Is bioprosthetic leaflet thrombosis a trigger to valve degeneration?

Is bioprosthetic leaflet thrombosis a trigger to valve degeneration?

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Transcatheter aortic valve implantation (TAVI) has expanded quickly as a novel therapeutic technique for sufferers with extreme symptomatic aortic stenosis. This process is already nicely established in sufferers at intermediate or excessive threat for standard surgical valve substitute and, with a number of research at the moment evaluating TAVI in low-risk sufferers, use of this therapy is prone to proceed to develop worldwide. Whereas long-term final result knowledge are missing, current outcomes from the Placement of Aortic Transcatheter Valves (PARTNER) trial indicated promising outcomes at 5 years post-implantation, with TAVI valves demonstrating related haemodynamics to surgical bioprosthetic valves and no proof of structural valve deterioration on echocardiography.1 Regardless of these promising knowledge, long-term TAVI sturdiness and the mechanisms resulting in structural valve degeneration will not be absolutely understood. Enhancing our understanding of valve sturdiness and the components resulting in TAVI valve deterioration is subsequently paramount, notably as we think about extending this know-how to youthful affected person populations.

Of their Coronary heart manuscript, Del Trigo et al
2 examine the connection between using anticoagulation remedy and valve haemodynamic deterioration in over 2000 sufferers post-TAVI. On this cohort, 707 sufferers have been handled with oral anticoagulation remedy with the commonest indication being atrial fibrillation. The bulk obtained vitamin Ok antagonists, with solely a small proportion handled with direct oral anticoagulants. At 1 12 months follow-up, a small however important improve in imply transvalvular gradient on transthoracic echocardiography was noticed in sufferers not receiving anticoagulation (9.eight mm Hg to 10.three mm Hg) in contrast with post-discharge values. In contrast, transvalvular gradients remained steady after 1 12 months within the sufferers receiving anticoagulation (9.four mm Hg and 9.1 mm Hg). Valve haemodynamic deterioration, outlined as a rise in transvalvular gradient of ≥10 mm Hg from hospital discharge, had the next incidence within the group not handled with anticoagulation in contrast with these receiving anticoagulation (three.7% vs zero.6%, P<zero.001). This was noticed each within the inhabitants as an entire and in a propensity-matched cohort.

This research does have some limitations. The cohort largely comprised sufferers with well-functioning valves, certainly even these sufferers identified with valve haemodynamic deterioration had solely gentle bioprosthetic stenosis, with transvalvular gradients <40 mm Hg. As a consequence, there have been too few hostile scientific occasions in sufferers with valve haemodynamic deterioration within the matched inhabitants (n=7) for significant evaluation. One other essential limitation is that bleeding charges on this cohort weren’t out there, and it’s subsequently not attainable to stability the obvious advantages of anticoagulation on valve sturdiness towards the danger of main bleeding. Lastly, this isn’t a randomised managed trial and there’ll subsequently be each recognized and unknown confounders that may account for the noticed variations.

Nonetheless, the authors are to be congratulated on investigating this essential space and highlighting the intriguing speculation that anticoagulation remedy post-TAVI could shield towards subsequent valve deterioration. This requires a transparent mechanistic rationalization. Bioprosthetic valve degeneration is predominantly pushed by calcification: how would possibly this be linked to antithrombotic remedy? One potential reply is valve leaflet thrombosis. Whereas leaflet thrombosis inflicting abrupt valve failure happens in simply 1% of TAVI valves, subclinical valve thrombosis has been noticed in 7%–10% of implanted TAVI valves.three four The scientific relevance of this imaging commentary has to this point been unclear, however maybe this isn’t a benign phenomenon, maybe valve leaflet thrombosis acts as a set off to calcification and finally TAVI valve degeneration (determine 1). This speculation is supported by the pathophysiology of native aortic valve stenosis the place valve leaflet haemorrhage is related to extra fast valve calcification and illness development.5 The research by Del Trigo et al is subsequently essential due to the important thing mechanistic questions raised. Within the absence of anticoagulation, do bioprostheses with proof of leaflet thrombosis calcify and degenerate extra shortly? Can histological or imaging research verify the affiliation between leaflet thrombosis and early calcification exercise? Are surgical bioprostheses additionally vulnerable to related mechanisms of degeneration? Analysis should now concentrate on gaining a larger understanding of the hyperlink between valve thrombosis and degeneration, with the hope that finally this can assist inform optimum administration to extend bioprosthetic valve longevity and enhance affected person outcomes.

Figure 1
Determine 1

Attainable hyperlink between bioprosthetic valve thrombosis and calcification. The research by Del Trigo et al means that anticoagulation could protect transcatheter aortic valve implantation (TAVI) valve haemodynamics. The potential mechanism for this commentary shouldn’t be clear. Concern has lately grown relating to the incidence of subclinical leaflet thrombosis (crimson arrow) in sufferers present process TAVI, and it’s hypothesised that this will result in future calcific degeneration of bioprosthetic TAVI valves (black arrow). Future analysis ought to concentrate on investigating this attainable mechanistic hyperlink between bioprosthetic leaflet thrombosis and valve calcification/degeneration and the function that anticoagulant remedy would possibly play in bettering TAVI valve sturdiness. 

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