Failure of right precordial electrocardiography during stress testing to identify coronary artery disease

Background. It has been reported that the use of right precordial leads results in the same diagnostic accuracy as thallium-201 exercise scintigraphy for the detection of coronary artery disease (CAD). The aim of this study was to evaluate the utility of right precordial leads in the detection of CAD. Methods and Results. We evaluated 900 consecutive patients (514 men, 386 women) ranging in age from 39 to 84 years (mean ± SD, 64 ± 11 years). Seven hundred forty patients underwent treadmill exercise testing, and 160 underwent pharmacologic stress testing for the diagnosis of chest pain or dyspnea. All received either TI-201 or technetium-99m sestamibi during stress. During stress testing, the ECG was recorded every minute with 12 limb and left precordial leads and 3 right precordial leads (V₃R, V₄R, and V₅R). The electrocardiogram was considered positive when the ST segment was either elevated or depressed by at least 0.1 mV at 80 ms after the J point, and results were also compared with single photon emission computed tomography myocardial perfusion imaging results. Of the 900 patients, 158 had significant positive changes in the limb or left precordial leads. Only 4 patients had positive changes in the right precordial leads (Fisher exact test, P<.001). Of the patients who had positive electrocardiographic changes, 95 (60%) had abnormal myocardial perfusion scans, with 91 in patients with normal right precordial leads. All 4 patients with ischemic changes in the right precordial leads had abnormal scans, but the left leads were also positive. Three hundred seventy-three of 900 patients (41%) had abnormal scans with no electrocardiographic evidence of ischemia. Conclusions. Our experience is far different than that published and suggests that the use of right precordial leads during stress testing fails to provide the same diagnostic accuracy as either the standard left-sided electrocardiography or myocardial perfusion imaging for the detection of CAD.