Which Patient Should Have a Preoperative Cardiac Evaluation (Stress Test)?

INTRODUCTION

Preoperative cardiovascular risk assessment attempts to prospectively identify at-risk patients and allows targeted management to reduce perioperative cardiac complications. These complications include both “demand” events, in which perioperative stress increases myocardial oxygen requirements to a level that cannot be met because of fixed obstructive coronary artery disease (CAD) or low perfusion pressure, and true “acute coronary syndromes” (ACS) with occlusive plaque rupture, likely due, in part, to perioperative inflammation and an associated prothrombotic state. ^,

A careful history and physical examination are the cornerstone for perioperative cardiovascular risk assessment. Epicardial obstructive CAD sufficient to cause demand-related biomarker release can be identified by cardiac stress testing and coronary angiography. Nevertheless, before pursuing these tests preoperatively, it is essential to determine whether that test will lead to a meaningful short- or long-term change in the management. This change in management includes not just the question of coronary revascularization but also decisions on the extent of surgery or the surgical approach, location of the surgery (i.e., outpatient or monitored facility), type of anesthesia, timing of the surgery, or consideration of nonsurgical alternatives.

Perioperative cardiovascular assessment has evolved to include risk prediction tools and biomarkers to identify at-risk patients and ischemia evaluation using stress testing, when indicated, to identify hemodynamically significant CAD followed by medical optimization or possible revascularization. Revolutionary changes in cardiovascular medical management, together with advances in surgical and anesthetic techniques, have significantly reduced operative morbidity and mortality rates; event rates have decreased from approximately 10% to 15% in intermediate-risk patients three decades ago to approximately 5% in contemporary “at-risk” patients (i.e., those with risk factors for or known CAD) and to approximately 1.5% in unselected noncardiac surgery patients. ^, Anesthesia-related deaths occur in less than 1 in 100,000 noncardiac procedures. This reduction in risk likely attenuates any potential benefit of preoperative revascularization, and current guidelines do not recommend routine stress testing or revascularization in stable patients. Consequently, the role of preoperative cardiac stress testing has been reduced to the identification of extremely high-risk patients, such as those with significant left main disease, for whom preoperative revascularization may provide a benefit independent of the noncardiac surgery.

ASSESSING CARDIAC RISK: OPTIONS/EVALUATION STRATEGIES

As we integrate the available data into standard practice, the following key issues emerge:

1.
Understanding risk factor implications, including risk prediction tools and biomarkers
2.
Understanding absolute contraindications to nonemergent surgical procedures
3.
Understanding medical treatment options independent of revascularization that can significantly affect patient outcome
4.
Understanding the risks and benefits of revascularization in the preoperative period
5.
Appropriate testing for ischemia evaluation

PERIOPERATIVE CARDIAC RISK STRATIFICATION: RISK PREDICTION TOOLS

Risk prediction tools can enable prospective quantification of perioperative cardiovascular risk and have been recommended by current guidelines ( Table 3.1 ). In the Revised Cardiac Risk Index (RCRI), patients are divided into quartiles of predicted risk for in-hospital myocardial infarction (MI), pulmonary edema, ventricular fibrillation or primary cardiac arrest, complete heart block, or cardiac death based on six independent risk factors ( https://qxmd.com/calculate/calculator_195/revised-cardiac-risk-index-lee-criteria ). RCRI is the simplest tool to use, and patients with at least two risk predictors are considered to have elevated risk. The MI or Cardiac Arrest (MICA) risk index and the American College of Surgeons Surgical Risk Calculator (ACS-SRC) were developed from the National Surgical Quality Improvement Program database and are accessible at https://qxmd.com/calculate/calculator_245/gupta-perioperative-cardiac-risk and https://riskcalculator.facs.org/RiskCalculator/index.jsp , respectively. The ACS-SRC is the most comprehensive, web-based tool. The c -statistic of these risk prediction tools varies from 0.76 to 0.80 for RCRI, 0.87 to 0.88 for MICA, and 0.80 to 0.94 for ACS-SRC.

