transesophageal echocardiography was used to evaluate hemodynamic variables before and after AVR in the operating room, as well as before discharge (at a mean of 5 ± 2 days). Operative details are shown in Table 2 .
| Variable | Epic ( n = 49) | Trifecta ( n = 75) | P |
|---|---|---|---|
| Age (y) | 76.3 (10.5) | 71.9 (11.1) | .030 |
| Body surface area (m 2 ) | 1.89 (0.23) | 1.92 (0.23) | .412 |
| Men | 31 (63.3%) | 51 (68.0%) | .586 |
| Coronary artery disease | 21 (42.9%) | 27 (36.0%) | .443 |
| Atrial fibrillation | 25 (51.0%) | 32 (42.7%) | .361 |
| Hypertension | 44 (89.8%) | 69 (92.0%) | .673 |
| Hyperlipidemia | 36 (73.5%) | 60 (80.0%) | .395 |
| Chronic obstructive pulmonary disease | 6 (12.2%) | 5 (6.7%) | .340 |
| Asthma | 4 (8.2%) | 7 (9.3%) | .823 |
| Cerebrovascular accident | 6 (12.2%) | 14 (18.7%) | .342 |
| End-stage kidney disease | 0 (0.0%) | 3 (4.0%) | .218 |
| Cardiac heart failure | 11 (22.4%) | 23 (30.7%) | .316 |
| Variable | Epic ( n = 41) | Trifecta ( n = 70) | P |
|---|---|---|---|
| Concomitant CABG | 10 (24.4%) | 12 (17.1%) | .355 |
| Concomitant mitral valve replacement | 8 (19.5%) | 7 (10.0%) | .157 |
| Aortic root enlargement | 0 (0.0%) | 0 (0.0%) | — |
| Preoperative severe annular calcification | 3 (7.3%) | 5 (7.1%) | >.99 |
| Preoperative moderate annular calcification | 12 (29.3%) | 21 (30.0%) | .935 |
| Preoperative severe aortic regurgitation | 3 (7.3%) | 6 (8.6%) | >.99 |
| Preoperative moderate aortic regurgitation | 5 (12.2%) | 8 (11.4%) | >.99 |
| Preoperative mild aortic regurgitation | 15 (36.6%) | 22 (31.4%) | .578 |
Surgical Technique
Operative technique included midline sternotomy in 80 patients (65%) and port access via small anterior thoracotomy in 44 patients (35%). Prosthesis size was estimated according to the size of the aortic annulus on transesophageal echocardiography. Despite known differences in valve replica sizers across various prosthesis models and manufacturers, the final annular size was determined by the surgeon guided by the manufacturer-supplied replica sizer. No adjustment was made for LVOT measurements. 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 noncoronary sinus was not used in any of the patients.
Echocardiographic Variables
Intraoperative transesophageal echocardiography was performed using a Philips iE33 (Philips Medical Systems, Andover, MA) with X7-2t transducers. Two-dimensional, M-mode, and Doppler parameters were used to quantify echocardiographic variables. A complete transesophageal echocardiographic examination was performed at baseline in the operating room before surgery and was repeated at the completion of surgery. Transthoracic echocardiography was also performed before discharge by an experienced echocardiographer. Hemodynamic parameters were calculated according to the 2009 American Society of Echocardiography guidelines for the evaluation of prosthetic valves. All Doppler measurements were obtained with standard Doppler beam alignment and averaged over three cardiac cycles in patients in sinus rhythm and over five cardiac cycles in those with atrial fibrillation. LVOT diameter was measured immediately proximal to the prosthesis sewing ring and spectral Doppler was obtained at this level to avoid flow acceleration within the lower portion of the prosthesis. EOA was calculated using the continuity equation (LVOT area × LVOT velocity-time integral [VTI]/aortic valve VTI) using Doppler echocardiography. EOAi was calculated by dividing EOA by the patient’s body surface area (in square meters). Body surface area was calculated using the formula of Du Bois and Du Bois. Velocity index (dimensionless ratio) was defined as the ratio of the pulsed-wave Doppler LVOT VTI to the aortic valve continuous-wave spectral Doppler aortic valve VTI. The categorization of PPM was based on EOAi, with severe PPM defined as EOAi < 0.65 cm 2 /m 2 , moderate PPM as EOAi > 0.65 and ≤ 0.85 cm 2 /m 2 , and mild or no PPM as EOAi > 0.85 cm 2 /m 2 .
