Myocardial Injury After Noncardiac Surgery

Educational Objectives

The goal of this program is to improve the management of perioperative cardiac events in noncardiac surgery. After hearing and assimilating this program, the clinician will be better able to:

1. Recognize risk factors for major and nonmajor perioperative cardiac events.

2. Implement protocols for detection of nonmajor perioperative cardiac events.

3. Assess preoperative functional status of patients.

Summary

Background: major postoperative cardiac events experienced by 1% to 4% of surgical patients (defined as myocardial infarction [MI] with changes on electrocardiography [ECG] and symptoms, death, need for revascularization associated with myocardial event, or stent thrombosis); number of nonmajor postoperative cardiac events likely large (eg, troponin leaks); major postoperative cardiac events common cause of death; prevalence of coexisting disease in surgical patients increasing (eg, hypertension, hyperlipidemia, diabetes mellitus, obesity)

Classic acute MI in perioperative period of noncardiac surgery: can involve sympathetic hyperactivity, hemodynamic instability, tachycardia, or hypertension leading to coronary vasoconstriction; rupture of plaque can lead to acute MI; restenosis of stent possible

Type 2 MI in perioperative period of noncardiac surgery: characterized by mismatch of supply and demand leading to troponin leak and injury to myocardial cells without complete coronary closing; immediate intervention generally not required; many nonischemic events involving troponin leak can contribute to death

American College of Cardiology and American Heart Association (AHA) 2014 guidelines (Fleisher et al 2014): chance of major cardiac event in patient at low risk <1%; risk for major event increases with increasing level of risk; emergency surgery — must proceed regardless of risk; urgent surgery — some optimization allowed, but operation should proceed as quickly as possible; elective surgery — can proceed relatively rapidly in patient at low risk; in patient at higher risk, risk factors and functional status should be assessed

Study of risk for cardiac event in healthy patients: investigated risk for any type of cardiac event in patients undergoing noncardiac surgery in National Surgical Quality Improvement Program database; patients with American Society of Anesthesiologists (ASA) classification 1 or 2 without cardiac risk factors; found combined incidence of stroke and MI 0.07%; incidence higher for neurosurgery, thoracic surgery, urology, and vascular surgery (≈0.15%); rate of mortality low; odds ratio for myocardial event 18 times higher in patients aged >80 yr (even healthy patients); duration of case >6 hr associated with odds ratio 3 times higher

Risk for cardiac events in patients by number of risk factors: risk for cardiac death in patient with no risk factors 0.4%, with 1 risk factor ≈1%, and with 2 risk factors 2.5%; in patient with 2 risk factors, risk for MI, pulmonary edema, arrest related to ventricular fibrillation, or complete heart block ≈3%

Time frame for cardiac intervention in patient with MI: gold standard established by Medicare for interventional cardiology to achieve “door to device” in patient presenting to emergency department (ED) with ST-elevation MI within 90 min; inpatient metrics not considered by Medicare when determining door-to-device times for facility; for many inpatients, time >90 min (identifying events in inpatients and initiating therapy more difficult compared with patients in ED); speaker recommends consideration of process in postanesthesia care unit to start definitive treatment in patients experiencing cardiac events

Patients with sleep apnea: management of airway more complicated; risk for noncardiac events higher; emerging evidence suggests risk for atrial fibrillation, cardiac arrest, and heart failure higher because of strain on right side of heart; ASA and American Academy of Sleep Medicine recommend preoperative assessment and optimization; STOP-BANG tool available for stratification of risk for sleep apnea; Abdelsattar et al (2015) investigated effect of untreated sleep apnea in patients undergoing general and vascular surgery; found incidence of any cardiopulmonary complication in patients without sleep apnea 4.9% and in those with untreated sleep apnea 6%; in patients with treated sleep apnea, risk slightly below baseline; untreated sleep apnea driver of increased risk (rate of postoperative acute MI nearly doubled)

Perioperative interventions that clearly confer no benefit (Fleisher et al 2014): include prophylactic use of intravenous nitroglycerine, routine intraoperative use of transesophageal echocardiography, and routine use of pulmonary artery catheters