TABLE 3.1

Recommendations From Societies for Perioperative Cardiac Risk Assessment and Management

	2014 ACC/AHA and 2016 ACC/AHA focus update	2014 ESC/ESA	2017 CCS
Risk prediction tools	Recommend use of RCRI, MICA, or ACS-SRC for prediction of MACE (Class IIa/LOE: B)	Recommend use of RCRI, MICA, or ACS-SRC for prediction of MACE (Class I)	Favor RCRI over other cardiovascular risk prediction tools (Conditional recommendation; low-quality evidence)
Biomarkers	Uncertain usefulness of postoperative troponin surveillance or ECGs in asymptomatic patients at high risk for MI (Class IIb/LOE: B) BNP may be helpful in assessing patients with HF preoperatively or for diagnosing HF postoperatively in high-risk patients	May consider measuring BNP and hs-Tn perioperatively in high-risk patients (i.e., functional capacity ≤4 METS or RCRI >1 for vascular surgery, and >2 for nonvascular surgery or postoperative surgical Apgar score <7) (Class IIb/LOE: B)	Recommend daily troponins for 48–72 hours after noncardiac surgery and ECG immediately after the surgery in the recovery room if baseline risk of 30-day cardiovascular death or nonfatal MI is >5% (i.e., preoperative NT-proBNP ≥300 mg/L or BNP ≥92 mg/L or, if these biomarkers are not available, RCRI score ≥1, age 45–64 years with significant cardiovascular disease, or age ≥65 years) (Strong recommendation; moderate-quality evidence)
Beta-blockers	Continue beta-blockers if patient taking them chronically Do not initiate beta-blockers within 24 hours of surgery If RCRI ≥3, reasonable to start beta-blockers (Class IIb/LOE: B)Reasonable to start beta-blockers if intermediate- or high-risk myocardial ischemia noted in preoperative risk stratification tests (Class IIb/LOE: C)	Continue beta-blockers if patient taking it chronically Do not initiate beta-blockers within 24 hours of surgery May consider preoperative beta-blockers if ≥2 clinical risk factors or ASA ≥3 if high-risk surgery (Class IIb/LOE: B) and if known CAD or myocardial ischemia (Class IIb/LOE: B) - Atenolol or bisoprolol may be first choice (Class IIb/LOE: B)	Continue beta-blockers if patient taking it chronically Do not initiate beta-blockers within 24 hours of surgery
Statins	Continue statins perioperatively (Class I/LOE: B)Perioperative initiation of statins may be considered in patients undergoing elevated risk procedures in accordance with guideline-directed medical therapy (Class IIb/LOE: C) For patients undergoing vascular surgery, reasonable to initiate statins preoperatively (Class IIb/LOE: B)	Continue statins perioperatively (Class I/LOE: C) Favor statins with a long half-life (e.g., atorvastatin) or extended-release formulations (e.g., lovastatin) if oral intake not feasible in the immediate postoperative period For patients undergoing vascular surgery, initiate statins ideally ≥2 weeks before surgery (Class IIa/LOE: B)	Evidence too weak to make recommendation on initiation of statins Continue statins perioperatively (Strong recommendation; moderate-quality evidence)
