Fundamentals of Preoperative Evaluation

Educational Objectives

The goal of this program is to improve preoperative cardiac evaluation for noncardiac surgery. After hearing and assimilating this program, the clinician will be better able to:

1. List strong risk factors for cardiac complications.
2. Use a validated tool to assess perioperative cardiac risk.
3. Identify patients who would benefit from preoperative cardiac testing.
4. Explain evidence assessing the use of aspirin in patients at risk for cardiac complications.
5. Compare use of atorvastatin vs placebo in patients at risk for cardiovascular complications.

Summary

Clinical risk assessment: includes information from the patient’s history, physical examination, and medical chart; a history of coronary artery disease (CAD) and limited functional capacity and exercise tolerance are considered to be strong risk predictors, while hypertension, high cholesterol, and smoking are relatively weak predictors; documented end-organ disease indicates a higher risk for cardiac complications; the goals of preoperative assessment are to identify patients at increased risk for complications and to prevent delays in surgery for those at lower risk; ordering unnecessary tests or procedures can delay surgery and lead to complications; end-organ disease (eg, CAD, congestive heart failure [CHF]), and their equivalents (eg, diabetes mellitus [DM] treated with insulin, vascular diseases [stroke, transient ischemic attack [TIA]), are associated with an increased risk for cardiac complications; poor functional status is defined as a cutoff of 4 metabolic equivalents (METS; eg, walking 2 blocks at a normal pace, climbing 2 flights of stairs); poor functional capacity is associated with a higher risk to the same degree as some end organ disease, even in the absence of CVD; hence, it is critical to consider both patient-specific risk and surgical risk

Procedural risk factors: patients with CAD can undergo minor procedures with minimal risk; patients undergoing surgeries that stress the cardiovascular system may be at risk, even in the absence of heart disease; high-risk surgery is defined as having a ≥5% chance of a major adverse cardiac event (MACE; eg, major aortic operations, emergency major surgeries, or procedures with significant fluid shifts or blood loss [eg, Whipple procedure, organ transplantation]); most surgeries for which hospitalists perform preoperative assessments are of intermediate risk (eg, carotid endarterectomy, major abdominal or thoracic procedures, head and neck cancer surgeries); elective orthopedic surgeries are usually at the lower end of the intermediate risk; low-risk procedures often do not require hospitalization (eg, endoscopies, minimal laparoscopic procedures); usually, no further evaluation is necessary before low-risk surgeries if the patient has no active cardiac issues

Revised cardiac risk index (RCRI): is the most commonly used preoperative cardiac risk prediction tool; it includes factors such as ischemic CVD, CHF, insulin-dependent DM, elevated creatinine (>2 mg/dL), a history of stroke or TIA, and the type of surgery; high-risk surgeries are defined as intraperitoneal, intrathoracic, or vascular procedures above the inguinal ligament; the risk is determined by combining the scores, which range from 0 to 6; complications, as defined by the speaker, include myocardial infarction (MI) and cardiac arrest (CA); an RCRI score of 0 or 1 is considered a normal risk, while a score ≥2 is considered elevated risk; these thresholds are lower than those seen with some other risk calculators, which include additional factors (eg, pulmonary edema); the RCRI considers only hard endpoints (eg, MI, CA)

The National Surgical Quality Improvement Program (NSQIP): is a widely used risk prediction tool that defines complications as the 30-day incidence of MI and CA; the 5 variables included are the type of surgery, patient age, serum creatinine (>1.5 mg/dL is the cutoff), functional status (independent, partially, or fully dependent with ADLs), and the American Society of Anesthesiologists (ASA) classification; the ASA classification is a gestalt identification based on the patient’s health status; ASA class 1 indicates a healthy, normal patient, 2 denotes mild systemic disease, 3 indicates severe systemic disease, 4 refers to severe systemic disease that poses a constant threat to life, and class 5 is when the patient is moribund (not expected to survive without surgery); the QXMD calculator provides a tool for this scoring system; the NSQIP tool has a good performance, with area under the curve of 0.88; it includes only 5 variables and does not account for all available information; a score of 0% to 1% score indicates average risk and >1% indicates elevated risk

