Clinical outcomes of drug-eluting balloon for treatment of small coronary artery in patients with acute myocardial infarction: comment

Abstract

Dear Editor Restenosis has been one of the main limitations after percutaneous coronary interventions (PCI) However, with the use of drug-eluting stents (DES), the risk of this complication has been dramatically reduced by means of very effectively inhibiting neointimal hiperplasia. Drug-coated balloons (DCB), that also reduce neo-intimal hyperplasia, constitute a very effective treatment for in-stent restenosis [1], but results in native coronary vessels have yielded conflicting results [2]. The study by Tan et al. contributes to the evaluation of the effect of DCB in native vessels, specifically in patients with acute myocardial infarction [3]. In their study, clinical events were equivalent between patients treated with DCB and DES [3]. In terms of angiographic outcomes of DCB, this study, as many other studies comparing DCB and DES, has given an important role to late loss, that was comparable between both devices [3]. However, we believe that using late loss is not valid to compare DCB and DES; rather, other angiographic parameters should be used. Binary angiographic restenosis (presence of stenosis severity > 50% at angiographic follow-up) has been the most commonly used angiographic parameter for comparing different techniques used in PCI procedures, such as balloons, stents, and atherectomy devices. Late loss reflects the biological effect (inhibition of neointimal formation) of DES in a very precise way. Also, because of being a continuous variable, has the advantage of necessitating less patients to include in trials comparing the efficacy among different devices. Thus, late loss has been used as a surrogate endpoint in randomized trials to compare DES and bare-metal stents [4] or different types of DES [5]. However, late loss is not valid to compare different types of devices that have different acute gain or late loss, as it occurs between balloons and stents. Late loss is higher after bare-metal stent implantation than after balloon dilatation. Nonetheless, due to its higher acute gain (and also the virtual absence of vessel recoil), binary angiographic restenosis is lower after coronary stenting. Even having similar late loss, DCB may have lower net gain than DES (2). To compare the angiographic outcome after DCB or DES, binary angiographic restenosis or continuous variables other than late loss (i.e. minimum lumen diameter at follow-up or net gain) should be used (Fig. 1).