We reported seven cases of early SVD among 110 Trifecta valve implantations performed between 2012 and 2017 at our single center. In our study, the free rate of structural valve degeneration was 92.6% at seven years, similar to outcomes of other reports .
Previous studies have shown that a high postoperative mean pressure gradient and PPM are related to structural valve degeneration [16–18]. In our study, the mean pressure gradient and peak velocity in the first echocardiography were higher in patients with SVD. The most common cause of SVD was a noncoronary cusp tear. Previous studies have reported similar pathological findings. We estimate that the high mean pressure gradient increases the hemodynamic stress on the externally mounted leaflet, and the stress may be particularly high on the NCC commissures. This stress could lead to leaflet tears. Patients with a high mean pressure gradient and peak velocity should be closely monitored.
Subvalvular Pannus formations were observed in two patients. The pannus forms due to surgical injury leading to thrombus formation, release of cytokines, and deposition of inflammatory cells . Two patients with pannus formations in our study underwent reoperation for aortic regurgitation. Excessive pannus formation may confer hemodynamic stress to the leaflet.
In one patient, the RCC-LCC and LCC-NCC commissures adhered to the sinus of Valsalva.
Attachment to the Valsalva sinus restricts leaflet movement and incomplete leaflet coaptation. It is probable that the externally mounted leaflet design of the Trifecta valve leads to the attachment of the Valsalva sinus, resulting in limited leaflet motion and valve insufficiency. A previous report showed the same pathological findings . They reported that a small aortic root was predisposing factor. In our study, the Valsalva size tended to be smaller in patients with SVD, although the difference was not significant. Cleveland et al. reported that oversizing of bioprosthetic valves resulted in an increased pressure gradient, and the Trifecta valve was more sensitive to oversizing than other bioprosthetic valves due to the externally mounted leaflet design . Implanting the oversized Trifecta valve in the small annulus may interfere with the expansion of the bioprosthesis, narrowing the EOAI, and creating accelerated blood flow. In addition, implanting the Trifecta in a small sinus of Valsalva may stress the outer-mounted valve. We used Trifecta valves in older adults, especially in patients with small annuli. Thus, we used 19 mm valves with a higher frequency (43%) than those used in previous studies [13, 21]. Although there were no statistically significant differences in our small sample, the SVD-free rate of the 19 mm valves tended to be higher. This result raises the possibility that the small size of Trifecta for a small annulus or Valsalva sinus may be a risk factor for early SVD. We used Trifecta vavles for patients with a small annulus because the Trifecta has good hemodynamic performance. However, this strategy conversely caused SVD. It may be better to consider the enlargement of the annulus rather than using an externally mounted leaflet valve.
This study had several limitations. Our analysis was retrospective and limited to a small number of patients. Although multivariate analysis is necessary to analyze the risk factors, statistically valid multivariate analysis was difficult due to the small sample size. More well-designed and large studies are essential to understand the mechanism of early Trifecta valve failure. Follow-up echocardiographic studies were performed in a variety of clinical settings.