Spatial orientation of cross-sectional images of coronary arteries: point of view in intracoronary imaging

<p>Abstract</p> <p>Background</p> <p>In studies where cross-sectional images of coronary arteries obtained with different imaging modalities are compared, the importance of correct co-localization and matching of images along the coronary artery longitudinal axis is obvious. However, it appears neglected that correct spatial orientation of the cross-sectional plane may not be obtainable just by rotating the images to ensure co-localization of identifiable landmarks such as sidebranches. A cross-section has two sides, one facing proximally and the other distally, and pairs of images reconstructed corresponding to these opposite points of view are mirror images of each other and not superimposable. This may be difficult if not impossible to recognize and unrecognized it will give rise to flawed results in the development and validation of imaging technologies aimed at plaque characterization (tissue mapping). We determined the imagined point of view for three commercially available intracoronary imaging systems used by invasive cardiologists and illustrate its importance in imaging modality validation.</p> <p>Methods and Results</p> <p>We made an asymmetric phantom and investigated it with two different intravascular ultrasound (IVUS) systems and one optical coherence tomography (OCT) system. The asymmetry of the phantom allowed determination of the spatial orientation of the cross-sectional images. On all tested systems, an observer should imagine herself/himself standing proximal to the cross-section when looking at the intravascular images.</p> <p>Conclusions</p> <p>The tested intracoronary imaging modalities displayed cross-sectional images with a spatial orientation corresponding to a proximal point of view. Knowledge of the spatial orientation is mandatory when comparing and validating different imaging modalities aimed at plaque characterization.</p

Effectiveness and Safety of Ticagrelor Implementation in Patients with Acute Coronary Syndrome undergoing Percutaneous Coronary Intervention:A Cohort Study in Western Denmark

BACKGROUND: Ticagrelor was introduced in Denmark in 2011 after randomised data showed its superiority over clopidogrel for patients with acute coronary syndrome (ACS). We assessed the effectiveness and safety of ticagrelor implementation in ACS patients undergoing percutaneous coronary intervention (PCI). METHODS: We identified PCI-treated ACS patients in Western Denmark who redeemed a P2Y12 inhibitor prescription within 14 days. Using Danish health registries, 1-year outcomes were compared before (2007-2010) and after (2012-2015) introduction of ticagrelor. Outcomes were MACE (death, myocardial infarction, and ischaemic stroke) and hospitalisation for bleeding. Inverse probability of treatment weights were used to estimate weighted incidence rate ratios (wIRRs). FINDINGS: We included 14,450 patients; 7,102 were treated in the earlier time period (99·9% clopidogrel) and 7,348 in the later time period (87·8% ticagrelor). Ticagrelor implementation was not associated with a clinically relevant difference in 1-year risk of MACE with 413 events in the ticagrelor period vs. 424 events in the clopidogrel period (cumulative incidence percentage [CIP] 5·6% vs. 6·0%; wIRR 1·06, 95% CI 0·92-1·22). The 1-year risk of bleeding was also similar between groups with 335 bleedings requiring hospitalisation in the ticagrelor period vs. 309 events in the clopidogrel period (CIP 4·6% vs. 4·4%; wIRR 1·05, 95% CI 0·89-1·23). Results were robust in patients above and below 70 years of age. INTERPRETATION: Implementation of ticagrelor was not associated with changes in risks of ischaemic or bleeding events in Danish PCI-treated ACS patients