Preoperative cardiac risk assessment

Diseases

Overview

Introduction

Approximately 27 million patients undergo noncardiac surgery every year in the US.[1] Of those, about 50,000 have a perioperative myocardial infarction (MI). Furthermore, over one half of the 40,000 perioperative deaths each year are caused by cardiac events.[2] Most perioperative cardiac morbidity and mortality is related to MI, heart failure, or arrhythmias. Patients over 65 years of age are at higher risk of cardiac disease, cardiac morbidity, and death. Considering that this patient population will greatly increase over the coming decades, the number of patients with significant perioperative cardiac risk undergoing noncardiac surgery can be expected to increase globally. Patients with congenital heart disease, especially those with unrepaired lesions or a residual lesion burden and compromised cardiovascular status, also require individualized perioperative management.

Preoperative cardiac risk assessment and perioperative management emphasize the detection, characterization, and treatment of coronary artery disease (CAD), left ventricular (LV) systolic dysfunction, and significant arrhythmias in appropriate patients. The American Heart Association/American College of Cardiology (AHA/ACC) guidelines for managing adults with congenital heart disease recommend a stepwise approach to preoperative cardiac assessment, but there are currently no guidelines for comprehensive perioperative care of children with congenital heart disease undergoing noncardiac surgery.[3] [4] Patients with known or suspected CAD, arrhythmias, history of heart failure, or current symptoms consistent with these conditions should also undergo assessment. In people ages ≥50 years, a more extensive history and physical exam is warranted.

The purpose of individual preoperative cardiac risk assessment is to:[5][6] [7]

Assess the medical status of the patient and the cardiac risks posed by the planned noncardiac surgery
Recommend appropriate strategies to reduce the risk of cardiac problems over the entire perioperative period, and to improve long-term cardiac outcomes.

The main overall goals of assessment are to:

Identify patients at increased risk of an adverse perioperative cardiac event
Identify patients with a poor long-term prognosis due to cardiovascular disease. Even though the risk at the time of noncardiac surgery may not be prohibitive, appropriate treatment will affect long-term prognosis.

The nature of the evaluation should be individualized to the patient and the specific clinical scenario:

Patients presenting with an acute surgical emergency require only a rapid preoperative assessment, with subsequent management directed at preventing or minimizing cardiac morbidity and death. Such patients can often be more thoroughly evaluated after surgery.
Patients undergoing an elective procedure with no surgical urgency can undergo a more thorough preoperative evaluation.

Stepwise management approach

Eight steps to optimize perioperative outcomes:[8]

1. Assess clinical features

The history and physical exam should help to identify markers of cardiac risk and assess the patient's cardiac status.
High-risk cardiac conditions include recent myocardial infarction (MI), decompensated heart failure, unstable angina, symptomatic arrhythmias, and symptomatic valvular heart disease.[9]

2. Evaluate functional status

Patients who are able to exercise on a regular basis without limitations generally have sufficient cardiovascular reserve to withstand stressful operations.

3. Consider surgery-specific risk

The type of surgery has important implications for perioperative risk. Noncardiac surgery can be stratified into high-risk, intermediate-risk, and low-risk categories (see below 'risk stratification according to type of noncardiac surgery').

4. Decide whether further noninvasive evaluation is needed

Patients who are at low cardiac risk based on clinical features and functional status, and are undergoing low-risk surgery, do not generally require further evaluation.
Patients who are at high cardiac risk based on clinical features, have poor functional status, and are being considered for high-risk noncardiac surgery may benefit from further evaluation.

5. Decide when to recommend invasive evaluation

Indications for preoperative coronary angiography are similar to those in the nonoperative setting and include patients with evidence of high cardiac risk based on noninvasive testing, angina unresponsive to adequate medical therapy, unstable angina, and proposed intermediate-risk or high-risk noncardiac surgery after equivocal noninvasive test results.
Angiography and revascularization are not routinely indicated for patients with stable coronary artery disease (CAD).