Elevated troponin level: Botto et al (2014) investigated large cohort of patients aged >45 yr admitted for noncardiac surgery; levels of troponin measured postoperatively; found troponin levels elevated in large number of patients; many had no symptoms or changes on ECG; very few had chest discomfort or pulmonary edema; only 15% had any symptoms; only 34% had any changes on ECG; at many facilities, troponin levels not routinely measured in every patient after surgery; after noncardiac surgery, higher peak troponin levels associated with increasing risk for death; patients with high troponin levels also at risk for congestive heart failure, stroke, and nonfatal cardiac arrest; age >75 yr identified as risk factor; combination of age >75 yr and changes on ECG identified as huge factor in mortality rate; many patients lacked traditional evidence of MI

Long-term outcomes: patients with type 1 MI — likely to undergo intervention; in appropriately treated patients, 5-yr rate of survival 60%; patients with type 2 MI — not candidates for intervention because of lack of coronary event; management difficult; 5-yr rate of survival lower; death can occur as result of many different events; elevated troponin marker of many other illnesses

Effectiveness of interventions for minor cardiac events: how to address elevated troponin levels and improve survival curve not determined; POISE-2 trial (Devereaux et al 2014) — 2 × 2 trial of aspirin and clonidine compared with placebo; in patients undergoing noncardiac surgery, neither aspirin nor clonidine significantly affected rate of death or nonfatal MI; aspirin associated with increase in risk of bleeding; clonidine, with increase in risk for hypotension and bradycardia

AHA recommendations for major cardiac events: continue β- blockers, but do not start them on day of surgery; continue statins; do not give clonidine; continue angiotensin-converting enzyme (ACE) inhibitors; if ACE inhibitor held because of problem with blood pressure, restart it as soon as possible; balance benefits of aspirin against risk of bleeding

Functional status: usually assessed subjectively based on ability of patient to perform various tasks; Wijeysundera et al (2018) assessed ≈1400 patients admitted for elective noncardiac surgery using subjective assessment of functional status, Duke Activity Status Index (DASI), cardiopulmonary exercise testing, and measurement of preoperative concentrations of pro-B-type natriuretic peptide (BNP); DASI includes 12 questions about ability to perform various activities; positive responses worth various metabolic equivalents (METs); study found added predictive value of subjective assessment lacking; subjective assessment unable to identify patients with functional status <4 METs; DASI most valuable assessment tool for predicting 30-day risk for MI or death; also appeared to predict risk for nonmajor events (eg, troponin leaks); elevated BNP level unable to predict risk for MI, but able to predict risk for troponin leak; findings of cardiopulmonary exercise testing not predictive for death or acute MI, but highly predictive for which patients likely to require admission to intensive care unit, experience respiratory failure, have surgical complication, or develop surgical site infection

Canadian model: identify patients aged >18 yr with significant risk for heart disease, undergoing noncardiac surgery, and requiring overnight admission; determine urgency of surgery; proceed with emergent surgery; postoperative assessment of troponin level suggested in high-risk patients; for urgent cases, perform preoperative cardiac testing if patient unstable or if undiagnosed severe cardiovascular condition suspected, and assess troponins postoperatively; assessment of functional status not recommended before elective surgery; assess BNP preoperatively and troponin postoperatively

Readings

Abdelsattar ZM et al: The impact of untreated obstructive sleep apnea on cardiopulmonary complications in general and vascular surgery: a cohort study. Sleep 2015 Aug 1;38(8):1205-10; Botto F et al: Myocardial injury after noncardiac surgery: a large, international, prospective cohort study establishing diagnostic criteria, characteristics, predictors, and 30-day outcomes. Anesthesiology 2014 Mar;120(3):564-78; Devereaux PJ et al: Aspirin in patients undergoing noncardiac surgery. N Engl J Med 2014 Apr 17;370(16):1494-503; Devereaux PJ et al: Clonidine in patients undergoing noncardiac surgery. N Engl J Med 2014 Apr 17;370(16):1504-13; Fleisher LA et al: 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 Dec 9;130(24):e278-333; Wijeysundera DN et al: Assessment of functional capacity before major non-cardiac surgery: an international, prospective cohort study. Lancet 2018 Jun 30;391(10140):2631-40.

Disclosures

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

Acknowledgements

Dr. Surgenor was recorded at the 24th Annual Vermont Perspectives in Anesthesia, held March 6-10, 2019, in Stowe, VT, and presented by the Robert Larner, MD, College of Medicine at the University of Vermont, Office of Continuing Medical Education. For information about upcoming CME activities from this sponsor, please visit med.uvm.edu/cme. The Audio Digest Foundation thanks the speakers and the Robert Larner, MD, College of Medicine at the University of Vermont, Office of Continuing Medical Education, 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 0 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 0 CE contact hours.

Lecture ID:

AN613201

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.