High on-aspirin treatment platelet reactivity and restenosis after percutaneous coronary intervention: results of the Intracoronary Stenting and Antithrombotic Regimen-ASpirin and Platelet Inhibition (ISAR-ASPI) Registry

OBJECTIVE

The aim of this study was to assess the association between high on-aspirin treatment platelet reactivity (HAPR) and the subsequent risk of restenosis after percutaneous coronary intervention (PCI) with predominantly drug-eluting stents.

BACKGROUND

The association between HAPR and subsequent risk of restenosis after PCI is unclear.

METHODS

This study included 4839 patients undergoing PCI (02/2007-12/2011) in the setting of the Intracoronary Stenting and Antithrombotic Regimen-ASpirin and Platelet Inhibition (ISAR-ASPI) registry. Platelet function was assessed with impedance aggregometry using the multi-plate analyzer immediately before PCI and after intravenous administration of aspirin (500 mg). The primary outcome was clinical restenosis, defined as target lesion revascularization at 1 year. Secondary outcomes included binary angiographic restenosis and late lumen loss at 6- to 8-month angiography.

RESULTS

The upper quintile cut-off of platelet reactivity measurements (191 AU × min) was used to categorize patients into a group with HAPR (platelet reactivity > 191 AU × min; n = 952) and a group without HAPR (platelet reactivity ≤ 191 AU × min; n = 3887). The primary outcome occurred in 94 patients in the HAPR group and 405 patients without HAPR (cumulative incidence, 9.9% and 10.4%; HR = 0.96, 95% CI 0.77-1.19; P = 0.70). Follow-up angiography was performed in 73.2% of patients. There was no difference in binary restenosis (15.2% vs. 14.9%; P = 0.79) or late lumen loss (0.32 ± 0.57 vs. 0.32 ± 0.59 mm; P = 0.93) between patients with HAPR versus those without HAPR.

CONCLUSIONS

This study did not find an association between HAPR, measured at the time of PCI, and clinical restenosis at 1 year after PCI.

Comparison of Vascular Closure Devices vs Manual Compression After Femoral Artery Puncture in Patients on Oral Anticoagulation - Post Hoc Analysis of the ISAR-CLOSURE Trial

OBJECTIVES

To compare vascular closure devices (VCD) with manual compression (MC) in patients on chronic oral anticoagulation (OAC) who undergo diagnostic coronary angiography in terms of vascular access-site complications.

METHODS

This is a subanalysis of 604 patients that had undergone transfemoral diagnostic coronary angiography and were randomly assigned to arteriotomy closure with either VCDs (intravascular FemoSeal VCD or extravascular EXOSEAL VCD) or MC within the large scale, randomized ISAR-CLOSURE trial. Primary endpoint was the composite of access-site-related vascular complications at 30 days. Secondary endpoints were time to hemostasis and repeat MC.

RESULTS

Vascular access-site complications were similar in patients assigned to VCDs compared to MC (8.2% vs 10.6%; P=.33). There was no interaction of treatment effect and OAC (P interaction = 0.59). Rates of pseudoaneurysms were lower with VCDs (0.8% vs 3.2%; P=.02). Time to hemostasis was significantly shortened with VCDs compared to MC (1 [IQR 0.5-2.0] min vs 12 [IQR 10-15] min; P<.001). There was no difference regarding repeat MC in both groups (VCD 1.5% vs MC 0.5%; P=.23). Time to hemostasis (0.5 [0.2-1.0] min, vs 2.0 [1.75-2.0] min; P<.001) and closure device failure (3.7% vs 17.2%; P<.001) were lower with the intravascular VCD, compared with the extravascular VCD.

CONCLUSIONS

In patients on chronic OAC undergoing transfemoral diagnostic coronary angiography, the use of VCDs was comparable to MC regarding the primary combined endpoint of vascular access-site related complications. VCDs reduced the occurrence of pseudoaneurysms and time to hemostasis.

Ticagrelor or Prasugrel in Patients with Acute Coronary Syndromes

BACKGROUND

The relative merits of ticagrelor as compared with prasugrel in patients with acute coronary syndromes for whom invasive evaluation is planned are uncertain.

METHODS

In this multicenter, randomized, open-label trial, we randomly assigned patients who presented with acute coronary syndromes and for whom invasive evaluation was planned to receive either ticagrelor or prasugrel. The primary end point was the composite of death, myocardial infarction, or stroke at 1 year. A major secondary end point (the safety end point) was bleeding.

