The patient then underwent a stress tetrofosmin scan within 24 hours of presentation (exercise or pharmacological stress for those who cannot exercise). Tetrofosmin scans was be done at NHC or the Department of Nuclear Medicine, SGH. Patients were monitored until the test was completed. If the stress tetrofosmin scan turned out to be positive, the patient was then admitted to the hospital for further management. If the stress tetrofosmin scan was negative, the patient was released from ED with instructions for follow-up in the cardiology clinic as an outpatient.