Mapping out next steps based on risk score
The next step in the preoperative evaluation process is to calculate your patient’s risk score and determine whether it is low or high. If the risk is determined to be low—either an RCRI score <2 or an ACS NSQIP cardiac complication risk <1%—the patient can be referred to surgery without further evaluation.2
If the calculator suggests higher risk, the patient’s functional status should be assessed. If the patient has a functional status of >4 metabolic equivalents (METs), then the patient can be recommended for surgery without further evaluation.2 Examples of activities that are greater than 4 METs are yard work such as raking leaves, weeding, or pushing a power mower; sexual relations; climbing a flight of stairs; walking up a hill; and participating in moderate recreational activities like golf, bowling, dancing, doubles tennis, or throwing a baseball or football.9
Patient can’t perform >4 METs? If the patient does not have a functional capacity of >4 METs, further risk stratification should be considered if the results would change management.2 Prior guidelines recommended either perioperative beta-blockers to mitigate risk or coronary interventions, but both are controversial due to lack of proven benefit.
Perioperative beta-blocker use. A recommendation to consider starting beta-blockers at least one day prior to surgery remains in the 2014 ACC/AHA guidelines for patients with 3 or more RCRI risk factors.2 But a group of studies supporting beta-blocker use has been discredited due to serious flaws and fabricated data. At the same time, a large study arguing against perioperative beta-blockers has been criticized for starting high doses of beta-blockers on the day of surgery.2,10,11 In the end, mortality benefit from perioperative beta-blockers is uncertain, and the suggested reduction in cardiac events is partially offset by an increased risk of stroke.2
Stress testing is of questionable value. A patient with high cardiac risk (as evaluated with a calculator) may need to forego the surgical procedure or undergo a modified procedure. Alternatively, he or she may need to be referred to a cardiologist for consultation and possible pharmacologic nuclear stress testing. Although a normal stress test has a high negative predictive value, an abnormal test often leads to percutaneous coronary intervention or bypass surgery, and neither has been shown to reduce cardiac surgical risk.2 Percutaneous coronary interventions require a period of dual antiplatelet therapy, delaying surgery for unproven benefit.2
EKGs and echocardiograms are of limited use. An anesthesia group or surgical center will often require an electrocardiogram (EKG) as part of a preoperative evaluation, but preoperative evaluation by EKG or echocardiogram is controversial due to unproven benefits and potential risks. The 2014 ACC/AHA guidelines recommend against a 12-lead EKG for patients with low cardiac risk using the RCRI or ACS NSQIP or those who are having a low-risk procedure, such as endoscopy or cataract surgery.2 The United States Preventive Health Services Task Force also recommends against screening low-risk patients and says that screening EKGs and stress testing in asymptomatic medium- to high-risk patients is of undetermined value.12 They noted no evidence of benefit from resting or exercise EKG, with harm from a 1.7% complication rate of angiography, which is performed after up to 2.9% of exercise EKG testing.12
There are no recommendations for preoperative echocardiogram in the asymptomatic patient. Only unexplained dyspnea or other clinical signs of heart failure require an echocardiogram. For patients with known heart failure that is clinically stable, the ACC/AHA guidelines suggest that an echocardiogram should be performed within the year prior to surgery, although this is based on expert opinion.2
Because of the controversy over both coronary interventions and perioperative beta-blocker therapy, consider cardiology referral for a patient with poor functional activity level who does not meet low-risk criteria. While stress testing is acceptable, it may not lead to improved patient outcomes.