Acute Coronary Symptoms

Management

In acute coronary syndromes (ACS), the management strategy changes according to the patient’s diagnosis and the level of risk of death and future events. An overview of treatment options in ACS is shown in Figure 1.

ST-segment elevation myocardial infarction (STEMI)

Reperfusion is indicated in all patients with presumed STEMI (based on symptoms and ECG evidence) who present within 12 hours of symptom onset.¹ After 12 hours, reperfusion may still be considered; however, its benefits are less well-defined when there is no evidence of ongoing ischaemia.¹

On first medical contact, dyspnoea, pain and bradycardia should be treated with oxygen, opioids (IV) and atropine (IV), respectively. Reassurance of patients and significant others is important to reduce anxiety.¹ Ventricular fibrillation is a common cause of death in the hours following STEMI, and the availability of defibrillators is essential to improve survival.

Two main types of reperfusion therapy are recommended for patients with STEMI: primary PCI* and fibrinolysis. PCI is the preferred option when it can be performed within 2 hours of arrival at hospital; otherwise, the patient should receive fibrinolytic therapy unless there are contraindications to its use.¹

Chewable aspirin (150-325mg at once, followed by 75-160 mg/day for life) should be administered as soon as possible to all patients who have a working diagnosis of STEMI.¹ Clopidogrel (300-600 mg loading dose, followed by 75 mg/day) is also recommended for STEMI patients undergoing PCI or fibrinolysis. It is not known whether the glycoprotein IIb/IIIa inhibitor abciximab offers additional benefits in patients undergoing PCI who have already received clopidogrel,although antithrombotic therapy (e.g. with unfractionated heparin or bivalirudin) is recommended in these patients.

Coronary artery bypass grafting (CABG) has a limited role in the acute treatment of STEMI, but may be indicated (for example) when PCI fails or when the occlusion is not amenable to PCI.¹

Implantable cardioverter-defibrillators (ICDs) are indicated to reduce mortality in patients with left ventricular dysfunction (see section 5.4).¹

*’Primary PCI’ is defined as angioplasty and/or stenting without prior or concomitant fibrinolytic therapy.¹

Non-ST-segment elevation acute coronary syndromes (NSTE-ACS)

Oxygen, atropine and opioid analgesia may be required at first medical contact in patients with NSTE-ACS, as for patients with STEMI.³

In the initial pharmacological treatment of NSTE-ACS, beta-blockers and nitrates are recommended to reduce myocardial workload and oxygen consumption; calcium antagonists may be used when beta-blockers are contraindicated.² Antithrombotic therapy (e.g. unfractionated or low molecular weight heparin; fondaparinux) is recommended, but the exact choice of drug and regimen depends on the management strategy that is to be followed (see below). Antiplatelet therapy, with aspirin and clopidogrel (at the same doses as used in STEMI, see above), is recommended for all patients unless contraindicated.

Decisions on the use of invasive strategies in patients with NSTE-ACS are guided by level of risk, which is assessed using validated tools such as the GRACE and TIMI risk scores.² Criteria such as age, systolic BP, heart rate, Killip class and presence/absence of diabetes are used to calculate the risk score, which is then converted into a risk category (low, intermediate or high).² Depending on the level of risk, an urgent invasive, early invasive or conservative management strategy may be adopted.²

Urgent coronary angiography is recommended in patients with persistent angina, ECG changes, haemodynamic instability or life-threatening arrhythmias. When risk is intermediate or high, but there are no life-threatening features,early angiography (within 72 hours) is recommended. Low-risk patients are managed conservatively (i.e. non-invasively).

Fibrinolytic therapy is not indicated in NSTE-ACS because of an unfavourable risk-benefit ratio.³

Figure 1. Simplified algorithm showing main treatment strategies and decision points in the management of ACS.^1-3