Aortic valve replacement with mechanical prosthesis in small aortic annulus: Keep it simple!

Abstract

We read with great interest the systematic review from Agarwal and colleagues, comparing the results of sutureless valves versus conventional aortic valve replacement (AVR) with aortic root enlargement in patients with aortic stenosis and small aortic annulus. We herein comment on the review trying to highlight some major issues. Based on some recent literature's evidences and on the authors’ personal experience, we suggest to consider AVR with mechanical valve as a still viable option, especially in small aortic annulus. Indeed, root enlargement techniques are not always easy to perform and sutureless valve is still burdened by higher rate of PM implantation.

To the Editor,

We read with great interest the systematic review from Agarwal and colleagues, ¹ comparing the results of sutureless valves (SVs) versus conventional aortic valve replacement (AVR) with aortic root enlargement (ARE) in patients with aortic stenosis and small aortic annulus. The concept of patient-prosthesis mismatch (PPM) avoidance in AVR has been advocated by several authors in order to improve Left Ventricle (LV) hypertrophy regression and to maximize clinical outcomes. ² Furthermore, ARE techniques are living a renewed popularity, especially in younger age, in order to accommodate larger bioprosthesis sizes for future Transcatether Aortic Valve Replacement (TAVR) valve-in-valve strategy in case of structural valve degeneration. However, we raised some concerns in the author’s review. First of all, the two groups of patients are significantly different in terms of age and clinical presentation (Heart Failure (HF) symptoms and associated coronary artery disease). Particularly, given the difference between the mean ages in both groups (78.9 vs 61.9 years in SV and ARE groups, respectively) any consideration regarding early and late outcomes is, in our opinion, meaningless, and can be hardly related to the surgical technique. Secondly, if we look at the perioperative results (in-hospital mortality = 3.8%; reexploration for bleeding = 5%) in the ARE group, they seem worse than expected, probably suggesting that AVR with annulus enlargement is not an uncomplicated procedure and perhaps is not easily reproducible in everyone's hands. Finally, despite the use of SV in small aortic roots, postoperative moderate, and severe PPM was still evident in nearly 34% and 11% of patients, respectively. Several factors in recent years (patients’ preferences, market influences, and TAVR fast growing) have pushed the cardiovascular community toward considering bioprosthesis implantation as the “Holy Grail” of valve replacement, not only in older patients but also in younger age. However, we think that mechanical AVR should be still included in the therapeutic possibilities. Indeed, recent studies suggested that in patients aged between 54 and 65 years, AVR with mechanical valve is associated with a survival benefit compared to bioprosthesis, ³ and several trials of low-INR and self-anticoagulation management demonstrated excellent early and long-term outcomes for mechanical valve recipients. ⁴ Small diameter mechanical bileaflets prosthesis have excellent hemodynamic even in small aortic root, especially when implanted in supra-annular position, and can be easily implanted thus avoiding long and complex procedures. Our group in a consecutive series of AVR with 17-mm mechanical valve, showed excellent early and long-term outcomes, with significant reduction of transprosthesis gradients, LV mass regression, and functional improvement. ⁵ We believe that in the current era, every single patient requires careful discussion and a tailored approach. Particularly, middle age patients should be carefully evaluated, considering that mechanical prosthesis conveys a definitive solution with survival benefit, while inadequate AVR with bioprosthesis exposes the patient to further complex procedure, including suboptimal VIV that requires complex technical issues like bioprosthesis fracture or chimney technique.