Coronary Artery Disease: Evaluation by the Multistage Treadmill Exercise Test and Right Atrial Pacing

¹ Division of Cardiology, Department of Medicine, Hahnemann Medical College and Hospital, Philadelphia; Department of Physiology and Medicine, The University of Texas Medical School at San Antonio, San Antonio
² Department of Physiology and Medicine, The University of Texas Medical School at San Antonio, San Antonio

Atrial pacing and treadmill exercise were performed by 28 patients to determine the value of each test in the clinical and functional evaluation of the patient with coronary artery disease (CAD). The functional aerobic impairment (FAI) in 20 patients was 48 percent (eight patients with unstable angina paced but not exercised) and the pacing ventricular function curve (VFC) was abnormal in 13 of these 20. Five patients with severe FAI (pain limited) had a normal pacing VFC. Although the FAI was greater the more extensive the CAD, no such correlation existed between the pacing VFC and the number of diseased coronary vessels. Exercise testing does not necessarily indicate the functional performance of the left ventricle since the VO₂ max is frequently pain limited. Atrial pacing, although less sensitive, permits a VFC determination, even in poorly motivated and nonambulatory patients, and combined studies will indicate the patient's clinical, as well as myocardial status.