CURRICULUM IN CARDIOLOGY EWuation of coronary artery dieease in the patient unable to exercise: Alternatives to exercise stress testing Henry G. Stratmann, MD, and Harold L. Kennedy, MD, MPH. St. Louis, MO. Exercise stress testing is a well-established method for evaluating the presence of coronary artery dis- ease (CAD).lm5 In patients with known CAD the test can be used to determine its functional and prognos- tic significance, or to assess the need for and efficacy of therapy with antianginal medications, coronary artery bypass surgery, or coronary angioplasty.‘-l6 The value of the test may be increased by the addition of thallium-201 scintigraphy,17s l8 radionu- elide ventriculography,1g*20 two-dimensional echo- cardiography,21* 22 or Doppler echocardiography.23s 24 Although coronary angiography is superior to exer- cise stress testing for detecting the presence of CAD, it also has certain disadvantages. Compared to exercise testing, angiography is more expensive and technically demanding and, because it is invasive, is associated with a greater morbidity and mortali- ty.le5, 25, 26 Also, angiography gives only anatomic information, and thus its ability to assess the func- tional significance of CAD in an individual patient may be limited.3-5v 27* 28 Conversely, although limited in its ability to provide information concerning coronary anatomy,3-5 exercise testing is quite useful for evaluating the physiologic significance of CAD. Thus the two tests complement each other, and in many patients both are necessary to assess the significance of CAD and to make clinical decisions regarding therapy. However, some patients with clinical indications for exercise stress testing are unable to perform adequate levels of exercise because of noncardiac limitations (Table I). A variety of techniques have been proposed as alternatives to exercise stress testing in such patients (Table II). In the following review we describe each of these methods and From the Department of Cardiology, St. Louis Veterans Administration Medical Center and St. Louis University. Received for publication Dec. 5, 1988; accepted Jan. 15, 1989. Reprint requests: Henry Stratmann, MD, St. Louis University School of Medicine, Department of Cardiology, St. Louis Veterans Administration Medical Center, St. Louis, MO 63125. 1344 Table I. Physical factors that may limit or preclude the use of exercise stress testing for evaluating CAD Lower extremity problems Arthritis or other joint disease Fracture Amputation Peripheral vascular disease Neuromuscular weakness peasons for decreased ability to exercise Obesity Chronic obstructive pulmonary disease Impaired left ventricular function Advanced age Deconditioning or generalized weakness Recent surgery Miscellaneous Lack of motivation Inability to cooperate with test compare them both to each other and to exercise stress testing. ATRIAL PACING Technique. Clinical use of atria1 pacing to assess CAD was first described by Sowton et a1.2g in 1967. Since then pacing-induced tachycardia has been used to evaluate both the presence of CAD30-38 and the results of various therapeutic interventions in patients with known CAD.30,3g-43 Pacing may be performed by means of several different teehniques. In the usual method a bipolar 4F to 8F pacing catheter is introduced percutaneously into an ante- cubital or femoral vein.32B42-M If coronary sinus blood samples are to be drawn for determination of lactate concentration, a catheter with an end or side hole is used. The catheter is advanced under fluoroscopic direction into the right atrium or coronary si- nus.3g-43s45,46 If fluoroscopy is not available the distal electrode is connected to the V lead of an ECG machine, and the catheter is advanced until location within the right atrium is confirmed by recording large atria1 electrograms. The catheter is then con-