Cardiac Risk Assessment Before Noncardiac Surgery

Clinical Predictors of Perioperative Cardiac complications
Mortality Risk with Perioperative MI
Functional Capacity
Surgery-specific Cardiac Risk
General Considerations


Clinical predictors of increased risk
for perioperative cardiac complications

Unstable or severe angina (Canadian Class III or IV)
Recent MI (>7 days but <30 days) with evidence of important ischemic risk by clinical symptoms or noninvasive testing
Decompensated CHF
Symptomatic arrhythmias, including high-grade AVB
Symptomatic ventricular arrhythmia in the presence of underlying heart disease, and supraventricular arrhythmias with uncontrolled ventricular rate
Mild angina (Canadian Class I and II)
Prior MI by history or ECG
Compensated or prior CHF
Diabetes Mellitus
Old age
Abnormal ECG (LVH, LBBB, ST-T abnormalities
Rhythm other than sinus (e.g., atrial fibrillation)
Low functional capacity
History of stroke
Uncontrolled systemic hypertension

Mortality risk with perioperative MI

No prior MI    0.1 to 0.6 %
Previous MI  2.8 - 7 %
MI in past 3 months * 37 %
MI 3-6 months prior to surgery 16 %
MI 6 months or more prior to surgery 4% 

*10-15% with more recent data
Perioperative MI is associated with 26% to 70% mortality rate; most occurring in the first three days after surgery, with peak incidence in day 2.

Functional Capacity

Functional capacity reliably predicts future cardiac events and should be assessed by history preoperatively in all patients. Functional capacity is usually expressed as metabolic equivalent (MET) levels, one MET being equivalent to the oxygen consumption (VO2) of a 70 kg. 40 yr-old man in a resting state (3.5 mL/kg/min).

Excellent (activities requiring >7 METS)
Carry 24 lb up eight steps
Walking 5 MPH; carry objects that weigh 80 lbs
Outdoor work: shovel snow, spade soil
Recreation: ski, basketball, squash, handball, jog
Moderate (activities requiring 4-7 METS)
Have sexual intercourse without stopping
Walk at 4 MPH on level ground
Outdoor work: garden, rake, weed
Recreation: roller skate, dance
Poor (activities requiring <4 METS)
Shower/dress without stopping, strip and make bed, dusting
Walk at 2.5 mph on level ground
Outdoor work: clean windows
Recreation: golf, bowling

Perioperative and long-term cardiac risks are increased in patients with poor functional capacity. Noninvasive cardiac risk assessment should be considered in these patients before elective noncardiac surgery, depending on the type of surgery and the presence of clinical risk predictors discussed above.
   Patients with moderate or excellent functional capacity and minor clinical risk factors can generally proceed to elective surgery without undergoing further cardiac workup. The same is true for patients with intermediate risk factors and excellent functional capacity who are scheduled for low- or intermediate-risk surgery. However, patients with intermediate clinical risk factors who are facing high-risk surgery should be considered for preoperative noninvasive cardiac risk evaluation.

Surgery-specific cardiac risk
High (reported cardiac risk >5%)
Emergent major operation (particular in elderly)
Aortic and other major vascular
Peripheral vascular
Anticipated prolonged surgical procedures associated
with large fluid shifts and/or blood loss
Intermediate (reported cardiac risk <5%)
Carotid endarterectomy
Head and Neck
Intraperitoneal and intrathoracic
Low (reported cardiac risk <1%)
Endoscopic procedures
Superficial procedures

General Considerations: Risks & Evaluations

Patients who have undergone CABG surgery in the past five years or PTCA (percutaneous transluminal coronary angioplasty) in the past six months to five years, and who are functionally active and free of clinical evidence of ischemia, may proceed to surgery without further cardiac testing. The likelihood of a perioperative cardiac event in these patients are extremely low.

In general, patients who have been evaluated in the past two years with invasive and noninvasive techniques and whose findings are favorable need no further cardiac workup if they've been free of cardiac symptoms since the test. Patients with changing symptoms or signs of ischemia should undergo further evaluation.

If a patient has one of the major clinical predictors and is scheduled for elective surgery, it is best to postpone the operation until the cardiac problem is clarified and treated. A referral for coronary angiography may be necessary.

Patients with one or more intermediate clinical predictors of cardiac risk and moderate or excellent functional capacity can generally undergo low- or intermediate-risk surgery with low perioperative event rates. But poor functional capacity or a combination of high-risk surgery and moderate functional capacity in a patient with intermediate clinical predictors of cardiac risk (especially if two or more are present) mandates further noninvasive cardiac testing.

Generally, patients with minor or no clinical predictors or risk and moderate of excellent functional capacity can safely undergo any type of noncardiac surgery.


Assessing Cardiac Risk Before Noncardiac Surgery
Internal Medicine/January 1998 / Vol. 19, No. 1
Rajendra Metha, MD, and Kim A. Eagle, MD