6. Optimize cardiovascular risk factors, lifestyle interventions, and medical therapy

Control of cardiovascular risk factors, including hypertension, dyslipidemia, and diabetes, is important before noncardiac surgery.[5]
Patients should be given optimal medical therapy, both perioperatively and in the long term, based on their underlying cardiac condition.
Lifestyle modifications before noncardiac surgery may reduce the risk of perioperative complications, but their impact on cardiovascular complications has not been adequately studied. Smoking cessation prior to surgery has the most robust evidence base.[5]

7. Perform appropriate perioperative surveillance

In patients with known or suspected CAD, the possibility of perioperative ischemia or MI can be estimated based on the magnitude of biomarker elevation, new ECG abnormalities, hemodynamic instability, and the quality and intensity of chest pain or other symptoms.

8. Design maximal long-term therapy

Assessment for hypercholesterolemia, smoking, hypertension, diabetes mellitus, physical inactivity, peripheral vascular disease, cardiac murmurs, arrhythmias, conduction abnormalities, and/or perioperative ischemia may lead to evaluation and treatments that reduce future cardiovascular risk.

History and physical examination

The patient history should aim to:

Identify cardiac conditions (e.g., recent or past myocardial infarction, decompensated heart failure, prior unstable angina, significant arrhythmias, valvular heart disease)
Identify serious comorbid conditions (e.g., diabetes mellitus, peripheral vascular disease, stroke, renal insufficiency, pulmonary disease)
Determine patient's functional capacity
Document all current medications, allergies, tobacco use, and physical exercise habits.

On physical exam, patients with severe aortic stenosis, elevated jugular venous pressure, pulmonary edema, and/or third heart sound are at high surgical risk.

Functional capacity assessment

The functional capacity of the patient to perform common daily activities has been shown to correlate well with maximum oxygen uptake by treadmill testing.[6] On assessment, patients with <4 metabolic equivalents (METS) are considered to have poor functional capacity and are at relatively high risk of a perioperative event, while patients with >10 METS have excellent functional capacity and are at very low risk of perioperative events, even if they have known coronary artery disease. Patients with a functional capacity of 4 to 10 METS are considered to have fair functional capacity and are generally considered at low risk of perioperative events.

1 MET

Eat, dress, use the toilet
Walk indoors around the house
Walk on level ground at 2 mph (3.2 km/hour)
Perform light housework such as washing dishes.

4 METs

Climb a flight of stairs (usually 18-21 steps)
Walk on level ground at 4 mph (6.4 km/hour)
Run short distances
Perform vacuuming or lift heavy furniture
Play golf or doubles tennis.

>10 METs

Swimming
Singles tennis
Basketball
Skiing.

Cardiac risk stratification using clinical predictors and risk models

The presence of ≥1 of the following active cardiac conditions is considered high risk, mandates intensive management, and may result in delay or cancellation of surgery unless the surgery is urgent.[6]

Unstable coronary syndromes
- Unstable or severe angina
- Recent myocardial infarction (MI)
Decompensated heart failure
Significant arrhythmias
- Mobitz II atrioventricular block
- Third-degree atrioventricular block
- Symptomatic ventricular arrhythmias
- Supraventricular arrhythmias (including atrial fibrillation) with uncontrolled ventricular rate (heart rate >100 bpm at rest)
- Symptomatic bradycardia
- Newly recognized ventricular tachycardia.
Severe valvular disease
- Severe aortic stenosis (mean pressure gradient >40 mmHg, aortic valve area <1.0 cm², or symptomatic)
- Symptomatic mitral stenosis (progressive dyspnea on exertion, exertional presyncope, or heart failure).

Patients are considered at intermediate risk if there are no active cardiac conditions as defined above, but the patient has 1 or more of the following clinical risk factors:[6]

History of heart disease
History of compensated or prior heart failure
History of cerebrovascular disease
Diabetes mellitus
Renal insufficiency.

