• Risk stratification before hospital discharge is an important aspect of manage-ment and determines whether coronary angiography is indicated. • The first step is to determine whether the clinical variables indicatine a relatively high risk for future cardiac events are present:
1. Patients who have recurrent ischaemia at rest or with mild activity, who have had evidence of congestive heart failure or who are known to have an ejection traction below 40% and in whom there are no contraindications for revas-cularization should undergo cardiac catheterization and coronary angiography. Revascularization should then be carried out if the coronary anatomy is suitable and there are no contraindications.
2. Patients who have had an episode of ventricular fibrillation or sustained ven-tricular tachycardia more than 48 hours after acute MI should be considered for electrophysiological study or amiodarone therapy, or both.
3. In patients with non-ST segment elevation M1 or unstable angina who appear on clinical grounds to be candidates for coronary revascularization, coronary vascularization should be performed. Revascularization may then be carried out if the coronary anatomy is appropriate.
• Patients without these clinical indicators of high risk should undergo an assess-ment of left ventricular function (echocardiogram or radionuclide angiogram and submaximal stress) before hospital discharge. If the test is negative the patient may return for a symptom-limited exercise test at 3-6 weeks. If that too is negative he or she can remain on medical therapy and risk factor reduction. If the resting ejection fraction is <40 data-blogger-escaped-abnormal="" data-blogger-escaped-if="" data-blogger-escaped-is="" data-blogger-escaped-markedly="" data-blogger-escaped-or="" data-blogger-escaped-stress="" data-blogger-escaped-the="">2 nlm ST segment depression, hypotension at peak exercise or low working capacity) then coronary angiography should be carried out if there are no contraindications to revascularization. • In patients in whom the ECG is not intepretable because of resting ST-T wave abnormalities, digitalis therapy or left bundle branch block, rest and exercise radionuclide myocardial perfusion scintigraphy (with thallium or sestamibi) or rest and exercise echocardiography should be performed. Patients who cannot exercise should undergo a pharmacologic stress imaging study such as adenosine or dipyridamole myocardial perfusion scintigraphy or echocardiography with dobutamine or dipyridamole stress. A marked abnormality in any of these tests or a resting ejection fraction below 40%, measured by echocardiography or a radionuclide technique, should be followed by coronary angiography.