First Canadian guideline on perioperative cardiac risk assessment and management for patients undergoing non-cardiac surgery

By Dr. Terence Yung (biography, no disclosures) and Dr. Erin Morley (biography, no disclosures)

What we have noticed in the management of perioperative patients

Physicians who see patients for preoperative assessment often face the dilemma of accurately determining a patients’ cardiac risk. Patients may have limited mobility and thus do not necessarily elicit cardiac symptoms even if there is significant flow-limiting coronary artery disease. To reassure the patient and inform the physician and surgeon, pharmacological stress tests are often ordered to further risk stratify these patients. Indeed, this practice is supported by the American Heart Association (AHA) guideline on this topic, which makes a Class IIa recommendation on preoperative pharmacological stress testing for those who are at elevated risk with unknown functional capacity if it would change management¹. Positive findings on a stress test can lead to invasive cardiac angiogram; this may prompt angioplasty and stent implantation, which leads to dual antiplatelet therapy for up to one years’ time.

This cascade of events initiated by a positive stress test may not necessarily be the best for patients. In the case of elective surgeries, the delay in surgery up to one year could significantly impact quality of life. For semi-urgent surgeries, such as those for malignancy, the delay to get medical clearance from a specialist, and the additional uncertainty of a mild to moderately positive stress test only adds to the stress already faced by a patient with a cancer diagnosis. Ultimately if these patients finally undergo surgeries without major complications, one must wonder whether the seemingly harmless stress tests ordered preoperatively are truly benign at all. The first Canadian Cardiovascular Society (CCS) guideline on perioperative cardiac risk assessment and management has been published in October 2016, and it takes a slightly different stance on many of these topics compared to the AHA guideline² (View with CPSBC or UBC).

Data that answers these questions

In contrast to the AHA guideline, the Canadian guideline makes a strong recommendation against performing pharmacological stress testing preoperatively for enhancing perioperative cardiovascular risk estimation (Strong Recommendation, Low-Quality Evidence). Since the 2014 AHA guideline was published, there have been no major publications in this area to shed any new insight as to the value of pharmacological stress testing. In other words, both the AHA and CCS guideline committees on this topic made recommendations using the same existing literature. How then, did the expert panel for AHA and CCS arrive at different conclusions?

The CCS guideline panel graded the quality of the existing literature on preoperative pharmacological stress testing and found serious limitations in many studies’ methodology. Most of these studies had relatively small sample sizes with very small number of events and no systematic outcome monitoring, which lead to potential selection biases that may contribute to inaccurate risk prediction^2,3. These studies did not evaluate whether there was any incremental value of these stress tests to clinical risk scores such as the Revised Cardiac Risk Index (RCRI). Moreover, the CCS expert panel places more value and preference on preoperative BNP/ NT-proBNP testing, not only due to its higher quality of evidence, but also due to the lower cost and rapidity of results. For these reasons, this led to the strong recommendation against preoperative pharmacological stress testing to enhance cardiac risk prediction in the asymptomatic individual.

Compared to the AHA guideline, the CCS guideline makes a strong recommendation on preoperative NT-proBNP or BNP to enhance perioperative cardiac risk estimation in patients who are at increased risk (Moderate-Quality Evidence). This is largely based on a high quality individual patient data meta-analysis that included 2179 patients by Rodseth et al., that found improved risk prediction compared to clinical risk indices alone⁴. BNP/ NT-proBNP testing could accurately identify and reclassify both high and low risk patients into appropriate risk categories. NT-proBNP less than 300ng/L or BNP less than 92mg/L can safely classify patients into a low postoperative risk category.

The CCS also recommends risk stratification using the RCRI. One point is given for each of the following risk factor: high-risk surgery defined as suprainguinal vascular, intraperitoneal or intrathoracic surgery; history of ischemic heart disease; history of congestive heart failure; history of stroke or transient ischemic attack; history of diabetes requiring insulin; creatinine level above 176.8µmol/L. This 6-point scale was published in 1999, but the quoted risks were based on a single center hospital with data collected from 1989-1994. This excluded emergency surgery and used CK-MB for myocardial infarction (MI) diagnosis⁵. The CCS has now created a pooled risk estimate from more modern external validation studies which included the use of troponins. As a result, the new RCRI risk estimates quoted for 30-day risk of perioperative MI, cardiac arrest, and death have increased to reflect modern data and provide more accurate risk estimates.

