Preoperative Cardiovascular Evaluation for Noncardiac Surgery - An Update

1. Preoperative Cardiovascular Evaluation for Noncardiac Surgery - An Update February 27, 2002 Robert B. Preli

2. Overview • Scope of the Problem • Purpose of Clinical Practice Guidelines • ACC/AHA 2002 Guideline Update/Review • The ACP Guideline • Validation Study • Lee’s Revised Cardiac Risk Index • Conclusions

3. Scope of the Problem - Epidemiology • 27 million patients per year in the United States are given anesthesia for surgeries • 8 million have known CAD or risk factors • 50,000 who undergo noncardiac surgery will have a perioperative MI • 1 million will have a perioperative complication • Common reason for consultation during AIM rotation

4. Scope of the Problem:Purpose of Assessment • “Revascularization before noncardiac surgery to enable the patient to ‘get through’ the procedure is appropriate for only a small subset of patients.” • Determine who can go directly to surgery • Determine who: • have additional tests prior to surgery • needs medical management prior to surgery • Risk stratify patients, NOT “clear” them for surgery

5. Practice Guideline Characteristics • Comprehensive review of the evidence • Expert opinion used to make value judgements • Official endorsement by an organization • Intention to influence your practice patterns

6. ACC/AHA Guidelines • “Guidelines for Perioperative Cardiovascular Evaluation for Noncardiac Surgery” • First published in 1996 by the ACC/AHA • Updated in January, 2002 • Guidelines are available at: • www.acc.org • www.americanheart.org

7. Preop Cardiac Assessment

8. Exercise Tolerance

9. Surgical Risk

10. 2002 Guideline Highlights • New intermediate clinical predictor is “Renal Insufficiency” • Preoperative creatinine > 2.0 mg/dl • New “Shortcut to Noninvasive Testing” table to assist in clinical decision making • New “When and Which Test” table to assist in choosing testing modality • Strong endorsement for beta blocker use in the appropriate patient population • More than 400 new relevant articles went into the 2002 guidelines

12. Revascularization • In general, limit to patients who have a clearly defined need independent of surgery • Preoperative CABG • Should be reserved for high-risk patients undergoing high risk procedures in whom long-term outcome would be improved by CABG • Preoperative PCI • Indications are identical to the general ACC/AHA guidelines for the use of PTCA • Wait 2-4 weeks after stent placement for elective noncardiac surgery

13. Revascularization • Coronary Artery Surgery Study (CASS) • 24,959 patients in database from the NHLBI between 1974-1979 • All CASS patients had coronary angiography at enrollment • Database enrollees treated with CABG or medical management based on physician preference • Identified 3368 patients who required noncardiac surgery during 10 years of followup • Surgeries included general (631), orthopedic (214), urologic (327), minor (90) Eagle, Circulation, 1997;96

14. CASS • End points included mortality within 30 days of procedure or myocardial infarction • Among 1961 patients undergoing high risk surgery, prior CABG was associated with fewer events when compared to medical management: • Death: 1.7% versus 3.3% (p=0.03) • MI: 0.8% versus 2.7% (p=0.002) • 1297 patients undergoing low risk procedures had a mortality of <1% regardless of prior coronary treatment Eagle, Circulation, 1997;96

15. Medical Therapy - So What About Beta Blockers? • Mangano et al (NEJM, 1996) • Poldermans et al (NEJM, 1999)

16. Medical Therapy • Mangano et al (NEJM, 1996) • 200 men at a VA with CAD or at risk for CAD • Randomized to IV Atenolol 30 minutes prior to noncardiac surgery continued throughout hsopitalization versus placebo • No difference in perioperative mortality or cardiovascular endpoints • At 2 years: • Mortality ARR = 11%, NNT = 9 • CV events ARR = 15%, NNT= 7 • 2 year endpoints, aggressive HR control

17. Medical Therapy • Poldermans et al (NEJM, 1999) • 112 high-risk patients (positive DSE) • high-risk major vascular surgeries (AAA repair, Aorto-fem bypass) • Randomized to Bisoprolol 5-10 QD (starting one week prior to surgery and continued 30 days post-op), or standard care • Combined 30 day endpoints of mortality or non-fatal MI • ARR = 31%, NNT = 3 • Generalizability, aggressive HR control

18. So Who Gets Beta Blockers? Fleisher. NEJM, Vol 345, 2001

19. Medical Therapy - Summary • Very few randomized trials • Appropriately administered beta blockers may reduce the risk of MI and death in high-risk patients • If possible, start beta blockers days or weeks before elective surgery • Titrate dose to a resting HR between 50-60 • Alpha-2 agonists may have similar effects (clonidine, mivazerol)

22. ACP Guideline • Does not take into account a patient’s functional status • Does not tend to recommend stress testing in situations when patient is intermediate risk where ACC/AHA guideline is more test oriented

23. Mark Wilson’s Guideline • “If the patient walked into your clinic (and was not going to surgery), would you order a stress test based on their history and physical?” • “Let sleeping dogs lie.”

