Coronary and structural interventions: novel evidence for decision making

For the podcast associated with this article, please visit https://academic.oup.com/eurheartj/pages/Podcasts The introduction of stents or scaffolds to stabilize intimal dissections and prevent acute coronary occlusions after balloon angioplasty was a major step forward for percutaneous coronary interventions or PCI.1 Although the introduction of drug-eluting stents further optimized the technology,2,3 disadvantages remained: first, these metallic cages prevent physiological coronary vasomotion4,5 and, secondly, they hinder or even prevent later bypass graft insertions for those in need. Finally, many patients would prefer that stents would not remain in their heart forever, but just for the peri-interventional period. Thus, the concept of bioabsorbable scaffolds was developed. The first of its class, the Absorb® stent6,7 was welcomed by many operators and patients alike. However, recent larger trials reported a markedly higher acute and late stent thrombosis rate with this particular scaffold.8,9 As a consequence, bioabsorbable scaffolds are currently only available in research protocols and trials. The executive summary of the ‘Report of an ESC-EAPCI Task Force on the evaluation and use of bioresorbable scaffolds for percutaneous coronary intervention’10 by Robert A. Byrne and colleagues addresses this issue. Following a dialogue with the European Commission, they were asked to prepare a report on bioresorbable scaffolds. Five bioresorbable scaffolds have CE-mark approval for use in Europe. Only one device—the Absorb®—has been tested in randomized trials, with an inferior outcome compared with metallic drug-eluting stents. The Task Force recommends that new bioresorbable scaffold devices should undergo systematic non-clinical testing prior to evaluation in clinical studies. A clinical evaluation should involve a medium-sized, randomized trial against drug-eluting stents powered for surrogate endpoints of efficacy. Successful devices will receive the CE-mark and must have an approved plan for a large-scale randomized clinical trial with long-term follow-up. Local haemodynamic forces such as endothelial shear stress influence atherosclerosis and plaque formation11,12 as well as vascular healing as implanted bioabsorbable scaffolds dissolve.13 In their manuscript entitled ‘Endothelial shear stress 5 years after implantation of a coronary bioresorbable scaffold’,14 Patrick W. Serruys and colleagues from Imperial College, London, UK performed serial computational fluid dynamic simulations to examine immediate and long-term haemodynamic and vascular changes following bioresorbable scaffold implantation. Coronary arterial models at baseline and 5 years were reconstructed through fusion of intravascular optical coherence tomography and angiography. A marked heterogeneity in endothelial shear stress and localized regions of high blood viscosity were observed post-implantation. The percentage of vessel area exposed to low endothelial shear stress significantly decreased over 5 years, whereas moderate and high endothelial shear stress did not change, leading to higher endothelial shear stress at follow-up (Figure 1). A positive correlation was observed between baseline endothelial shear stress and change in lumen area, and maximum blood viscosity decrease over 5 years. Thus, immediately after scaffold implantation, coronary arteries demonstrate an alternans of extremely low and high endothelial shear stress values and localized areas of high blood viscosity. These initial local haemodynamic disturbances may trigger fibrin deposition and thrombosis. Also, low endothelial shear stress can promote neointimal hyperplasia, but may also contribute to appropriate scaffold healing with normalization of endothelial shear stress and reduction in peak blood viscosity. Histogram demonstrating the percentage of the lumen area exposed to various levels of endothelial shear stress at baseline and 5 years for each case (from Thondapu V, Tenekecioglu E, Poon EKW, Collet C, Torii R, Bourantas CV, Chin C, Sotomi Y, Jonker H, Dijkstra J, Revalor E, Gijsen F, Onuma Y, Ooi A, Barlis P, Serruys PW. Endothelial shear stress 5 years after implantation of a coronary bioresorbable scaffold. See pages 1602–1609). Kaplan–Meier curves for clinical outcomes in the overall population (from Kang D-Y, Ahn J-M, Lee CH, Lee PH, Park D-W, Kang S-J, Lee S-W, Kim Y-H, Lee CW, Park S-W, Park S-J. Deferred vs. performed revascularization for coronary stenosis with grey-zone fractional flow reserve values: data fromthe IRIS-FFR registry. See Pages 1610–1619). Obviously, PCI should only be performed in lesions causing ischaemia. Traditionally, this has been assessed by eye balling and later non-invasive nuclear imaging,15,16 then cardiac magnetic resonance imaging17 and, most recently, coronary computed tomography.18,19 All these approaches have their downsides and thus intracoronary pressure measurements have been introduced, i.e. fractional flow reserve