I fully agree with Dr. Topf that clinical skills are fundamental to deciding when to do noncardiac surgery in patients with several illnesses. The issue of perioperative ischemia and its significance is more complex. The paradigm I propose is to divide patients having noncardiac surgery into two groups. The first group includes patients with angina on minimal exertion or a syndrome suggesting ruptured coronary plaque. In the former, myocardial blood flow, although sufficient at rest or with minimal exertion, cannot increase adequately during the added stress of noncardiac surgery. In the latter case, the added stress can cause further damage to the plaque and secondary thrombus formation. In both situations, the risk for perioperative ischemia and infarction is high; aggressive, generally invasive cardiac evaluation before noncardiac surgery is appropriate [1]. The second group comprises patients with an old myocardial infarction, stable angina, or occult disease. In my opinion, the development of perioperative ischemia as reflected by ST-T changes represents a positive stress test result. In this case, the noncardiac surgery is the stress. To avoid prolonged ischemia, which can lead to infarction, postoperative stress and pain must be aggressively managed. This is analogous to stopping the conventional exercise or pharmacologic test when ischemia occurs. If, however, the patient remains tachycardic after surgery, the ischemia may result in infarction.

Dr. Topf's last point raises an even more complex problem. Fleisher and Eagle [1] suggest using the preoperative evaluation as an opportunity to optimize management of manifest disease and to detect occult disease. This assumes not only that noninvasive testing can be used to select the patient who will benefit from prophylactic revascularization before noncardiac surgery but also that noninvasive risk stratification is a useful strategy for patients with coronary artery disease. However, numerous studies have shown consistently poor positive predictive values for noninvasive testing [2, 3].

Thus, until we have tests with higher positive predictive values or therapy associated with low mortality and morbidity, preoperative evaluation should remain focused on the question, Can this patient with this clinical picture have noncardiac surgery?