Objective To investigate whether grid-tag myocardial strain evaluation can characterise 'border-zone' peri-infarct region and identify patients at risk of ventricular arrhythmia as the peri-infarct myocardial zone may represent an important contributor to ventricular arrhythmia following ST-segment elevation myocardial infarction (STEMI). Methods Forty-five patients with STEMI underwent cardiac magnetic resonance (CMR) imaging on days 3 and 90 following primary percutaneous coronary intervention (PCI). Circumferential peak circumferential systolic strain (CS) and strain rate (CSR) were calculated from grid-tagged images. Myocardial segments were classified into 'infarct', 'borderzone', 'adjacent' and 'remote' regions by late-gadolinium enhancement distribution. The relationship between CS and CSR and these distinct myocardial regions was assessed. Ambulatory Holter monitoring was performed 14 days post myocardial infarction (MI) to estimate ventricular arrhythmia risk via evaluation of heart-rate variability (HRV).
ResultsWe analysed 1,222 myocardial segments. Remote and adjacent regions had near-normal parameters of CS and CSR. Border-zone regions had intermediate CS (-9.0±4.6 vs -5.9± 7.4, P<0.001) and CSR (-86.4±33.3 vs -73.5±51.4, P<0.001) severity compared with infarct regions. Patients with 'borderzone' peri-infarct regions had reduced very-low-frequency power on HRV analysis, which is a surrogate for ventricular arrhythmia risk (P00.03). Conclusion Grid-tagged CMR-derived myocardial strain accurately characterises the mechanical characteristics of 'border-zone' peri-infarct region. Presence of 'border-zone' peri-infarct region correlated with a surrogate marker of heightened arrhythmia risk following STEMI. Key Points • Grid-tagged cardiac magnetic resonance (CMR) offers new insights into myocardial mechanical function. • Grid-tagged CMR identified different characteristics in 'border-zone' and 'adjacent' peri-infarct myocardial regions. • Reduced very-low-frequency (VLF) power is associated with arrhythmic and mortality risk. • The presence of 'border-zone' peri-infarct region correlated with reduced VLF power.
Platelets play a central role in atherothrombosis and subsequent development of acute coronary syndromes (ACS). The understanding of this process has driven a large body of evidence demonstrating the mortality and morbidity benefits of antiplatelet agents in the ACS population. As expected, however, these agents come with an intrinsically increased risk of bleeding which underlies the vast majority of their complications and adverse effects. In today’s setting of compounding comorbidities and broadening indications, finding the balance between thrombosis prevention and bleeding risk remains the challenge for all clinicians considering these medications. This article reviews the current main antiplatelet agents that are available for clinical use and outlines their impact on ACS outcome. We also outline factors which affect the response to these agents and discuss strategies to optimize clinical outcomes.
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