24. How Well Do We Risk Stratify? • “Prospective Evaluation of Cardiac Risk Indices for Patients Undergoing Noncardiac Surgery” Gilbert et al (Annals, 2000) • Compared four existing methods for predicting perioperative cardiac risk in a prospective cohort study • 2035 patients referred for medical consultation before urgent or elective non-cardiac surgery • Endpoints included cardiac events (MI, angina, or acute pulmonary edema), and death (all-cause mortality)

25. Gilbert - Methods • Patients were categorized according to the following indices: • American Society of Anesthesiologists (ASA), 1963 • Goldman, 1977 • Detsky (ACP algorithm), 1997 • Canadian Cardiovascular Society (CCS), 1976 • Cardiac events were defined clinically and according to generally accepted criteria • myocardial infarction, unstable angina, acute pulmonary edema • Death defined as all-cause mortality

26. Gilbert - Methods • To determine the accuracy of the stratification systems • Receiver-operating characteristic (ROC) curves were calculated for each index • Areas under the ROC curve (accuracy) were compared

27. Patient Characteristics (2035)

28. Gilbert - Results • Cardiac Events - 130 (6.4%) • MI - 36 (1.8%) • Pulmonary Edema - 67 (3.3%) • Unstable Angina - 27 (1.3%) • Deaths - 48 (2.4%)

29. Gilbert - ResultsAlgorithm Accuracy

30. Gilbert - Conclusions • None of the models was significantly superior to the others • Cardiac risk indices provide useful clinical information about risk, but have limited overall accuracy • There remains room for improvement in our ability to determine which patients are at greatest risk for cardiac complications

31. But Wait . . . • “Prediction of Perioperative Risk: The Glass May Be Three-Quarters Full”, Eagle et al (Annals, 2000) • Tested guidelines do not take into account functional status and therefore risk may have been underestimated • Patients may not have had implementation of medical therapy based on their risk • Most importantly, identification of risk is not synonymous with prediction of adverse events

32. Eagle - Editorial • The population studied was one in which there was a low prevalence of complications • Identification of high-risk individuals may have led to changes in therapy, and therefore low accuracy may be a marker of successful management

33. Lee’s Revised Cardiac Risk Index • Lee et al. “Derivation and Prospective Validation of a Simple Index for Prediction of Cardiac Risk of Major Noncardiac Surgery.” Circulation, 1999. • Prospective investigation to derive and validate a simple index for the prediction of the risk of cardiac complications in major elective noncardiac surgery

34. Lee - Methods • Patients > 50 years old • Nonemergent, noncardiac surgery • All patients had serial CK enzymes and EKG’s post-operatively • Major cardiac complications defined as MI, pulmonary edema, vfib, cardiac arrest, complete heart block

35. Lee - Subjects • Mean age = 66 +/- 10 years • 33% Orthopedic procedures • 40% High risk procedures • 16% History of MI

36. Lee - Subjects

37. Lee - Results • Patients who were using beta blockers at the time of admission had similar rates of complications as those who were not: • Beta blockers - 2.4% complications • No beta blockers - 1.8% complications

38. Lee - Results • 6 independent correlates of major cardiac complications were identified in the derivation cohort: • VariableComplication Rate • High risk surgery 3% • Ischemic heart disease 4% • Congestive heart failure 5% • Hx of CVA 6% • Insulin treated DM 6% • Serum creatinine > 2.0 mg/dl 9%

39. Lee - Results

40. Lee - Conclusions • “How the Revised Cardiac Risk Index should be used by clinicians remains to be defined” • Possibly perform noninvasive testing on classes III and IV

41. Conclusions • Purpose of preoperative assessment is NOT to “clear” the patient • Risk stratify with guidelines • Treat the patient • High risk patients may benefit from further testing • Remember beta blockers in the appropriate patient population