Which patients should undergo preoperative non-invasive investigations or coronary angiography?

Non-invasive testing refers to investigations other than angiography such as dipyridamole thallium scanning or dobutamine stress echocardiography. The literature on this question is overwhelming. It is best approached by nine simple steps. These are based on the recommendations of the joint consensus conference of the American College of Cardiology and the American Heart Association.1 Clinical predictors, functional capacity and magnitude of surgical risk can be assessed from Tables 101.3, 101.4 and 101.5 in the next question.

Step 1 What is the urgency of surgery?
If absolute emergency proceed to surgery, otherwise proceed to step 2.

Step 2 Has the patient undergone coronary revascularisation in the last five years?
If so and symptoms are stable, proceed to surgery. If not, or symptoms are unstable go to step 3.

Step 3 Has there been a coronary evaluation in the past two years?
If so and there are no changes or new symptoms proceed to surgery.
If not, or there have been changes go to step 4.

Step 4 Is there an unstable coronary syndrome or major clinical predictor of risk?
If so proceed direct to angiography. If not go to step 5.

Step 5 Are there intermediate clinical predictors of risk?
If so go to step 6. If not go to step 7.

Step 6 What is the functional capacity and magnitude of surgical risk?
If there are intermediate clinical predictors, then order noninvasive investigations if there is either poor function or high surgical risk. Otherwise go to surgery.

Step 7 Are there minor clinical predictors?
If so go to step 8. If not proceed to surgery.

Step 8 What is the functional capacity and magnitude of surgical risk?
If there are minor clinical predictors, then order non-invasive investigations if there are both poor function and high surgical risk.

Step 9
All patients have now been assigned to surgery, angiography or non-invasive testing. The results of non-invasive tests must incorporate both the absolute result (positive or negative) and quantification of the result (e.g. magnitude and regional location of ischaemic area). These results will determine which patients should proceed to angiography. Significant abnormalities require further assessment by angiography. Minor and intermediate abnormalities only require further assessment in the presence of low functional capacity or major surgical risk. It should be noted that, at least in high-risk patients undergoing vascular surgery, beta blockade is the only medical intervention proven to have major impact on outcome.