Antiplatelet therapy	Initiation or continuation of aspirin not beneficial in patients without significant risk factors or known CAD (Class III/LOE: B) Continue aspirin in patients with coronary stents unless bleeding risk is exceptionally high Continue DAPT in patients with coronary stents unless the bleeding risk is prohibitive (Class I/LOE: C)	Continuation of aspirin should be individualized (Class IIb/LOE: B) Continue aspirin in patients with coronary stents unless bleeding risk is exceptionally high	Recommend against initiation of aspirin for prevention of perioperative cardiac events (Strong recommendation; high-quality evidence) Recommend against continuation of aspirin perioperatively except in patients with coronary stents or those undergoing carotid endarterectomy (Strong recommendation; high-quality evidence)
ACEI/ARB	Reasonable to continue ACEI/ARB perioperatively If discontinued, reasonable to resume when feasible	Withhold ACEI/ARB 24 hours before noncardiac surgery unless the patient is stable and has left ventricular systolic dysfunction (Class IIa/LOE: C) Resume ACEI/ARB on postoperative day 2 if the patient is hemodynamically stable Initiate ACEI/ARB ≥1 week before noncardiac surgery in stable patients with left ventricular dysfunction (Class IIa/LOE: C)	Withhold ACEI/ARB 24 hours before noncardiac surgery (Strong recommendation; low-quality evidence)
Coronary revascularization	Recommend against routine preoperative coronary revascularization in stable patients before noncardiac surgery (Class III/LOE: C)	May be considered in stable patients before nonurgent carotid endarterectomy (Class IIb/LOE: B) but not in stable patients before low-risk surgery (Class III/LOE: C)	Recommend against routine preoperative coronary revascularization in stable patients before noncardiac surgery (Strong recommendation; low-quality evidence)
Timing of surgery after PCI	Postpone elective surgery for a minimum of 30 days after BMS-PCI and 12 months after DES-PCI (6 months after DES-PCI in 2016 focus update) (Class IIb) and for at least 12 months after ACS (Class I)If surgery cannot be postponed beyond 3 months after PCI and P2Y ₁₂ inhibitor has to be interrupted perioperatively, continue aspirin perioperatively if the bleeding risk allows (Class IIb/LOE: C)	Postpone elective surgery for a minimum of 4 weeks after BMS-PCI and 6 months after new-generation DES-PCI, and for up to 1 year after ACS, irrespective of the revascularization strategy	No recommendation
Stress testing	Reasonable to forgo noninvasive testing with functional capacity >10 METS (Class IIa/LOE: B) or ≥4–10 METS (Class IIb/LOE: C) even if estimated to be at elevated risk Routine noninvasive stress testing not useful before low-risk noncardiac surgeries (Class III/LOE: B) May be reasonable to perform pharmacologic stress testing if elevated risk (≥1% risk of MACE) and poor or unknown functional capacity if it will impact decision making or perioperative care (Class IIb/LOE: C)	Routine noninvasive stress testing not useful before low-risk noncardiac surgeries (Class III/LOE: C) Recommend imaging stress testing with >2 clinical risk factors (RCRI) and poor functional capacity for high-risk surgery (Class I/LOE: C) May be considered if 1–2 clinical risk factors and poor functional capacity and high- or intermediate-risk surgery (Class IIa/LOE: C)	Recommend against stress testing (Strong recommendation; low-quality evidence) Recommend against exercise stress testing (Strong recommendation; low-quality evidence) Recommend against MPI and stress echocardiography (Strong recommendation; low- to moderate-quality evidence)
CPET	May be considered if unknown functional capacity and if planning high-risk procedure (Class IIb/LOE: B)	No recommendation	Not recommended (Strong recommendation; low-quality evidence)