or FFR.20–22 The optimal cut-off FFR value for revascularization, however, is still debated. In their article entitled ‘Deferred vs. performed revascularization for coronary stenoses with grey-zone fractional flow reserve values: data from the IRIS-FFR Registry’23 Seung Jung Park and colleagues from the ASAN Medical Center in Seoul, Republic of Korea evaluated the prognosis for deferred and performed revascularization in coronary stenoses with FFR values in the grey zone, i.e. 0.75–0.80 in 1334 patients. Revascularization was deferred in 683 and performed in 651 patients. After 2.9 years, the primary outcome of target vessel infarction and target vessel revascularization occurred in 8.1% in the deferred and 8.4% in the performed group (interquartile range, 1.5–4.1 years). Overall mortality and spontaneous myocardial infarction did not differ either, mainly because of a higher risk of peri-procedural infarction. However, target vessel revascularization was significantly higher in the deferred group (5.7% vs. 3.7%). Thus, in coronary stenoses within the grey-zone FFR, revascularization was not associated with better clinical outcomes. The higher likelihood of peri-procedural myocardial infarction with revascularization was offset by the higher likelihood of target vessel revascularization with deferral. These clinically highly relevant results are further discussed in an Editorial by Nils P. Johnson from the University of Texas Medical School at Houston in the USA.24 Besides the design of stents and lesion characteristics, interventional skills and operator experience25 are important predictors of outcomes for PCI. Although this has been reported previously, changing case mix, practice, and service provision over the last years may have changed volume–outcome relationships. In their analysis entitled ‘Operator volume is not associated with mortality following percutaneous coronary intervention: insights from the British Cardiovascular Intervention Society registry’,26 Chun Shing Kwok and colleagues from the Keele University in Stoke-on-Trent, UK determined whether operator volume is associated with 30-day mortality in the British Cardiovascular Intervention Society Percutaneous Coronary Intervention database of 13 970 procedures. Median volume was 178 per year, with a 30-day mortality of 2.6%. After adjustment, sensitivity analyses showed similar results amongst high-risk PCI subsets and in-hospital outcomes. Thus, in current clinical practice with substantial median procedure numbers, there is no evidence that mortality differs by operator volume. These provocative findings are put into context in a thought-provoking Editorial by Davide Capodanno from the University of Catania in Italy.27 A patent foramen ovale might allow a venous thrombus to pass into the arterial circulation and cause a stroke.28 However, the efficacy of patent foramen ovale closure for cryptogenic stroke has been controversial. Indeed, while some trials confirmed protection,29 others missed their primary endpoint.30 Recently, the publication of large trials31,32 has changed the evidence base substantially. In their meta-analysis ‘Patent foramen ovale closure vs. medical therapy for cryptogenic stroke: a meta-analysis of randomized controlled trials’, Yousif Ahmad and colleagues from the Imperial College London in the UK compared device closure with medical therapy to prevent recurrent stroke for patients with patent foramen ovale using the current data.33 Overall, 1829 patients were randomized to device closure and 1611 to medical therapy. Patent foramen ovale closure was superior to medical therapy for prevention of stroke, with an impressive hazard ratio of 0.32. However, the risk of atrial fibrillation was also significantly increased with device closure, with a hazard ratio of 4.54. In patients with large shunts, device closure significantly reduced stroke (hazard ratio 0.33), whilst there was no significant reduction in stroke in those with a small shunts. There was no effect of an atrial septal aneurysm on outcomes. Thus, in selected patients with cryptogenic stroke and a large shunt, patent foramen ovale closure is superior to medical therapy for secondary prevention of stroke. Guidelines should therefore be updated, as further discussed in an Editorial by Bernhard Meier from the University Hospital Bern and Fabian Nietlispach from the University Hospital Zurich, Switzerland.34 Finally, this Focus Issue on Interventional Cardiology contains the first two Discussion Forum contributions related to a previously published manuscript entitled ‘Prevalence and prognostic significance of negative U-waves in a 12-lead electrocardiogram in the general population’ authored by Arttu Holkeri and colleagues from the Helsinki University Hospital in Finland.35 Michael Gurven and colleagues from the University of California Santa Barbara in California (USA) comment on this publication,36 and Holkeri et al. respond.37 The editors hope that this issue of the European Heart Journal will be of interest to its readers.