Cardiac Risk Stratification

Presenter: Dr S. N. Bhagirath

Moderator: Dr Sharanu Patil

Box 1 Factors to be Considered When Assessing Cardiac Risk

Patient-Related Factors

Age

Chronic diseases (e.g., coronary artery disease, diabetes dellitus, hypertension)

Functional status

Medical therapy

Implantable devices

Previous surgeries

Surgery-Related Factors

Type of surgery (e.g., vascular, endoscopic, abdominal)

Urgency of the operation (e.g., emergent, urgent, elective)

Duration of the operation, possibility of blood loss and fluid shifts

Test-Related Factors

Sensitivity and specificity of a test

Effect on management

Risk Factor Points

Preoperative third heart sound or jugular venous distension indicating active heart failure

11

Myocardial infarction in the past 6 months

10

≥5 premature ventricular complexes/min before surgery

7

Rhythm other than sinus 7

Age >70 years 5

Emergency surgery 4

Significant aortic stenosis 3

Intraperitoneal, intrathoracic, or aortic surgery

3

Markers of poor general medical condition (e.g., renal dysfunction, liver disease, lung disease, electrolyte imbalance)

3

Patients in the lowest risk quartile (0 to 5 points) had less than a 1% risk of postoperative major cardiac complications. In the two quartiles with 6 to 25 points, the major cardiac event risk was 9%, and 22% of the

patients in the highest risk group (≥26 points) had a major perioperative cardiac event.

Goldman Multifactorial Cardiac Risk Index

Eagle’s Cardiac Risk index

One of the limitations of the Goldman criteria was the inability to predict the operative risk for patients undergoing vascular surgery because of the low number of patients with vascular operations included in the study population. This limitation was addressed by Eagle and colleagues

•Q waves on the electrocardiogram (ECG)•History of angina pectoris•History of ventricular ectopy requiring treatment (most specific for predicting events)•Diabetes mellitus requiring therapy other than diet•Age older than 70 years•Thallium redistribution (most sensitive for predicting events)•Ischemic electrocardiographic changes during or after dipyridamole infusion•Combining both the clinical data and thallium imaging was more sensitive and specific than either alone in predicting postoperative complications.

Detsky’s Cardiac Risk Index

A modified cardiac index that included •type of operation, •age, •frequency of premature ventricular contractions (PVCs), •and aortic stenosis •However, heart failure was defined in this study as pulmonary edema determined by chest radiograph or by history of severe respiratory distress and resolution of the symptoms by use of diuretics.

Revised (Lee’s) Cardiac Risk Index• 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, and chest pain secondary to ischemic causes)

• Congestive heart failure• History of cerebrovascular disease• Insulin therapy• Preoperative serum Creatinine level higher than 2 mg/dL

Each of the six risk factors was assigned one point. Patients with none, one, or two risk factor (s) were assigned to RCRI classes I, II, and III, and patients with more than two risk factors were considered Class IV.

The risk associated with each class was 0.4%, 1%, 7%, and 11% for patients in Classes I, II, II, and IV, respectively.

American College of Cardiology Cardiac Risk ClassificationBox 2 Clinical Predictors of Increased Perioperative Cardiovascular Risk*

Major Predictors

Unstable coronary syndromes

•Acute or recent MI† with evidence of important ischemic risk by clinical symptoms or noninvasive study

•Unstable or severe‡ angina (Canadian Class III or IV)

Decompensated heart failure

Significant arrhythmias

•High-grade atrioventricular block

•Symptomatic ventricular arrhythmias in the presence of underlying heart disease

•Supraventricular arrhythmias with uncontrolled ventricular rate

Severe Valvular disease

Intermediate Predictors

Mild angina pectoris (Canadian Class I or II)

Previous MI by history or pathologic Q waves

Compensated or prior heart failure

Diabetes mellitus (especially insulin-dependent type)

Renal insufficiency

Minor Predictors

Advanced age

Abnormal ECG (e.g., left ventricular hypertrophy, left bundle branch block, ST-T abnormalities)

Rhythm other than sinus (e.g., atrial fibrillation)

Low functional capacity (e.g., inability to climb one flight of stairs with a bag of groceries)

History of stroke

Uncontrolled systemic hypertension

ECG, electrocardiogram; MI, myocardial infarction.

