Recently, a new bovine pericardial stented bioprosthesis for the aortic position, the Labcor Dokimos plus (LDP), became available in Europe. The design features are a low profile stent with externally mounted leaflets [1]. Yet, no contemporary data about clinical outcome and hemodynamic performance are available. We report about our perioperative experience with this substitute, the early clinical outcome and hemodynamic performance.

Postoperative complications included re-exploration for bleeding, which had to be performed in four patients. Furthermore, eight patients developed acute renal insufficiency and required temporary dialysis. Insertion of a permanent pacemaker became necessary in six patients. There were no strokes or deep sternal wound infections. One case of early postoperative endocarditis occurred, which led to a successful secondary valve replacement at the 30th postoperative day. Patients were discharged after a mean of 10.5 ± 6.9 days.

Conventional aortic valve replacement is still a gold standard for patients with relevant aortic valve disease without excessive risk profile. Biological substitutes are recommended for patients older than 65 years or those with contraindications to systemic anticoagulation [2, 3]. Stented biological substitutes are easy to implant and show acceptable hemodynamic performances. However, there is still the necessity to improve these valves concerning hemodynamic properties and clinical performance as well as durability. The LDP was launched in Europe in 2013. It´s innovative design combined with a novel anti-calcification treatment makes it a promising substitute in the category of stented bioprostheses. To our knowledge, this is the first study that reports early postoperative outcome and hemodynamic data in a European population.

Procedural data, including cross clamp times, were comparable to other stented bio-prosthetic heart valves and verify the simplicity and safety of the LDP-implantation [4–6]. However, one has to consider the low mean age and predicted risk of the study cohort, which was triggered by the increasing use of transfemoral aortic valve replacement in our institution in older high risk patients. Noticeably, intra-annularly implantation occurred very frequently. This is triggered by the institutional guideline to implant stentless valves in smaller annuli, which leaves the stented valves for larger annuli, where in turn intra-annularly implantation can be advantageous. This proceeding also led to a predominant male study population, by eliminating female patients with small annuli. Consequently, 64% of valve size 27 mm was implanted intra-annularly.

The early clinical results after implantation of the LDP were within normal limits for bioprostheses. The postoperative course of most patients was uneventful. However, the need of permanent pacemakers in six patients was slightly higher than reported for the SJM Trifecta [7]. Moreover, there were eight patients requiring temporary dialysis postoperatively. However, those patients were multi-morbid and all but one had undergone complex procedures. The 30-day mortality of 2.0% was lower than the EuroSCORE II predicted mortality (3.1 ± 3.9%), which is actually one of the best predictors for hospital mortality after aortic valve replacement [8].

At first glance, hemodynamic data of the LDP in this study were conclusive. Mean results, regarding pressure gradients, EOA and EOAI were comparable or even better than other bioprostheses, like the St. Jude Medical Trifecta, the Sorin Mitroflow, the Medtronic Mosaic or the Sorin Freedom Solo [6, 9–11]. While analyzing these data it´s to consider, that the body surface area of our study population was relatively high (but normal and typical for German inhabitants), which lowered the EOAI results. Additionally, only two cases of severe patient-prosthesis-mismatch were evident. These cases occurred in obese patients with valve size 25 mm, where obesity biased (lowered) the EOAI by causing a higher body surface area. Notably, also 8 of the 21 patients with moderate-patient-prosthesis mismatch were obese (body mass index above 30). But at second glance, hemodynamic outcome with regard to the labelled valve sizes showed conflicting results in comparison to various other available bioprostheses. For this evaluation, data of the 21 mm LDP was not considered, due to the low number of cases. Data for valve-sizes 23 mm and 25 mm were comparable to data published for the SJM Trifecta regarding pressure gradients, EOA and EOAI [7, 12]. In contrast, data for size 27 mm showed inferior results than the SJM Trifecta. The comparison to the Sorin Mitroflow, a stented pericardial bioprostheses, showed comparable pressure gradients for valve-sizes 23 mm and 25 mm, whereas LDP size 27 mm showed higher gradients [9]. The EOAI of the Sorin Mitroflow was lower for all valve sizes, but the gap to the LDP was closest for the 27 mm prosthesis. The Medtronic Mosaic, a stented porcine bioprostheses, showed higher mean pressure gradients for valve sizes 23 mm and 25 mm and comparable values for size 27 mm [10]. Upon consideration of the EOA of the Medtronic Mosaic, values were comparable for valve sizes 23 mm and 25 mm, and higher for size 27 mm [10]. The first generation porcine stentless valves (Medtronic Freestyle, SJM Toronto) showed a clear disadvantage in terms of pressure gradients and EOA [13, 14]. On the contrary, the latest generation of pericardial stentless valves showed lower transvalvular gradients compared to our data [11]. Even so, the EOAI of these valves was only slightly above results of the LDP, but once again with the widest gap for valve size 27 mm [11]. According to the comparison with these studies, valve sizes 23 mm and 25 mm showed excellent hemodynamic properties, while a slightly impaired function of valve size 27 mm was evident. Possibly, the high percentage of intra-annularly implanted valves in this size has an impact, due to the change of the hemodynamic flow pattern caused by the stent in the aortic annulus. However, our results showed no difference between the intra-annular and the supra-annular position for valve size 27, possibly due to the low number of cases. Hence, further studies with larger cohorts and a higher number of implants per size are required. Additionally, longer follow-up is necessary to confirm these findings in mid-term and long-term follow-up.

The Labcor Dokimos Plus was easy to implant, offered operatively no peculiarities and patients showed a satisfactory clinical outcome. Hemodynamic results were pleasing.