RCRI vs NSQIP: the guidelines from the American College of Cardiology (ACC) and the American Heart Association (AHA) recommend using a validated risk prediction tool when assessing a patient with known cardiovascular disease for noncardiac surgery but do not endorse a specific tool; they acknowledge that both the RCRI and NSQIP (GUPTA tool) are widely used; the speaker prefers NSQIP over RCRI, believing it to be more contemporary and better externally validated; the NSQIP was developed from a larger dataset from >200 hospitals from 2007 to 2008, whereas RCRI was developed using a smaller data set from a single hospital between 1989 and 1994; the RCRI includes silent ischemic events detected using creatinine kinase-MB and serial electrocardiography, while NSQIP relies on clinical reports of MI; the revised risk in RCRI has increased over time, while NSQIP provides a more realistic estimate in the speaker’s opinion; there are certain conditions listed by ACC and AHA, including unstable coronary syndromes, decompensated heart failure (HF), significant symptomatic arrhythmias, and severe valve disease, particularly critical aortic stenosis, that need further evaluation; if a patient with any of these conditions visits a primary care physician or is in need of surgery, delay surgery and refer the patient for a cardiology evaluation

Biomarkers: N-terminal pro-B-type natriuretic peptide (NT-proBNP) or BNP can predict various cardiovascular complications and outpatient long-term survival issues and also risk after noncardiac surgery; a meta-analysis by Rodseth et al (2013) found that patients with BNP >92 pg/mL and pro-BNP >300 pg/mL had a 30-day incidence of death or MI after surgery of 21% compared with 5% in those who had biomarker levels below the cutoff; based on the above study, American, Canadian, and European guidelines suggest that BNP or proBNP testing is reasonable for high-risk patients to supplement clinical evaluation; order tests only if the results will affect the management plan, not routinely; while biomarker levels below the cutoff indicate low risk; elevated levels indicate high risk but do not necessarily predict poor outcomes

Noninvasive stress testing: becomes increasingly less important overall with each new iteration of the guidelines; stress testing as a preoperative evaluation tool has primarily been studied in patients undergoing vascular surgery, where it has a strong negative predictive value; however, it has a weak positive predictive value, as an abnormal result does not significantly alter decision-making unless the pretest risk is high; therefore, the preoperative guidelines de-emphasize the use of stress testing as an additional risk stratification test; the goal of a stress test or coronary computed tomography angiography (CCTA) is not to diagnose CAD or ischemic potential but to identify severe CAD (left main disease or triple vessel disease with reduced ejection fraction) that would be an indication for revascularization (eg, stenting, coronary artery bypass surgery [CABG]) even without impending surgery; an abnormal CCTA also has low positive predictive value but can be considered in patients who have a high risk on a validated risk prediction tool

Echocardiography: is fast and relatively easy; the guidelines recommend its use to evaluate left ventricular function in patients with unexplained symptoms or signs (eg, leg edema, shortness of breath) suggesting HF or worsening symptoms in patients with a known history of HF; do not routinely assess left ventricular function in asymptomatic and clinically stable patients, even if they have HF; it is also recommended to assess valvular function in patients with known or suspected moderate to severe stenotic or regurgitant heart disease to check whether their condition has worsened or if the last echocardiography is >1 yr ago

Stepwise approach to preoperative cardiac assessment: the guidelines do not replace clinical judgment; they represent expert consensus; the first step is to use a validated cardiac risk prediction tool; a low-risk score indicates that no further evaluation is required to proceed with surgery; however, guidelines recommend additional testing even with low-risk scores in patients with severe valve disease, severe pulmonary hypertension, high-risk congenital heart disease, those with prior CABG or stents on antiplatelet medications, cardiac implanted electronic devices or pacemakers, recent strokes, or extreme frailty; for many patients, the evaluation ends at step 1; if the patient’s risk score is high, assess functional capacity (step 2); if the patient has acceptable functional capacity, proceed with surgery; the ability to function at ≥4 METS is generally considered acceptable; the Duke Activity Status Index (DASI) is slightly more accurate; DASI is a questionnaire; a score ≥34 is considered acceptable functional capacity; if the patient has poor functional capacity, assess risk using BNP or NT-proBNP biomarkers (step 3); patients with low levels (eg, <92 pg/mL of BNP and <300 pg/mL of NT-proBNP) do not need further evaluation; if all 3 steps fail, further diagnostic testing (step 4) is an individualized, patient-specific decision, but only if the results will affect the management; a multidisciplinary discussion with surgeons, cardiologists, and anesthesiologists to weigh the risks and benefits of further testing is optimal; the patient can proceed with surgery if the test results are reassuring; if the tests show high-risk features, surgery may be delayed or canceled, and alternative options (eg, palliation, less or noninvasive procedures) may need to be explored

