Use of right precordial leads during exercise testing

Do the right precordial leads during exercise testing contribute to detection of coronary artery disease?

BACKGROUND

It is still unknown whether or not the additional right precordial leads (RPL) during exercise testing contribute to detection of coronary artery disease (CAD).

HYPOTHESIS

The aim of this study was to evaluate the RPL during exercise testing for the detection of CAD.

METHODS

The study included 157 consecutive patients (116 men and 41 women, mean age 66 years) suspected of having CAD, who underwent conclusive treadmill exercise testing (heart rate reached at least 85% of the predicted maximum or positive electrocardiogram [ECG] changes were exhibited) and coronary angiography. During exercise testing, the ECG was recorded with the standard 12 leads and 4 RPL (V3R, V4R, V5R, V6R).

RESULTS

Of the 157 patients, 67 had CAD (> 75% stenosis in at least one major coronary artery), and 64 had positive ST changes in the standard ECG leads during exercise testing. Using the conventional 12-lead method, sensitivity and specificity were 76 and 86%, respectively. Only three patients exhibited positive changes in the RPL leads; all had > 0.1 mV ST elevation in one of the RPL leads with > 0.1 mV ST elevation in aVR. