Physician estimates of perioperative cardiac risk in patients undergoing noncardiac surgery

Background: We know little about how physicians assess perioperative cardiac risk in patients undergoing noncardiac surgery. Objectives: To evaluate preoperative medical consultations and determine the extent to which consultants used validated cardiac risk indices and specialized noninvasive cardiac tests, and to assess agreement between physician ratings of cardiac risk (low, moderate, or high) and risk estimates derived using validated cardiac risk indices or, in the case of vascular surgery, a risk index. Methods: This observational study was conducted at 5 Canadian teaching hospitals affiliated with 2 universities. We retrospectively evaluated 308 preoperative consultations performed in 297 patients and examined the frequency with which consultants recorded the use of validated cardiac risk indices. We used kappa statistics to quantify the extent to which physician ratings of cardiac risk agreed with risk estimates derived using validated cardiac risk indices. Results: Physicians recorded use of a risk index in 31% of the consultations, but the index used was almost always the suboptimal classification of the American Society of Anesthesiologists. The agreement between physician estimates of cardiac risk and the validated cardiac risk indices was only fair, with a weighted kappa of 0.38 (95% confidence interval, 0.28-0.49). Overestimation and underestimation of cardiac risk occurred in 16% and 13% of the consultations, respectively. Consultants did not order dipyridamole thallium imaging or dobutamine stress echocardiography for any moderate-risk patients undergoing vascular surgery. Conclusions: Physicians underuse validated cardiac risk indices, and the agreement between the cardiac risk estimates and risk as determined by validated cardiac indices is suboptimal. Physicians are also underusing dipyridamole thallium imaging and dobutamine stress echocardiography for moderate-risk patients undergoing vascular surgery.