Patients are considered at low risk if the active cardiac conditions and clinical risk factors defined above are absent.[6]

Diagnostic tests can be used to refine the risk assessment. Some allow for risk stratification to be reassessed based on the test results (e.g., stress testing).

Revised cardiac risk index (RCRI):

The revised cardiac risk index uses 6 variables to predict perioperative cardiovascular risk:[10]

High-risk surgery (intrathoracic, intra-abdominal, or suprainguinal vascular)
Ischemic heart disease (defined as a history of MI, pathologic Q waves on the ECG, use of nitrates, abnormal stress test, or chest pain secondary to ischemic causes)
Presence of congestive heart failure
History of cerebrovascular disease
Diabetes mellitus requiring insulin therapy
Preoperative serum creatinine level higher than 2 mg/dL.

Each of the 6 risk variables are assigned 1 point. Patients with 0, 1, or 2 risk factor(s) are assigned to RCRI classes I, II, and III, respectively. Patients with 3 or more risk factors are class IV and considered at high risk. Each class translates into 0.4% (class I), 0.9% (class II), 6.6% (class III), and 11% (class IV) risk for major cardiac events. Overall, the RCRI performs well in stratifying patients at low compared with high risk for all types of noncardiac surgery, but appears less accurate in patients undergoing vascular surgery.

Vascular Study Group of New England cardiac risk index (VSG-CRI):

The VSG-CRIVSGNE risk index was developed specifically for patients undergoing vascular surgery and applies to carotid endarterectomy, lower extremity bypass, and endovascular and open repair of nonruptured abdominal aortic aneurysms.[11] The independent predictors of adverse cardiac events (MI, arrhythmia, and heart failure, but not mortality) were increasing age, smoking, insulin-dependent diabetes mellitus, coronary artery disease, coronary heart failure, abnormal cardiac stress test, long-term beta-blocker therapy, chronic obstructive pulmonary disease, and creatinine ≥1.8 mg/dL. Prior cardiac revascularization was protective. The VSG-CRI predicted increasing levels of risk for cardiac events, ranging from 2.6% for the lowest risk scores (0-3) up to 14.3% for the highest risk score (7-8). This risk index performs better than RCRI for those undergoing vascular surgery.[11]

Images

Cardiac evaluation and care algorithm for noncardiac surgery
Preoperative risk assessment and postoperative monitoring flow diagram. If suspected undiagnosed severe obstructive intracardiac abnormality or severe PHTN a preoperative echocardiogram is recommended. If possible unstable cardiac condition (e.g., unstable angina) then risks and benefits of delaying, canceling, or proceeding with surgery need to be discussed with the patient. RCRI score (each worth 1 point): history of coronary artery disease, cerebrovascular disease, congestive heart failure, preoperative insulin use, preoperative creatinine > 177 micromoles/L, and high-risk surgery (i.e., intraperitoneal, intrathoracic, or suprainguinal vascular surgery). BNP, brain natriuretic peptide; ECG, electrocardiogram; NT-proBNP, N-terminal pro-brain natriuretic peptide; PACU, postanesthesia care unit; PHTN, pulmonary hypertension; RCRI, Revised Cardiac Risk Index

Citations

Key Articles

Halvorsen S, Mehilli J, Cassese S, et al. 2022 ESC guidelines on cardiovascular assessment and management of patients undergoing non-cardiac surgery. Eur Heart J. 2022 Oct 14;43(39):3826-924.[Abstract][Full Text]
Fleisher LA, Fleischmann KE, Auerbach AD, 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. J Am Coll Cardiol. 2014;64:e77-e137.[Abstract][Full Text]
Duceppe E, Parlow J, MacDonald P, et al. Canadian Cardiovascular Society guidelines on perioperative cardiac risk assessment and management for patients who undergo noncardiac surgery. Can J Cardiol. 2017 Jan;33(1):17-32.[Abstract][Full Text]

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