ACC/AHA, American College of Cardiology/American Heart Association; ACEI/ARB , angiotensin-converting enzyme inhibitors/angiotensin II receptor blockers; ACS , acute coronary syndrome; ACS-SRC, American College of Surgeon’s Surgical Risk Calculator; ASA , American Society of Anesthesiologist’s physical status score; BMS , bare metal stent; BNP , B-type natriuretic peptide; CAD , coronary artery disease; CCS , Canadian Cardiovascular Society; CPET , cardiopulmonary exercise testing; DAPT , dual antiplatelet therapy; DES , drug eluting stent; ECG , electrocardiogram; ESC/ESA , European Society of Cardiology/European Society of Anesthesiology; HF , heart failure; hs-Tn , high sensitivity troponin; LOE , level of evidence; MACE , major adverse cardiovascular event; METS, metabolic equivalents; MI , myocardial infarction; MICA , myocardial infarction and cardiac arrest; MPI , myocardial perfusion imaging; NT-proBNP , N-terminal-proBNP; PCI , percutaneous coronary intervention; RCRI , revised cardiac risk index.

PERIOPERATIVE CARDIAC RISK STRATIFICATION: BIOMARKERS

Biomarkers such as troponin (see Chapter 62 ) and B-type natriuretic peptide (BNP; see Chapter 9 ) can improve preoperative cardiac risk stratification and have been recommended by the 2014 European Society of Cardiology/European Society of Anesthesiology (ESC/ESA) and the 2017 Canadian Cardiovascular Society (CCS) guidelines (see Table 3.1 ). ^, The Vascular events In noncardiac Surgery patIents cOhort evaluatioN (VISION) investigators reported that patients with elevated postoperative troponins within 30 days of noncardiac surgery have an increased risk for 30-day mortality, nonfatal cardiac arrest, heart failure, and stroke. ^, These investigators defined myocardial injury after noncardiac surgery (MINS) as a rise and/or fall of troponin of presumed ischemic etiology within 30 days of noncardiac surgery that may or may not meet the criteria for the universal definition of MI. The incidence of perioperative MIs has been reported to be 3% to 6%; it is estimated that approximately 93% of the episodes of MINS and 68% of the perioperative MIs would be unrecognized in the absence of troponin surveillance. Consequently, the ESC/ESA and CCS guidelines (but not the 2014 American College of Cardiology/American Heart Association [ACC/AHA] guidelines) recommend postoperative troponin surveillance in high-risk patients.

A meta-analysis including 2179 patients from 18 studies reported that preoperative BNP improved the risk stratification for death or nonfatal MI at 30 days (net reclassification index 20%) and at 180 days or more (net reclassification index 11%) after noncardiac surgery. A prospective cohort study consisting of 10,402 patients reported that elevated N-terminal proBNP (NT-proBNP) (defined as >100 pg/mL) was significantly associated with vascular death and MINS at 30 days after noncardiac surgery and also improved cardiac risk prediction in addition to RCRI (net absolute reclassification improvement of 258 per 1000 patients). In the METS (Measurement of Exercise Tolerance before Surgery) study, however, NT-proBNP was not predictive of 30-day MI or death.

EVIDENCE THAT SPECIFIC HIGH-RISK CONDITIONS DEMAND PREOPERATIVE ASSESSMENT AND INTERVENTION

The ACC/AHA guidelines for preoperative cardiac assessment also define four “major” risk factors that preclude nonemergent surgical procedures: active/recent unstable coronary syndrome, decompensated heart failure (HF), significant arrhythmia, and severe valvular disease.

Acute Coronary Syndrome

An active unstable coronary syndrome is, until proven otherwise, an ACS reflecting erosion or rupture of an atherosclerotic plaque. Patients with an ACS are at increased perioperative risk, and in such cases surgery should be delayed when possible. Retrospective electrocardiogram (ECG) analysis from the GUSTO-IIb (Global Use Of Strategies To Open occluded arteries in ACS) study demonstrated that mortality rates rise for 20 to 30 days after presentation, after which mortality rates stabilize. Another study confirmed this high risk within the first 30 days but noted the significant risk for postoperative mortality and MI extended at least 2 months after an MI. As such, the ACC/AHA guidelines recommend that at least 60 days should elapse after an MI, in the absence of a coronary intervention, before pursuing noncardiac surgery.

Decompensated Heart Failure

Although treatments for HF have advanced significantly in the past decade, survival benefits have been more prominent in patients with mild to moderate disease than in those with advanced HF. The 28-day case fatality rate in acute decompensated HF ranges from 9.2% to 12.1%. These rates, which exceed the expected cardiovascular event rates for the vast majority of elective surgical procedures, would almost certainly increase significantly with the hemodynamic and systemic stress of surgery. Early multivariate risk factor analyses confirmed that decompensated HF was associated with an increased risk of perioperative morbidity and mortality. Patients with nonischemic cardiomyopathy require optimization of the underlying pathology and careful monitoring of the volume status, cardiac medication adjustment, and monitoring for arrhythmias.

Perioperative cardiac risk indices include HF as an independent prognostic variable for perioperative complications. Patients with acute HF may have significantly higher risk for perioperative mortality compared to those with CAD. Although symptomatic HF is associated with negative perioperative outcomes, the effect of asymptomatic left ventricular (LV) dysfunction is not known. LV ejection fraction (EF) less than 30% is an independent predictor of worse perioperative outcomes; mortality rates are better in patients with HF with preserved EF, but these rates are still higher compared with those without HF. Diastolic dysfunction with or without systolic dysfunction has also been associated with a higher risk for major adverse cardiovascular events (MACE), longer length of stay, and postoperative decompensated HF.

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