Another major difference from the AHA guideline is its focus on postoperative monitoring. The CCS guideline makes a strong recommendation on postoperative surveillance troponin measurements on high-risk patients. On the other hand, AHA guideline recommends checking troponin level only in the setting of clinical signs or symptoms suggestive of myocardial ischemia. However, postoperative analgesic medications can mask symptoms of ischemia. A majority of cardiac events would otherwise be undetected if measurements are only triggered by symptoms. The POISE trial, a large multicenter prospective cohort study of 8351 patients, found 65.3% of patients with perioperative MIs do not experience any ischemic symptoms⁶. Furthermore, another multicenter prospective cohort study (VISION) of 15,133 patients demonstrated that postoperative troponin T rise as little as 0.03ng/mL in the absence of symptoms still carries up to a 9.8% risk of 30-day mortality^7,8. While trials on mitigating this risk is underway^9,10, there is observational study evidence that intensification of cardiovascular therapy with aspirin and statin in the setting of postoperative troponin elevation is beneficial^6,11.

Finally, patients have increased risk of adverse cardiac outcomes in the setting of perioperative hypotension or bleeding^12-14. Thus, clear instructions to patients regarding which cardiovascular medications to continue or hold before surgery are important. These are covered in details in the CCS guideline. Specifically with regards to β-blocker initiation before non-cardiac surgery, prior to the publication of the landmark POISE trial¹², research based on the largely discredited DECREASE trial by Poldermans did suggest mortality benefit with β-blocker initiation¹⁵. However, most of the trials by Poldermans have since been brought into questions for scientific misconduct. Meta-analysis of trials of β-blocker initiation within 1 day or less before non-cardiac surgery (excluding DECREASE trial) found lower risk of perioperative MI, at the expense of higher risk of death and stroke¹⁶. Therefore, the CCS guideline makes a strong recommendation against β-blocker initiation within 24 hours of non-cardiac surgery (High-Quality Evidence). Currently there is insufficient data to comment on the effects of β-blockade started two or more days prior to surgery. For patients who take β-blocker chronically, observational study data suggests that withholding β-blocker preoperatively may be associated with harm¹⁷. However, if the patient is hypotensive before surgery, the CCS guideline recommends decreasing or holding the dose of the β-blocker before surgery.

What we recommend

We follow the CCS 2016 guideline on cardiac risk assessment and management in patients undergoing non-cardiac surgery. An algorithm is available in the paper² (View with CPSBC or UBC). Important practical points to note:

• Use the RCRI for assessment of perioperative cardiac risk. However, we do not use the risk estimates from the original data that derived the RCRI because it underestimates risk. Based on the new RCRI risk estimates², risk of 30-day MI, cardiac arrest, or death after non-cardiac surgery for a RCRI score of 0 is 3.9%, score of 1 is 6.0%, score of 2 is 10.1%, score of 3 and higher is 15.0%.
• Patients with an elevated cardiac risk as defined in the algorithm (age≥ 65 years, RCRI ≥ 1, or age 45-64 years with significant cardiovascular disease), should not have routine stress tests ordered, but instead have a preoperative BNP or NT-proBNP ordered for further risk stratification.
• For those with a BNP ≥ 92 mg/L or NT-proBNP ≥ 300 ng/L, or when these tests are not available, we do postoperative surveillance troponin in higher cardiac risk patients regardless of symptoms on postoperative days 0 to 3. When the postoperative troponin is positive, consider referral to Internal Medicine or Cardiology.
• Provide clear instructions to patients regarding which cardiovascular medications to continue or hold before surgery to avoid perioperative hypotension and bleeding. (i.e. hold angiotensin-converting enzyme (ACE) inhibitors, do not start new β-blockers but continue chronic ones if patient is not hypotensive, and refer to the CCS guideline for further cardiovascular medication management and to the Thrombosis Canada app for perioperative anticoagulant management)
• For those who had a troponin elevation postoperatively, even without clinical signs and symptoms of myocardial ischemia, we suggest the following:
  1. ASA 81mg once daily (without loading dose needed) should be started, provided hemostasis is achieved (Strong Recommendation; Moderate-Quality Evidence).
  2. A statin should also be started. (Strong Recommendation; Moderate-Quality Evidence).
  3. If patient is hypertensive and without acute renal dysfunction, preference should be made to using an ACE inhibitor or angiotensin II receptor blocker (ARB) for blood pressure control.
  4. There should be follow-up after discharge by Internal Medicine or Cardiology.

Acknowledgement

We would like to thank Dr. Rose Hatala for her helpful feedback and comments.

Resources

1. http://thrombosiscanada.ca/?page_id=502&calc=perioperativeAnticoagulantAlgorithm
2. http://www.ccs.ca/en/guidelines-library

