Diagnosis of Obstructive Coronary Disease by Maximal Exercise and Atrial Pacing

The reliability of graded maximal exercise treadmill testing and right atrial pacing in diagnosing significant obstructive coronary artery disease was evaluated in 74 consecutive patients referred to a cardiac unit with chest pain consistent with angina pectoris. The results of maximal exercise testing and right atrial pacing, with regard to the presence or absence of the patient's characteristic chest pain or discomfort and ischemic ST segment depression, were compared with the findings determined by selective coronary arteriography. Ischemic ST segment depression was defined as a downward displacement of one full mm or more of a horizontal or downward sagging ST segment. Forty-nine of the 74 patients studied were found to have significant coronary arteriographic obstruction, i.e., greater than 75% obstruction of one major coronary artery. The occurrence of the patient's characteristic chest pain or discomfort during maximal exercise testing or right atrial pacing is an excellent indicator of the presence of obstructive coronary artery disease, since all of the 41 patients developing their characteristic pain on maximal exercise testing had coronary arteriograms positive for obstructive coronary disease (no false positives), and 46 of 47 patients with characteristic chest pain on right atrial pacing had selective coronary arteriograms positive for obstructive coronary disease. When present, one mm ST depression during maximal exercise treadmill testing also reliably indicates arteriographic obstructive coronary disease (26 of 27 patients). However, the presence or absence of ischemic ST depression during right atrial pacing is a particularly unreliable indication of the presence or absence of arteriographic obstructive coronary disease: 15 of 25 false positive tests, and 13 of 49 false negative tests.