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The Electrocardiographic Exercise Test in a Population with Reduced Workup Bias: Diagnostic Performance, Computerized Interpretation, and Multivariable Prediction

Victor F. Froelicher, MD; Kenneth G. Lehmann, MD; Ronald Thomas, PhD; Steven Goldman, MD; Douglas Morrison, MD; Robert Edson, MS; Philip Lavori, PhD; Jonathan Myers, PhD; Charles Dennis, MD; Ralph Shabetai, MD; Dat Do, BA; Jeffrey Froning, MS, The Veterans Affairs Cooperative Study in Health Services #016 (QUEXTA) Study Group*
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Copyright ©2004 by the American College of Physicians

Ann Intern Med. 1998;128(12_Part_1):965-974. doi:10.7326/0003-4819-128-12_Part_1-199806150-00001
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Background: Empirical scores, computerized ST-segment measurements, and equations have been proposed as tools for improving the diagnostic performance of the exercise test.

Objective: To compare the diagnostic utility of these scores, measurements, and equations with that of visual ST-segment measurements in patients with reduced workup bias.

Design: Prospective analysis.

Setting: 12 university-affiliated Veterans Affairs Medical Centers.

Patients: 814 consecutive patients who presented with angina pectoris and agreed to undergo both exercise testing and coronary angiography.

Measurements: Digital electrocardiographic recorders and angiographic calipers were used for testing at each site, and test results were sent to core laboratories.

Results: Although 25% of patients had previously had testing, workup bias was reduced, as shown by comparison with a pilot study group. This reduction resulted in a sensitivity of 45% and a specificity of 85% for visual analysis. Computerized measurements and visual analysis had similar diagnostic power. Equations incorporating nonelectrocardiographic variables and either visual or computerized ST-segment measurement had similar discrimination and were superior to single ST-segment measurements. These equations correctly classified 5 more patients of every 100 tested (areas under the receiver-operating characteristic curve, 0.80 for equations and 0.68 for visual analysis; P < 0.001) in this population with a 50% prevalence of disease.

Conclusions: Standard exercise tests had lower sensitivity but higher specificity in this population with reduced work-up bias than in previous studies. Computerized ST-segment measurements were similar to visual ST-segment measurements made by cardiologists. Considering more than ST-segment measurements can enhance the diagnostic power of the exercise test.

*For members of the Veterans Affairs Cooperative Study in Health Services #016 (QUEXTA) Study Group, see Appendix 2.


Grahic Jump Location
Figure 1.
Receiver-operating characteristic curves comparing the diagnostic capacity of standard visual ST-segment analysis with that of the major logistic regression equations.Table 3Table 4

The vertical line is at the specificity obtained with 1 mm of visual ST-segment depression (85%). The Equation from step 4 ( ) , that included clinical, hemodynamic, visual ST-segment, and computerized measurements is similar to the Equation fromstep 3b, and both equations have better discrimination than single electrocardiographic measurements do.

Grahic Jump Location
Grahic Jump Location
Figure 2.
Receiver-operating characteristic curves comparing the diagnostic capacity of standard visual ST-segment analysis with that of several computerized measurements.

The computer measurements are similar but not superior to visual analysis. MAX EX = maximal exercise; STO = beginning of ST segment; ST60 = ST amplitude 60 milliseconds after QRS end.

Grahic Jump Location




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