Statistical Analysis
Continuous and normally distributed variables were reported as mean ± SD. Student’s t tests were used to compare continuous variables between the two valve groups. To control the family-wise type 1 error rate, we calculated Bonferroni-adjusted P values. For categorical variables, differences between the two valve groups were examined using χ 2 or Fisher’s exact tests as appropriate. Linear regression was used to assess the relationship between the mean gradient (MG) and the EOAi measurements. P values < .05 were considered to indicate statistical significance. 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, Inc, Chicago, IL).
End Point Definitions
Adverse events were classified according to the standardized definitions from the Society of Thoracic Surgeons and American Association for Thoracic Surgery guidelines for reporting morbidity and mortality and cardiac valvular operations and the requirements of the Food and Drug Administration. A bleeding event was defined as any episode of major internal or external bleeding that causes death, hospitalization, or permanent injury (e.g., vision loss) or necessitates transfusion. A stroke was defined as a prolonged (>72 hours) or permanent neurologic deficit that is usually associated with abnormal results on magnetic resonance imaging or computed tomographic scans. Acute kidney injury was defined as an increase in creatinine of >50% from baseline.
Patient Follow-Up
Patients were followed for a minimum of 1 year and observed for valvular complications, including myocardial infarction, vascular complications, bleeding, acute kidney injury, cerebrovascular accidents, and vascular-related hospitalizations. Adverse clinical events were retrospectively extracted from patients’ electronic health records. The mean duration of follow-up was 21.2 ± 7.9 months. One-year follow-up was completed in 98.4% of patients.
Results
Preoperative echocardiographic evaluation of the Epic and Trifecta valves showed no significant differences in MG (37.5 ± 14.4 vs 40.6 ± 21.6 mm Hg, P = .267), peak gradient (PG) (68.4 ± 22.5 vs 72.1 ± 19.4 mm Hg, P = .356), and EOAi (0.34 ± 0.1 vs 0.39 ± 0.2 cm 2 /m 2 , P = .679) ( Table 3 ). Postoperative comparison of hemodynamics revealed significant improvements in MG (16.5 ± 6.7 vs 8.8 ± 3.8 mm Hg, P < .001), PG (33.3 ± 11.8 vs 19.4 ± 8.6 mm Hg, P < .001), and EOAi (0.8 ± 0.2 vs 1.1 ± 0.4 cm 2 /m 2 , P < .001) favoring the Trifecta valve ( Table 4 ). Table 5 and Figure 1 demonstrate improvements in transvalvular hemodynamics for the Trifecta aortic valve. Specifically, there were significantly lower MGs with the 21-mm to 27-mm Trifecta valves, lower PGs with the 21-mm to 25-mm valves, higher values of EOAi with the 21-mm and 27-mm valves, and higher velocity indices with the 21-mm valve. Postoperative MG and EOAi demonstrated a shift upward in the hemodynamic curve for the Epic valve compared with the Trifecta valve for any given valve’s EOAi.
| Variable | Epic ( n = 41) | Trifecta ( n = 70) | P |
|---|---|---|---|
| PG (mm Hg) | 68.4 ± 22.5 | 72.1 ± 19.4 | .356 |