Risk Reduction

Coronary revascularization: McFalls et al (2004) studied 510 patients undergoing vascular surgery, all of whom had 70% occlusion in ≥1 vessel; patients with severe CAD were excluded; those in the interventional group received revascularization plus medical management vs medical management alone; 1.7% of patients in the intervention group died because of its complications, while 6% suffered an MI; there was no significant difference in 30 days, postoperative, or long-term mortality; based on these findings, guideline indications to revascularize a patient prior to surgery are the same as for a patient not undergoing surgery

After revascularization: if revascularization is performed prior to surgery, it can delay the surgery because of the need to hold antiplatelet therapy; therefore, the guidelines recommend a 12-mo holding period for a drug-eluting stent placed for acute CAD, a 6-mo holding period for stable CAD, and a 3-mo holding period for time-sensitive surgeries; for a bare metal stent placed in a patient, they recommend a 30-day waiting period

Medical management: historically, β-blockers were frequently used to reduce postoperative MI and mortality, as early studies suggested a reduction in complications, but subsequent larger studies failed to replicate these findings; the POISE study group trial (2008) found that β-blockers slightly reduced the incidence of MI but increased the rates of stroke and overall mortality; therefore, current guidelines recommend continuing a β-blocker if the patient is already on it, particularly if the BP is under control; however, only start a β-blocker if there is a new indication or an independent reason to start it; it is recommended to start ≈7 days before surgery to assess the tolerability and adjust the dose; if surgery cannot be delayed for 7 days, proceed and do not start a β-blocker; a β-blocker on the day of surgery is not recommended

Aspirin: POISE-2 trial (Devereaux et al [2014]) randomized patients at risk for cardiac complications, including those with heart disease or multiple cardiac RFs, to receive aspirin or a placebo at time of surgery; death or MI did not differ between the groups; however, major bleeding occurred slightly more often in the aspirin group; a subsequent post hoc analysis focused on patients with a prior stent and found that aspirin was more effective at reducing death or MI compared with placebo; based on this reanalysis, the guidelines concluded that patients with CAD without a prior stent may continue taking aspirin if there are no severe bleeding concerns, but this is not a strong recommendation; a grade I recommendation states that aspirin should be continued before elective noncardiac surgery in patients with CAD who have a prior stent to reduce the risk for cardiac complications; aspirin should not be started in patients who are not already taking it

Statins: there is mixed evidence regarding statin use in patients undergoing noncardiac surgery; several observational studies and small randomized trials suggest that statins can reduce cardiac complications in these patients, but the timing for initiating statins remains unclear; LOAD trial (Berwanger et al [2016]) found no difference in death, nonfatal MI, or stroke among statin-naïve patients at risk for cardiovascular complications who received atorvastatin (Lipitor) ≤18 hr before major surgery compared with placebo; other trials indicate that statins are beneficial when started several weeks or months in advance of elective surgery; the guidelines recommend continuing statins for patients undergoing noncardiac surgery who are already on them; guidelines also recommend the perioperative initiation of statins in statin-naïve adults who meet the criteria for statins and are scheduled for noncardiac surgery with the intention for long-term use

