American College of Cardiology

GIBBONS ET AL., 2002 GUIDELINE UPDATE FOR EXERCISE TESTING
Circulation 2002;106:1883-1892

ACC/AHA 2002 Guideline Update for Exercise Testing—Summary Article

A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to Update the 1997 Excercise Testing Guidelines)

Modification I

The text in the 1997 guidelines that appeared under the major heading "Diagnosis" and the subheading "Influence of Other Factors on Test Performance" has been extensively reorganized. This began on page 272 (second column) of the original guidelines. New material regarding ST-heart rate and adjustment changes during and after exercise is reproduced below. New material on atrial repolarization and right chest leads appears in the full-text guidelines on the Internet.

ST-Heart Rate Adjustment
Several methods of heart rate adjustment have been proposed to increase the diagnostic accuracy of the exercise ECG. The maximal slope of the ST segment relative to heart rate is derived either manually¹ or by computer.² A second technique, termed the ST/HR index, divides the difference between ST depression at peak exercise by the exercise-induced increase in heart rate.^3,4 ST/HR adjustment has been the subject of several reviews since the last publication of these guidelines.^5,6 The major studies that used this approach for diagnostic testing include Morise's report⁷ of 1358 individuals undergoing exercise testing (only 152 with catheterization data) and the report by Okin et al⁸ considering heart rate reserve (238 controls and 337 patients with coronary disease).

Viik et al considered the maximum value of the ST-segment depression/heart rate (ST/HR) hysteresis over a different number of leads for the detection of coronary artery disease (CAD).⁹ The study population consisted of 127 patients with coronary disease and 220 patients with a low likelihood of the disease referred for an exercise test. Neither the study by Okin et al or that by Viik et al considered consecutive patients with chest pain, and both had limited challenge. Because healthy patients have relatively high heart rates and sick patients have low heart rates, which leads to a lower ST/HR index in normals and a higher index in sicker patients, the enrollment of relatively healthy patients in these studies presents a limited challenge to the ST/HR index. Likewise, the Morise study⁷ had a small number of patients who underwent angiography. The only study with neither of these limitations was QUEXTA.¹⁰ This large multicenter study followed a protocol to reduce workup bias and was analyzed by independent statisticians. The ST/HR slope or index was not found to be more accurate than simple measurement of the ST segment. Although some studies in asymptomatic (and therefore very low likelihood) individuals have demonstrated additional prognostic value with ST/HR adjustment, these data are not directly applicable to the issue of diagnosis in symptomatic patients.^11,12 Nevertheless, one could take the perspective that the ST/HR approach in symptomatic patients has at least equivalent accuracy to the standard approach. Although not yet validated, there are situations in which the ST/HR approach could prove useful, such as in rendering a judgment concerning certain borderline or equivocal ST responses, eg, ST-segment depression associated with a very high exercise heart rate.

In asymptomatic patients, in MRFIT, significant concentration of cardiac risk was associated with an abnormal ST/HR index but not with abnormal standard exercise test criteria as judged by computer interpretation.12 Compared with patients in the usual care group, cardiac events were reduced in the risk factor modification group when the exercise test was positive according to the ST/HR index.¹³

© 2002 by the American College of Cardiology Foundation and the American Heart Association, Inc.