References

1. Fleisher LA, Fleischmann KE, Auerbach AD, et al. 2014 ACC/AHA guideline on perioperative cardiovascular evaluation and management of patients undergoing noncardiac surgery: Executive summary: A report of the american college of cardiology/american heart association task force on practice guidelines. Circulation. 2014;130(24):2215-2245. (View with CPSBC or UBC) DOI: 1016/j.jacc.2014.07.944
2. Duceppe E, Parlow DJ, MacDonald P, et al. Canadian cardiovascular society guidelines on perioperative cardiac risk assessment and management for patients undergoing noncardiac surgery. Can J Cardiol. 2017;33(1):17-32. (View with CPSBC or UBC) DOI: 1016/j.cjca.2016.09.008
3. Etchells E, Meade M, Tomlinson G, Cook D. Semiquantitative dipyridamole myocardial stress perfusion imaging for cardiac risk assessment before noncardiac vascular surgery: A meta-analysis. J Vasc Surg. 2002;36(3):534-540. (Request with CPSBC or view UBC) DOI: 1067/mva.2002.126563
4. Rodseth RN, Biccard BM, Le Manach Y, et al. The prognostic value of pre-operative and post-operative B-type natriuretic peptides in patients undergoing noncardiac surgery: B-type natriuretic peptide and N-terminal fragment of pro-B-type natriuretic peptide: A systematic review and individual patient data meta-analysis. J Am Coll Cardiol. 2014;63(2):170-180. (View with CPSBC or UBC) DOI: 1016/j.jacc.2013.08.1630
5. Lee TH, Marcantonio ER, Mangione CM, et al. Derivation and prospective validation of a simple index for prediction of cardiac risk of major noncardiac surgery. Circulation. 1999;100(10):1043-1049. (View with CPSBC or UBC) DOI: 10.1161/01.CIR.100.10.1043
6. Devereaux PJ, Xavier D, Pogue J, et al. Characteristics and short-term prognosis of perioperative myocardial infarction in patients undergoing noncardiac surgery: A cohort study. Ann Intern Med. 2011;154(8):523-528. (Request with CPSBC or view UBC) DOI: 10.7326/0003-4819-154-8-201104190-00003
7. Devereaux P, Chan M, Alonso-Coello P, et al. Association Between Postoperative Troponin Levels and 30-Day Mortality Among Patients Undergoing Noncardiac Surgery. JAMA. 2012;307:2295-2304. (Request with CPSBC or view UBC) DOI: 10.1001/jama.2012.5502
8. Botto F, Alonso-Coello P, Chan MT, et al. Myocardial injury after noncardiac surgery: A large, international, prospective cohort study establishing diagnostic criteria, characteristics, predictors, and 30-day outcomes. Anesthesiology. 2014;120(3):564-578. (View with CPSBC or UBC) DOI: 1097/ALN.0000000000000113
9. gov. Management of myocardial injury after noncardiac surgery trial (MANAGE). https://clinicaltrials.gov/ct2/show/NCT01661101. Accessed 11/01, 2016. (View)
10. gov. Study of ticagrelor versus aspirin treatment in patients with myocardial injury post major non-cardiac surgery (INTREPID). https://clinicaltrials.gov/ct2/show/NCT02291419. Accessed 11/01, 2016. (View)
11. Foucrier A, Rodseth R, Aissaoui M, et al. The long-term impact of early cardiovascular therapy intensification for postoperative troponin elevation after major vascular surgery. Anesth Analg. 2014;119(5):1053-1063. (View with CPSBC or UBC) DOI: 1213/ANE.0000000000000302
12. Devereaux PJ, Yang H, Yusuf S, et al. Effects of extended-release metoprolol succinate in patients undergoing non-cardiac surgery (POISE trial): a randomised controlled trial. The Lancet. 2008;371:1839-1847. (View with CPSBC or UBC) DOI: 1016/S0140-6736(08)60601-7
13. Devereaux PJ, Mrkobrada M, Sessler DI, et al. Aspirin in patients undergoing noncardiac surgery. N Engl J Med. 2014;370(16):1494-1503. (Request with CPSBC or view UBC) DOI: 1056/NEJMoa1401105
14. Roshanov PS, Rochwerg B, Patel A, et al. Withholding versus continuing angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers before noncardiac surgery: An analysis of the vascular events in noncardiac surgery patients cohort evaluation prospective cohort. Anesthesiology. 2017;126(1):16–27. (View with CPSBC or UBC) DOI: 1097/ALN.0000000000001404
15. Poldermans D, Boersma E, Bax JJ, et al. The effect of bisoprolol on perioperative mortality and myocardial infarction in high-risk patients undergoing vascular surgery. Dutch echocardiographic cardiac risk evaluation applying stress echocardiography study group. N Engl J Med. 1999;341(24):1789-1794. (View)
16. Wijeysundera DN, Duncan D, Nkonde-Price C, et al. Perioperative beta blockade in noncardiac surgery: A systematic review for the 2014 ACC/AHA guideline on perioperative cardiovascular evaluation and management of patients undergoing noncardiac surgery: A report of the american college of cardiology/american heart association task force on practice guidelines. Circulation. 2014;130(24):2246-2264. (View)
17. Wallace AW, Au S, Cason BA. Association of the pattern of use of perioperative beta-blockade and postoperative mortality. Anesthesiology. 2010;113(4):794-805. (View)

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