100 QUESTIONS IN CARDIOLOGY

101 Which factors predict cardiac risk from

general surgery and what is the magnitude of the

risks associated with each factor?

Matthew Barnard

Mangano and colleagues reported an in-hospital adverse cardiac

event rate of 17.5% among patients undergoing major non-

cardiac surgery.^1 Four factors require consideration:

11 Clinical predictors

22 Functional status

33 Surgical magnitude

44 Results of non-invasive investigations.

Clinical risk factors have been integrated into clinical risk

scores, of which the best known are the Goldman, Detsky and

Eagle scores (Table 101.1).^2 Detsky and colleagues have reported

the likelihood of post-testing adverse cardiac events for these

scores (Table 101.2).^3 The American Heart Association has

classified clinical risk factors into three categories (Table 101.3),

based on the conclusions of a consensus conference.^4 This index

retains the greatest clinical utility.

Functional capacity determines the need for non-invasive

testing in the presence of intermediate or minor clinical

predictors. Daily activities can be scored according to estimated

energy expenditure (Table 101.4). The magnitude of the surgical

procedure also influences risk (Table 101.5). High surgical risk

combined with intermediate clinical risk factors or minor clinical

risk factors plus low functional capacity dictate the need for non-

invasive testing.

It is vital to understand that the positive and negative

predictive value of non-invasive tests (e.g. thallium scans and

dobutamine stress echocardiography) depend critically on the

underlying prevalence of cardiac disease in the population. Very

low or very high levels of ischaemic heart disease diminish the

value of these tests, which are most useful in groups with inter-

mediate levels of disease.^5