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Clinical predictors of increased risk
for perioperative cardiac complications
Major
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
Intermediate
Mild angina (Canadian Class I and II)
Prior MI by history or ECG
Compensated or prior CHF
Diabetes Mellitus
Minor
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
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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.
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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.
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