Guideline Recommendations for Immediate Management of ST‑Segment Depression in Acute Coronary Syndrome

Immediate Pharmacologic Therapy

Dual antiplatelet therapy should be started immediately – give aspirin (75–150 mg orally or IV if unable to swallow) plus a P2Y12 inhibitor (ticagrelor or prasugrel) together with anticoagulation; very‑high‑risk patients require coronary angiography within 2 hours. – European Society of Cardiology (ESC) guideline 1
Aspirin 75–150 mg PO (or IV) should be administered at presentation unless contraindicated. – ESC guideline 3
Ticagrelor 180 mg loading dose followed by 90 mg twice daily is recommended for all moderate‑to‑high‑risk patients with elevated troponin, irrespective of the planned invasive strategy. – ESC guideline 4
Prasugrel 60 mg loading dose is advised when proceeding to PCI in patients < 75 years, weight > 60 kg, and without prior stroke/TIA. – ESC guideline 1
Clopidogrel 300–600 mg loading dose may be used only when ticagrelor or prasugrel are unavailable or contraindicated. – ESC guideline 2
Anticoagulation – low‑molecular‑weight heparin (enoxaparin preferred) or unfractionated heparin should be given and continued until revascularisation or hospital discharge. – ESC guideline 3
Beta‑blockers and nitrates (oral or IV) are indicated for ongoing or recurrent chest pain. – ESC guideline 3

Anterior (V1‑V4) ST‑segment depression may mask posterior STEMI; an immediate posterior‑lead ECG should be obtained to avoid missing a STEMI equivalent. – ESC guideline 5
Posterior wall STEMI identified by posterior leads requires urgent reperfusion as a STEMI equivalent. – ESC guideline 7
High‑sensitivity cardiac troponin should be drawn at presentation; repeat at 1–2 h (high‑sensitivity assay) or 3–6 h (conventional assay) to detect dynamic changes. – ESC guideline 6
Dynamic ST‑segment changes together with troponin rise define high‑risk NSTE‑ACS and trigger early invasive evaluation. – ESC guideline 1

Hemodynamic instability or cardiogenic shock – ESC guideline 4
Recurrent or ongoing chest pain refractory to medical therapy – ESC guideline 4
Life‑threatening arrhythmias or cardiac arrest – ESC guideline 1
Mechanical complications of myocardial infarction – ESC guideline 1
Acute heart failure with refractory angina or persistent ST deviation – ESC guideline 3

A rise or fall in cardiac troponin compatible with myocardial infarction – ESC guideline 3
GRACE risk score > 140 – ESC guideline 9

Diabetes mellitus – ESC guideline 9
Renal insufficiency (eGFR < 60 mL/min/1.73 m²) – ESC guideline 9
Left‑ventricular ejection fraction < 40 % or overt congestive heart failure – ESC guideline 5
Early post‑infarction angina – ESC guideline 9
Recent PCI or prior coronary‑artery bypass grafting – ESC guideline 10
GRACE score 109–140 – ESC guideline 9

Do not dismiss anterior ST depression as merely reciprocal without obtaining posterior leads; it may represent a STEMI equivalent requiring immediate reperfusion. – ESC guideline 5
Do not postpone angiography in patients with refractory symptoms even if the initial troponin is negative; repeat troponin and ECG during pain episodes. – ESC guideline 9
Do not default to clopidogrel when ticagrelor or prasugrel are appropriate; the latter agents have superior outcomes in ACS. – ESC guideline 1

Continuous ECG monitoring for a minimum of 24 hours is recommended. – ESC guideline 10
A repeat 12‑lead ECG should be performed with any recurrent chest pain or clinical deterioration. – ESC guideline 6
Transthoracic echocardiography is advised to evaluate left‑ventricular function and to exclude mechanical complications. – ESC guideline 2
Serial troponin measurements are required when the initial result is non‑diagnostic. – ESC guideline 5