THE CONTEXT
The passage describes ECG criteria, timing and outcomes of reperfusion, and distinguishes immediate treatment from inpatient intervention in non-ST elevation presentations.
Immediate PCI: indications and timing
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Immediate reperfusion with PCI is indicated for new bundle branch block or characteristic ST elevation in two contiguous leads: at least 1 mm in limb leads or at least 2 mm in chest leads.
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PCI is the treatment of choice for patients presenting within 12 hours of symptom onset.
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If PCI cannot be performed within 120 minutes and thrombolysis is contraindicated, PCI should be performed as soon as practically possible.
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PCI should be considered within the first 24 hours even after spontaneous reperfusion or successful thrombolytic treatment.
Effects of PCI
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Coronary artery patency is restored in over 95% of patients undergoing PCI.
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PCI preserves left ventricular function, markedly reduces progression to heart failure and more than halves recurrent myocardial infarction rates.
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Clinical trials report more than 95% survival at 1 year. Successful reperfusion is associated with rapid pain relief, resolution of acute ST elevation and occasional transient arrhythmias.
Non-ST elevation acute coronary syndrome
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The source states that reperfusion with PCI provides no mortality benefit in non-ST elevation acute coronary syndrome but can reduce rehospitalisation with recurrent non-fatal myocardial infarction.
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These benefits are more limited in patients older than 75 years.
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Selected medium- to high-risk patients benefit from inpatient coronary angiography and revascularisation. Intervention need not occur within the first 12 hours unless high-risk features, such as ongoing chest pain or ECG changes, are present.
When timely primary PCI is unavailable
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Patients with ST elevation myocardial infarction should receive thrombolysis if primary PCI cannot be achieved promptly.
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Thrombolysis provides less survival advantage than primary PCI, but its mortality reduction is maintained for at least 10 years.