The electrocardiogram (ECG) at presentation is a useful tool for risk prediction. Patients with ACS（Acute Coronary Syndromes） and ST-segment depression on ECG have a worse prognosis than patients with a normal ECG. ST-segment depression is not only a qualitative marker, but also a quantitative marker of risk, because the number of leads with ST-segment depression and the magnitude of ST-segment depression (either within a single lead or as sum over all leads) are indicative of the extent of ischaemia and correlate with prognosis.The presence of ST-segment depression >1 mm in >_6 leads in conjunction with ST-segment elevation in aVR and/or V1, particularly if the patient presents with haemodynamic compromise, suggests multivessel ischaemia or severe left main coronary artery stenosis. However,in patients presenting without persistent ST-segment elevation,the clinical features, treatments, and outcomes in patients with normal ECG is still unclear.
the investigators aimed to analyzed data for hospitalized MI patients with normal ECG.