Management of Prolonged ST Segment on ECG

Initial Assessment and Interpretation

The European Society of Cardiology recommends that a prolonged ST segment on ECG requires prompt evaluation for acute coronary syndrome, with immediate coronary angiography and reperfusion therapy indicated for patients with clinical signs of ongoing myocardial ischemia, especially when accompanied by ST-segment elevation or depression 1, 2
ST-segment elevation ≥0.1 mV in two contiguous leads (≥0.2 mV in V1-V3) suggests acute coronary occlusion requiring immediate reperfusion therapy, as recommended by the European Heart Journal 1, 3
ST-segment depression ≥0.05 mV in leads V1-V3 may represent posterior myocardial infarction and should be treated as STEMI, according to the European Heart Journal 1, 4

The European Society of Cardiology recommends immediate reperfusion therapy for patients with ST-segment elevation or new/presumed new LBBB, with a preferred approach of emergency coronary angiography with primary PCI 1, 5
For patients with ST-segment depression or T-wave changes, the European Society of Cardiology recommends administering aspirin, clopidogrel, LMWH or unfractionated heparin, beta-blocker, and nitrates, as well as performing serial troponin measurements 7, 3

In patients with LBBB, the European Society of Cardiology recommends looking for concordant ST elevation as an indicator of MI, and considering point-of-care troponin 1-2 hours after symptom onset to decide on emergency angiography 8, 1
For patients with ventricular paced rhythm, the European Society of Cardiology recommends considering reprogramming the pacemaker to evaluate intrinsic rhythm if the patient is not pacemaker-dependent, and urgent angiography may be required to confirm diagnosis 2, 4

The European Society of Cardiology recommends continuing ECG monitoring for at least 24 hours or until an alternative diagnosis is made, and using two-dimensional echocardiography to identify regional wall motion abnormalities that occur within minutes of coronary occlusion 5, 6
Serial troponin measurements are essential for the diagnosis of myocardial infarction, as recommended by the American Heart Association 3, 7

The European Society of Cardiology recommends avoiding the misinterpretation of ST elevation in conditions like left ventricular aneurysm, pericarditis, or benign early repolarization, and recognizing atypical presentations of STEMI, such as isolated posterior MI 1, 4
Delaying reperfusion therapy in patients with new or presumed new LBBB and clinical suspicion of MI should be avoided, as recommended by the European Society of Cardiology 2, 8