| MG (mm Hg) | 37.5 ± 14.4 | 40.6 ± 21.6 | .267 |
| EOA (cm 2 ) | 0.65 ± 0.3 | 0.72 ± 0.4 | .273 |
| EOAi (cm 2 /m 2 ) | 0.34 ± 0.1 | 0.39 ± 0.2 | .679 |
| LVOT diameter (cm) | 1.92 ± 0.5 | 2.11 ± 0.3 | .013 |
| Stroke volume (mL) | 59 ± 22 | 65 ± 21 | .135 |
| Ejection fraction (%) | 61 ± 12 | 60 ± 14 | .793 |
| LVEDD (cm) | 4.94 ± 0.8 | 4.94 ± 1.0 | >.99 |
| Variable | Epic ( n = 41) | Trifecta ( n = 70) | P |
|---|---|---|---|
| MG (mm Hg) | 16.5 ± 6.7 | 8.8 ± 3.8 | <.001 |
| PG (mm Hg) | 33.3 ± 11.8 | 19.4 ± 8.6 | <.001 |
| EOA (cm 2 ) | 1.4 ± 0.5 | 2.1 ± 0.8 | <.001 |
| EOAi (cm 2 /m 2 ) | 0.8 ± 0.2 | 1.1 ± 0.4 | <.001 |
| Velocity index (LVOT/AV) by VTI | 0.4 ± 0.1 | 0.59 ± 0.1 | <.001 |
| Stroke volume | 64.57 ± 29.8 | 63.24 ± 21.8 | .788 |
| Variable | Epic | Trifecta | P |
|---|---|---|---|
| MG (mm Hg) | |||
| 19 mm | 15.2 ± 9.1 ( n = 5) | 11.3 ± 6.0 ( n = 2) | .634 |
| 21 mm | 19.2 ± 7.9 ( n = 11) | 10.6 ± 4.2 ( n = 28) | <.001 |
| 23 mm | 15.4 ± 6.1 ( n = 15) | 8.2 ± 3.0 ( n = 19) | .002 |
| 25 mm | 14.1 ± 4.0 ( n = 10) | 8.4 ± 3.3 ( n = 14) | .002 |
| 27 mm | 15.6 ( n = 1) | 6.2 ± 3.4 ( n = 6) | .053 |
| 29 mm | ( n = 0) | 5.0 ( n = 1) | — |
| PG (mm Hg) | |||
| 19 mm | 34.7 ± 18.2 ( n = 5) | 22.5 ± 9.2 ( n = 2) | .461 |
| 21 mm | 36.4 ± 14.0 ( n = 11) | 19.9 ± 9.0 ( n = 28) | <.001 |
| 23 mm | 29.9 ± 10.2 ( n = 15) | 21.0 ± 9.7 ( n = 19) | .033 |
| 25 mm | 34.2 ± 7.0 ( n = 10) | 17.6 ± 6.4 ( n = 14) | <.001 |
| 27 mm | 24.8 ( n = 1) | 12.1 ± 6.7 ( n = 6) | .139 |
| 29 mm | ( n = 0) | 10 ( n = 1) | — |
| EOA (cm 2 ) | |||
| 19 mm | 1.08 ± 0.69 ( n = 5) | 1.08 ± 0.00 ( n = 2) | .991 |
| 21 mm | 1.22 ± 0.46 ( n = 11) | 1.75 ± 0.40 ( n = 28) | .004 |
| 23 mm | 1.52 ± 0.42 ( n = 15) | 1.87 ± 0.40 ( n = 19) | .052 |
| 25 mm | 1.73 ± 0.19 ( n = 10) | 2.70 ± 0.84 ( n = 14) | .041 |
| 27 mm | 1.89 ( n = 1) | 2.93 ± 1.18 ( n = 6) | .308 |
| 29 mm | ( n = 0) | 2.38 ( n = 1) | — |
| EOAi (cm 2 /m 2 ) | |||
| 19 mm | 0.69 ± 0.34 ( n = 5) | 0.68 ± 0.03 ( n = 2) | .971 |
| 21 mm | 0.73 ± 0.28 ( n = 11) | 1.03 ± 0.18 ( n = 28) | .009 |
| 23 mm | 0.77 ± 0.21 ( n = 15) | 0.92 ± 0.21 ( n = 19) | .067 |
| 25 mm | 0.80 ± 0.14 ( n = 10) | 1.33 ± 0.44 ( n = 14) | .036 |
| 27 mm | 0.83 ( n = 1) | 1.33 ± 0.55 ( n = 6) | .477 |
| 29 mm | ( n = 0) | 1.40 ( n = 1) | — |
| Velocity index (LVOT/AV) by VTI | |||
| 19 mm | 0.35 ± 0.22 ( n = 5) | 0.43 ± 0.07 ( n = 2) | .654 |
| 21 mm | 0.42 ± 0.15 ( n = 11) | 0.60 ± 0.09 ( n = 28) | .003 |
| 23 mm | 0.47 ± 0.14 ( n = 15) | 0.57 ± 0.14 ( n = 19) | .164 |
| 25 mm | 0.49 ± 0.07 ( n = 10) | 0.60 ± 0.16 ( n = 14) | .194 |
| 27 mm | 0.39 ( n = 1) | 0.70 ± 0.16 ( n = 6) | .172 |
| 29 mm | ( n = 0) | 0.39 ( n = 1) | — |
| LVOT (cm) | |||
| 19 mm | 1.74 ± 0.20 ( n = 5) | 1.80 ± 0.14 ( n = 2) | .721 |
| 21 mm | 1.96 ± 0.27 ( n = 11) | 1.94 ± 0.17 ( n = 28) | .890 |
| 23 mm | 2.00 ± 0.22 ( n = 15) | 2.12 ± 0.23 ( n = 19) | .134 |
| 25 mm | 2.19 ± 0.18 ( n = 10) | 2.30 ± 0.20 ( n = 14) | .351 |
| 27 mm | 2.20 ( n = 1) | 2.30 ± 0.28 ( n = 6) | .677 |
| 29 mm | ( n = 0) | 2.80 ( n = 1) | — |
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