The role of scintigraphic perfusion imaging for predicting ischemic cardiac events in noncardiac surgery.

The prediction of perioperative cardiac events remains a challenging issue in clinical cardiology. The most important cause of perioperative cardiac morbidity and death continues to be myocardial infarction, which is associated with a high prevalence of occult coronary artery disease. A large amount of data substantiates the validity of scintigraphic perfusion imaging for accurate diagnosis of coronary artery disease, as well as the prediction of prognosis in stable coronary disease, post-myocardial infarction, and in the preoperative setting. A normal stress perfusion scan predicts an extremely low rate of future cardiac events. The best predictor of future adverse cardiac events is the quantitative extent, severity, and reversibility of jeopardized myocardium, parameters that are easily assessed with perfusion scintigraphy. Although the sensitivity of scintigraphy for detecting coronary disease is high, the reported specificity of abnormal perfusion scans for predicting cardiac events is variable. Indiscriminant use of this technique with subsequent referral for angiography based on the presence of any perfusion abnormality will result in excessive, costly, and potentially dangerous screening procedures. However, thoughtful consideration of both the extent and severity of perfusion abnormality can appropriately stratify the majority of patients into low-, intermediate-, and high-risk groups. Further efforts should be directed at prospectively evaluating the use of quantitative perfusion defect and reversibility scores in various subgroups of patients to optimize the specificity of these techniques and determine the optimal degree of defect extent and severity that warrants invasive evaluation.