Readings

Balfour PC Jr, Gonzalez JA, Kramer CM. Non-invasive assessment of low- and intermediate-risk patients with chest pain. Trends Cardiovasc Med. 2017;27(3):182-189. doi:10.1016/j.tcm.2016.08.006; Berwanger O, de Barros E Silva PG, Barbosa RR, et al. Atorvastatin for high-risk statin-naïve patients undergoing noncardiac surgery: the Lowering the Risk of Operative Complications Using Atorvastatin Loading Dose (LOAD) randomized trial. Am Heart J. 2017;184:88-96. doi:10.1016/j.ahj.2016.11.001; Bronheim RS, Oermann EK, Bronheim DS, et al. Revised cardiac risk index as a predictor for myocardial infarction and cardiac arrest following posterior lumbar decompression. Spine (Phila Pa 1976). 2019;44(3):E187-E193. doi:10.1097/BRS.0000000000002783; Devereaux PJ, Mrkobrada M, Sessler DI, et al. Aspirin in patients undergoing noncardiac surgery. N Engl J Med. 2014;370(16):1494-1503. doi:10.1056/NEJMoa1401105; Helft G. Dual antiplatelet therapy duration after drug-eluting stents: how long?. J Thorac Dis. 2016;8(8):E844-E846. doi:10.21037/jtd.2016.07.45; McFalls EO, Ward HB, Moritz TE, et al. Coronary-artery revascularization before elective major vascular surgery. N Engl J Med. 2004;351(27):2795-2804. doi:10.1056/NEJMoa041905; Moraes CMT, Corrêa LM, Procópio RJ, et al. Tools and scores for general and cardiovascular perioperative risk assessment: a narrative review. Rev Col Bras Cir. 2022;49:e20223124. doi:10.1590/0100-6991e-20223124; Plümer L, Seiffert M, Punke MA, et al. Aspirin before elective surgery-stop or continue?. Dtsch Arztebl Int. 2017;114(27-28):473-480. doi:10.3238/arztebl.2017.0473; POISE Study Group, Devereaux PJ, Yang H, et al. Effects of extended-release metoprolol succinate in patients undergoing non-cardiac surgery (POISE trial): a randomised controlled trial. Lancet. 2008;371(9627):1839-1847. doi:10.1016/S0140-6736(08)60601-7; Rodseth RN, Biccard BM, Chu R, et al. Postoperative B-type natriuretic peptide for prediction of major cardiac events in patients undergoing noncardiac surgery: systematic review and individual patient meta-analysis. Anesthesiology. 2013;119(2):270-283. doi:10.1097/ALN.0b013e31829083f1; Shim CY. Preoperative cardiac evaluation with transthoracic echocardiography before non-cardiac surgery. Korean J Anesthesiol. 2017;70(4):390-397. doi:10.4097/kjae.2017.70.4.390; Silvapulle E, Darvall J. Subjective methods for preoperative assessment of functional capacity. BJA Educ. 2022;22(7):249-257. doi:10.1016/j.bjae.2022.02.007; Thompson A, Fleischmann KE, Smilowitz NR, et al. 2024 AHA/ACC/ACS/ASNC/HRS/SCA/SCCT/SCMR/SVM Guideline for Perioperative Cardiovascular Management for Noncardiac Surgery: a report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines [published correction appears in Circulation. 2024;150(21):e466. doi: 10.1161/CIR.0000000000001298]. Circulation. 2024;150(19):e351-e442. doi:10.1161/CIR.0000000000001285; van Bussel EF, Hoevenaar-Blom MP, Poortvliet RKE, et al. Predictive value of traditional risk factors for cardiovascular disease in older people: a systematic review. Prev Med. 2020;132:105986. doi:10.1016/j.ypmed.2020.105986.

Disclosures

For this program, members of the faculty and planning committee reported nothing relevant to disclose.

Acknowledgements

Dr. Cheng was recorded at the 28th Annual Management of the Hospitalized Patient, held October 17-19, 2024, in San Francisco, CA, and presented by the University of California, San Francisco, School of Medicine. For information about upcoming CME activities from this presenter, please visit cme.ucsf.edu. Audio Digest thanks Dr. Cheng and the University of California, San Francisco, School of Medicine for their cooperation in the production of this program.

CME/CE INFO

Accreditation:

The Audio- Digest Foundation is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

The Audio- Digest Foundation designates this enduring material for a maximum of 2.00 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Audio Digest Foundation is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center's (ANCC's) Commission on Accreditation. Audio Digest Foundation designates this activity for 2.00 CE contact hours.

Lecture ID:

AN670701

Expiration:

This CME course qualifies for AMA PRA Category 1 Credits™ for 3 years from the date of publication.

Instructions:

To earn CME/CE credit for this course, you must complete all the following components in the order recommended: (1) Review introductory course content, including Educational Objectives and Faculty/Planner Disclosures; (2) Listen to the audio program and review accompanying learning materials; (3) Complete posttest (only after completing Step 2) and earn a passing score of at least 80%. Taking the course Pretest and completing the Evaluation Survey are strongly recommended (but not mandatory) components of completing this CME/CE course.

Estimated time to complete this CME/CE course:

Approximately 2x the length of the recorded lecture to account for time spent studying accompanying learning materials and completing tests.