Factors Affecting Cardiac Risk

• Coronary Artery Disease• Diabetes• Advanced Age• Hypertension• Valvular Disease• Arrhythmias and Heart Conduction Defects• Permanent Pacemakers and Implantable Cardioverter-Defibrillators• Congestive Heart Failure• Pulmonary Arterial Disease• Congenital Heart Disease• Obesity• Type of Surgery

Box 6 Modified Johns Hopkins Surgical CriteriaGrade IMinimal to Mild Risk Independent of Anesthesia•Breast biopsy

Excludes

•Open exposure of internal body organs

Minimal to Moderately Invasive ProcedureIncludes

•Removal of minor skin or subcutaneous lesions

Excludes

•Repair of vascular or neurologic structures

Potential Blood Loss Less than 500 mLIncludes

•Myringotomy tubes

•Hysteroscopy

•Cystoscopy, vasectomy

•Circumcision

•Fiberoptic bronchoscopy

•Diagnostic laparoscopy dilatation and curettage

•Fallopian tube ligation, arthroscopy

•Inguinal hernia repair

•Laparoscopic lysis of adhesion

•Tonsillectomy, rhinoplasty

Excludes

•Placement of prosthetic devices

•Postoperative monitored care setting

•Open exposure of abdomen, thorax, neck, cranium

•Resection of major body organs

Grade II

Moderately to Significantly Invasive Procedures

Includes

•Thyroidectomy

Excludes

•Open thoracic or intracranial procedure

Potential Blood Loss of 500-1500 mL

Includes

•Hysterectomy

Excludes

•Major vascular repair (e.g., aortofemoral bypass)

Moderate Risk to Patient Independent of Anesthesia

Includes

•Myomectomy

•Cystectomy

•Cholecystectomy, laminectomy

•Hip, knee replacement, nephrectomy

•Major laparoscopic procedures

•Resection, reconstructive surgery of the digestive tract

Excludes

•Planned postoperative monitored care setting (ICU, PACU)

Grade III

Highly Invasive Procedure

•Major orthopedic-spinal reconstruction

Potential Blood Loss More than 1500 mL

•Major reconstruction of the gastrointestinal tract

Major to Critical Risk to Patient Independent of Anesthesia

•Major genitourinary surgery (e.g., radical retropubic prostatectomy)

Usual Postoperative ICU Stay with Invasive Monitoring

•Major vascular repair without postoperative ICU stay

•Cardiothoracic procedure Intracranial procedure

•Major procedure on the oropharynx

•Major vascular, skeletal, neurologic repair

Box 7 Cardiac Risk*

Stratification for Noncardiac Surgical Procedures

High Risk (reported cardiac risk often >5%)

Emergent major operations, particularly in older patients

Aortic and other major vascular surgeries

Peripheral vascular surgery

Anticipated prolonged surgical procedures associated with large fluid shifts, blood loss, or both

Intermediate Risk (reported cardiac risk generally <5%)

Carotid endarterectomy

Head and neck surgery

Intraperitoneal and intrathoracic surgery

Orthopedic surgery

Prostate surgery

Low Risk (reported cardiac risk generally <1%)†

Endoscopic procedures

Superficial procedure

Cataract surgery

Breast surgery

Minimization Of Risk Using Medical Therapy

• Beta Blockers• Lipid-Lowering Agents• a2-Adrenergic Agonists• Preoperative Laboratory Tests for Risk Assessment

Test Cutoff ValueOR/HR of Myocardial ischemia

OR/HR of Death/nonfatal MI

OR/HR of all cardiac complications

BNP >189 pg/ml NA NA 28.78

NT proBNP >270 ng/L 1.49* 1.59* NA

NT proBNP >319 ng/L NA 4† 10.9‡

HbA1c >7% 2.8 3.6 5.6

IGT 5.6-7 mmol/L§ 2.2 2 1.9

DM >7 mmol/L§ 2.6 2.7 3.1

Metabolic Equivalents of Functional Capacity

MET Functional Levels of Exercise

1 Eating, working at a computer, dressing

2 Walking down stairs or in your house, cooking

3 Walking 1-2 blocks4 Raking leaves, gardening5 Climbing 1 flight of stairs, dancing, bicycling6 Playing golf, carrying clubs7 Playing singles tennis8 Rapidly climbing stairs, jogging slowly9 Jumping rope slowly, moderate cycling

10 Swimming quickly, running or jogging briskly

11 Skiing cross country, playing full-court basketball

12 Running rapidly for moderate to long distances

MET, metabolic equivalent of the task. 1 MET = consumption of 3.5 mL O2/min/kg of body weight.

References

• Miller’s Anaesthesia• Johns Hopkins Medical Hospital Website• Goldman and Eagle’s Risk Indices• Stoelting’s Co-existing diseases• Morgan’s Clinical Anaesthesiology• Clinical Anaesthesiology by Paul G. Barash• WebMD• Springer Online