No abstract

T he clinical outcome of patients with STsegment elevation myocardial infarction (STEMI) is directly related to the extent of myocardial necrosis.1 Because the extent of necrosis is strongly influenced by the duration of symptoms, time is a key clinical proxy for the stage of evolution of STEMI.2 The length of time from the onset of symptoms is important in strategies for triage and management and for gauging prognosis. Although time from the occurrence of epicardial artery occlusion in a laboratory experimental model can be measured precisely, time from the onset of symptoms is often difficult to accurately estimate because of subjectivity and reliance on recall. Thus, establishing a more reliable method for determining the stage of myocardial infarction (MI) evolution in patients with STEMI would be useful for evaluating the potential for myocardial salvage and guiding clinical management.There is evidence that the assessment of Q waves on the baseline electrocardiogram (ECG) in the region of ST-segment elevation may be a useful predictor of left ventricular dysfunction and outcomes in patients with STEMI given streptokinase within four to six hours of the onset of symptoms. 3,4 Because prior studies of the predictive value of baseline Q waves focused on patients receiving fibrinolytic therapy, we extended this question to a large population of patients with STEMI who were at high risk of adverse clinical outcomes (e.g., death,

Background-Ticagrelor, when compared with clopidogrel, reduced the 12-month risk of vascular death/myocardial infarction and stroke in patients with ST-elevation acute coronary syndromes intended to undergo primary percutaneous coronary intervention in the PLATelet inhibition and patient Outcomes (PLATO) trial. This prespecified ECG substudy explored whether ticagrelor's association with vascular death and myocardial infarction within 1 year would be amplified by (1) the extent of baseline ST shift and (2) subsequently associated with fewer residual ST changes at hospital discharge. Methods and Results-ECGs were evaluated centrally in a core laboratory in 3122 ticagrelor-and 3084 clopidogrel-assigned patients having at least 1 mm ST-elevation in 2 contiguous leads as identified by site investigators on the qualifying ECG.Patients with greater ST-segment shift at baseline had higher rates of vascular death/myocardial infarction within 1 year. Among those who also had an ECG at hospital discharge (nϭ4798), patients with Ն50% ΑST-deviation (ΑST-dev) resolution had higher event-free survival than those with incomplete resolution (6.4% versus 8.8%, adjusted hazard ratio 0.69 (0.54 -0.88), Pϭ0.003). The extent of ΑST-dev resolution was similar irrespective of treatment assignment. The benefit of ticagrelor versus clopidogrel on clinical events was consistent irrespective of the extent of baseline ΑST-dev (P(interaction)ϭ0.728). When stratified according to conventional times from symptom onset, ie, Յ3 hours, 3 to 6 hours, Ͼ6 hours, the extent of baseline ΑST-dev declined progressively over time. As time from symptom onset increased beyond 3 hours, the benefit of ticagrelor appeared to be more pronounced; however, the interaction between time and treatment was not significant (Pϭ0.175). Conclusions-Ticagrelor did not modify ΑST-dev resolution at discharge nor was its benefit affected by the extent of baseline ΑST-dev. These hypothesis-generating observations suggest that the main effects of ticagrelor may not relate to the rapidity or the completeness of acute reperfusion, but rather the prevention of recurrent vascular events by more powerful platelet inhibition or other mechanisms. Clinical Trial Registration-URL: http://www.clinicaltrials.gov. Unique identifier: NCT00391872. (Circulation. 2012;125:514-521.)