RESULTS

A total of 4018 patients underwent randomization. A primary end-point event occurred in 184 of 2012 patients (9.3%) in the ticagrelor group and in 137 of 2006 patients (6.9%) in the prasugrel group (hazard ratio, 1.36; 95% confidence interval [CI], 1.09 to 1.70; P = 0.006). The respective incidences of the individual components of the primary end point in the ticagrelor group and the prasugrel group were as follows: death, 4.5% and 3.7%; myocardial infarction, 4.8% and 3.0%; and stroke, 1.1% and 1.0%. Definite or probable stent thrombosis occurred in 1.3% of patients assigned to ticagrelor and 1.0% of patients assigned to prasugrel, and definite stent thrombosis occurred in 1.1% and 0.6%, respectively. Major bleeding (as defined by the Bleeding Academic Research Consortium scale) was observed in 5.4% of patients in the ticagrelor group and in 4.8% of patients in the prasugrel group (hazard ratio, 1.12; 95% CI, 0.83 to 1.51; P = 0.46).

CONCLUSIONS

Among patients who presented with acute coronary syndromes with or without ST-segment elevation, the incidence of death, myocardial infarction, or stroke was significantly lower among those who received prasugrel than among those who received ticagrelor, and the incidence of major bleeding was not significantly different between the two groups. (Funded by the German Center for Cardiovascular Research and Deutsches Herzzentrum München; ISAR-REACT 5 ClinicalTrials.gov number, NCT01944800.).

Revacept, a Novel Inhibitor of Platelet Adhesion, in Patients Undergoing Elective PCI-Design and Rationale of the Randomized ISAR-PLASTER Trial

Despite dual antiplatelet therapy patients undergoing percutaneous coronary intervention (PCI) continue to experience periprocedural ischemic events. In addition, all currently used antithrombotic drugs increase the bleeding risk. Thus, there is an unmet clinical need for antithrombotic strategies with improved efficacy and no increase in bleeding. Revacept is a novel, lesion-directed antithrombotic drug that does not interfere with the function of circulating platelets. This dimeric fusion protein of the extracellular domain of glycoprotein VI (the major platelet collagen receptor) and the human Fc-fragment inhibits collagen-mediated platelet adhesion and subsequent aggregation at the site of vascular injury. The randomized, double-blinded, phase II ISAR-PLASTER trial is based on extensive preclinical evaluation of Revacept and a favorable first-in-man trial. A total of 332 patients with stable coronary artery disease undergoing elective PCI will be randomized to either Revacept 160 mg, Revacept 80 mg, or placebo administered as single intravenous infusion directly before the intervention, on top of standard dual antiplatelet therapy and either heparin or bivalirudin, based on local practice and current guidelines. The primary endpoint is the composite of death or myocardial injury (defined as increase in high sensitivity troponin T ≥ 5 times the upper limit of normal) at 48 hours. The safety endpoint is bleeding of class 2 or higher according to the Bleeding Academic Research Consortium at 30 days. This phase II randomized, double blind trial will assess for the first time the efficacy and safety of Revacept-a lesion-directed inhibitor of platelet adhesion-in patients undergoing elective PCI.

Correlation of optotypes with the Landolt ring--a fresh look at the comparability of optotypes

The legibility of three selected sets of optotypes: (1) letters; (2) Snellen E; and (3) KOLT test have been compared to the Landolt ring in a study based on the German Standard DIN 58220, Part 2 and the International Standard ISO 8597. The letters were printed in the standard typeface used on German street signs (sans serif Linear-Antiqua, Typeface B). The main results are: 1. A set of letters can be selected in such a way that the differences in legibility displayed between different letters in the set are smaller than the ISO/DIN allowance of 0.05 logarithmic units of the visual angle, although the letters are not constructed according to the traditional 5 by 5 or 5 by 4 construction principles. 2. The eight letters C, D, E, K, N, P, U, Z are proposed for standardized visual acuity tests because of their almost equal legibility. 3. The height of the typeface used for this selected set of letters should be 5% less than the diameter of the Landolt ring in order to achieve the same legibility as the latter. 4. Both shape optotypes (Snellen E and KOLT test) must be approximately 15% smaller than the diameter of the Landolt ring in order to obtain comparable visual acuity scores.

Amblyopic processing of positional information. Part I: Vernier acuity

Psychometric functions for the recognition of vernier displacements have been measured in 6 strabismic amblyopes, 1 anisometropic amblyope, and 1 bilateral amblyope of unknown aetiology. In the non-amblyopic eyes of the 7 unilateral amblyopes the mean threshold vernier offset was about half of that of a group of 7 experienced normal observers. No correlation was found between vernier acuities and Snellen acuities in the abnormal eyes of squinters. These eyes also displayed massive distortions of horizontal spatial values causing perceptual distortions. In all but one of the amblyopic eyes tested hyperacuity virtually disappeared at the brief exposure duration of 50 ms. None of the observed effects could be predicted from the amblyopic contrast sensitivities, grating resolutions, or letter acuities. This suggests that the loss of positional information is an independent and most significant feature of amblyopic visual dysfunction.

