Use of functional tests before angiography in patients with normal coronary arteries

Functional tests provide diagnostic and prognostic information in patients with suspected coronary disease and are recommended in investigating and guiding management of these patients. There is little data on their utilization, especially in patients with low to intermediate pre-test probability of disease.

From 6053 consecutive patients who underwent 6830 coronary angiograms for suspected coronary disease, 758 patients were subsequently found to have normal coronary arteries. Clinical data, functional tests performed prior to angiography and referring physicians were analyzed.

The 758 patients had mean pre-test probability of disease of 42+/-30%. Only 483 patients had undergone functional tests before angiography. There were no differences in gender, age, and pre-test probability between patients who underwent functional tests and those who did not. Three hundred thirteen patients underwent angiography as inpatients while 445 were day-only patients. Inpatients were less likely to have undergone functional tests prior to angiography. Inpatient status was the only independent predictor of not undergoing functional tests (OR 5.9, p<0.001). Functional tests revealed inducible ischaemia in only 241 of the 483 patients. Patients referred by cardiologists were more likely to have undergone functional tests compared with those referred by other physicians. Procedural cardiologists and non-procedural cardiologists had similar rate of use of functional tests.

In our patients with normal coronary arteries, utilization of functional tests was low, particularly for inpatients. A significant proportion proceeded to angiography despite negative functional tests. Referrer characteristics and inpatient status, rather than pre-test probability, appeared to have greater impact on utilization of functional tests.