Myocardial Scan

Indications:

1. Detection and evaluation of known or suspected coronary artery disease.

2. Follow up of medical or surgical therapy of coronary artery disease.

Principle:

• Myocardial agents such as Sestamibi and Tetrafosmin are markers for viable, perfused myocardiam. A perfusion abnormality on an exercise scan that returns to normal on a repeat rest study indicates reversible myocardial ischaemia.

Preparation and Procedure:

• The patient should fast at least 3 hours prior to the study. They should not have any food or drinks containing caffeine for 24 hours before the study, or during the day of study.

• The patient should withdraw from beta-blockers for 48 hours (from the day before the stress study, continuing until the end of the study).

• Nitrates and calcium channel blockers must be stopped for 24 hours before the study.

• Myocardial Rest and Stress studies take approx. 2 hours each. They may be performed on the same day or on separate days. Stress can be achieved by exersize, persantin, Dobutamine, Adenosine or a combination of exercise and pharmacological stress.

Comments:

Myocardial Perfusion Scans (MPS) are useful in assessing the extent and severity of myocardial ischaemia. It is critical to correlate the results of ECG testing and clinical data with scan results. MPS aid in pre-operative evaluation by helping to determine the amount of scar versus ischaemia present. The scan is often used to assess the significance of an equivocal stenosis seen on angiogram and to triage patients into medical or surgical management programs. The MPS also provide valuable data on LV size, volume and LVEF. The greatest strength of MPS are their prognostic value. A negative MPS predicts a low risk and low annualised cardiac event rate of 0.6% per year for 3 years.

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