Discrimination thresholds in the two-dimensional spatial frequency domain

In two experiments we have determined the discriminability between two sinusoidal gratings as a function of orientation and spatial frequency differences. Twelve orientation (15 degrees steps) and four spatial frequencies (2, 4, 8, 12 c/deg) were considered and corresponding discrimination thresholds were determined. Results indicated that: (a) spatial frequency discrimination thresholds did not significantly vary over all frequency and orientation positions, and averaged at +/- 1/8 octave limits. (b) Orientation thresholds only slightly increased with spatial frequency (from +/- 5 degrees at 2 c/deg to +/- 6 degrees at 12 c/deg). (c) A large and consistent anisotropy occurred with orientation thresholds showing most sensitivity in the horizontal and vertical directions, with largest thresholds at the oblique angles. No oblique effect was observed with spatial frequency thresholds. These results confirm past observations, providing an extensive set of threshold measurements in the two-dimensional spatial domain.

Modelling perceptual distortion: amplitude and phase transmission in the human visual system

In this paper we consider the complementary properties of image amplitude and phase components and their role in normal and amblyopic vision. Specific two-dimensional filtered images are included to demonstrate the possible perceptual distortions due to both amplitude and phase disturbances. Finally, the relationships between amplitude and phase filters are discussed with reference to the types of receptive field distributions expected to underly the normal and abnormal cases.

Illusions of filled lateral and angular extent. The role of cortical feature detectors

The common principle of the illusions found by Helmholtz and Botti is the overestimation of a filled extent. They differ in that Helmholtz's illusions of filled angular extent can be accounted for in terms of spatial two-line interactions, whereas Botti's illusions of filled lateral extent cannot. The former observation is consistent with the assumption of interacting orientation-detectors in the visual cortex. The Botti illusion probably depends on global computation in the visual system.

Insensitivity of peripheral vision to spatial phase

Tolhurst (1973) had suggested that movement-sensitive mechanisms were the human analogues of transient (Y) neurones in the cat (Enroth-Cugell and Robson 1966) and monkey (Gouras 1968) visual system. We challenged this view in a previous study (Rentschler et al. 1981): in strabismic amblyopia the detection of apparent movement of counterphased gratings is impaired considerably more than pattern detection, whereas no such anomaly is found when the sensitivity to temporal transients is tested. This would imply that with a grating target the detection of lateral movement and of transients is not mediated by the same class of mechanisms. Moreover, we have shown that normal peripheral vision suffers qualitatively from the same kind of movement insensitivity as the amblyopic eye. In this study, we have used a wider range of stimulus parameters to seek more definite evidence.

Amblyopic abnormality involves neural mechanisms concerned with movement processing

In strabismic amblyopia the detection of apparent movement for counterphase gratings is considerably more impaired than the detection of pattern. No such anomaly is found for the detection of changes from a blank field when gradual or abrupt onsets or offsets of the temporal grating presentation are used. Similarly, normal peripheral vision is relatively poor in detecting alternation of spatial phase. It is concluded that the observed movement abnormality does not reflect a loss in sensitivity of transient mechanisms but rather a visual insensitivity to spatial phase. This would explain why perceptual distortions and low optotype acuity occur in amblyopes with normal contrast sensitivity.

Spatial tuning properties in human amblyopia cannot explain the loss of optotype acuity

Strabismic amblyopes may exhibit in their squinting eye an almost normal contrast sensitivity to gratings although their optotype acuity is strongly impaired. This discrepancy cannot be accounted for by reduced selectivity of spatial-frequency channels or line-sensitivity functions. Alternative explanations for the loss of letter visual acuity as abnormal interactions between psycho-physical detector-mechanisms or defects in spatial phase sensitivity are discussed.

Abnormal orientation selectivity in both eyes of strabismic amblyopes

In normal observers preadaptation to a parallel grating increases the contrast threshold for a line whereas a perpendicular grating has no effect. Such orientation selectivity was not found in the amblyopic eye of two out of five squinters. Only a weak after-effect produced with a grating parallel to the line was obtained in the good eye of four of the amblyopes while all of them show an abnormal threshold reduction following adaptation to a perpendicular grating. This suggests a relationship between abnormal binocular interaction during visual development and the organization of orientational mechanisms but does not explain the loss of visual acuity in amblyopia.

[Improvement of visual acuity in lens opacities using an optic aperture (author's transl)]

A diaphragm, placed in front of the eye acts as an artificial pupil as well as a field stop. The improvement of visual performance in the presence of opacities is due to its action as a field stop.