Preoperative cardiac risk assessment

Overview

Introduction

Approximately 50 million patients undergo noncardiac surgery every year in the US.[1] Of those, about 750 per 100,000 people have a nonfatal perioperative myocardial infarction (MI). Fatal major cardiovascular and cerebrovascular events occur around 1.67% of cases.[1] Most perioperative cardiac morbidity and mortality is related to MI, heart failure, cardiogenic shock, or arrhythmias.[1]

Multiple cardiovascular risk factors are present in 45% of surgical inpatients age ≥45 years.[2] As the global population ages, the number of patients with significant perioperative cardiac risk undergoing noncardiac surgery can be expected to increase.

Preoperative cardiac risk assessment and perioperative management emphasize the detection, characterization, and management of cardiac disorders in appropriate patients. Patients with known or suspected coronary artery disease (CAD), arrhythmias, history of heart failure, or current symptoms consistent with these conditions should also undergo assessment. In people age ≥45 years, a more extensive history and physical exam is warranted.

The purpose of individual preoperative cardiac risk assessment is to:[2] [3][4] [5]

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 (e.g., cardiovascular death, acute heart failure, MI, or hemodynamically relevant arrhythmia)
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.

Patients are at highest risk of perioperative cardiac events in the first 30 days following surgery, but risk remains elevated for about 5 months.[5]

Stepwise management approach

Consider eight steps to optimize perioperative outcomes:[6]

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.[7]

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.[3] See Essential hypertension , Hypercholesterolemia , and Type 2 diabetes mellitus in adults .
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.[3] [8] See Smoking cessation .

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 be thorough and 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 drugs, allergies, tobacco and alcohol use, and lifestyle habits (including diet and physical exercise).

On physical exam, patients should be assessed for clinical signs suggestive of cardiac disorders including: elevated jugular venous distension, heart murmurs, and peripheral and pulmonary edema.[9]

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 exercise stress testing.[2] On assessment, patients with <4 metabolic equivalents (METS) are considered to have poor functional capacity and are at relatively high risk of an adverse perioperative cardiac event, while patients with >10 METS have excellent functional capacity and are at very low risk of such adverse events, even if they have known coronary artery disease. Patients with a functional capacity of 4 to 6 METS or 7 to 10 METS are considered to have moderate or good functional capacity, respectively, and are generally considered at low risk of adverse perioperative cardiac events.[10]

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

Several risk prediction models have been developed based on data from large cohorts. Risk calculators may be used in addition to, or as an alternative to, assessment of patient-related and surgery-related risk factors. There are no data to support the use of one risk index over another; some commonly used ones are:[2]

Revised cardiac risk index (RCRI)

The revised cardiac risk index uses 6 variables to predict perioperative cardiovascular risk:[11]

High-risk surgery (intrathoracic, intra-abdominal, or suprainguinal vascular)
Ischemic heart disease (defined as a history of myocardial infarction [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.

American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP)

A surgical risk calculator has been developed by the ACS NSQIP using 21 preoperative factors.[12] These factors include 20 patient characteristics (age, sex, functional class, emergency case, American Society of Anaesthesiologists class, corticosteroid use, presence of ascites within 30 days, systemic sepsis, ventilator dependence, presence of disseminated cancer, diabetes mellitus, hypertension, heart failure within 30 days, presence of dyspnea, current smoking status, history of severe COPD, need for dialysis, presence of acute renal failure, height, and weight) and type of procedure. This model had excellent performance for mortality (c-statistic = 0.944; Brier score = 0.011 [where scores approaching 0 are better]), morbidity (c-statistic = 0.816; Brier score = 0.069), and 6 additional complications (c-statistics >0.8).[12] The ACS NSQIP surgical risk calculator offers surgeons the ability to quickly and easily estimate important, patient-specific postoperative risks and present the information in a patient-friendly format.

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.[13] 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.[13]

Citations

Key Articles

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. Circulation. 2024 Nov 5;150(19):e351-442.[Abstract][Full Text]
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]
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]

Other Online Resources

ACC/AHA: guideline for perioperative cardiovascular management for noncardiac surgery
ESC: guidelines on cardiovascular assessment and management of patients undergoing non-cardiac surgery
CCS: guidelines on perioperative cardiac risk assessment and management for patients who undergo noncardiac surgery

Referenced Articles

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Diseases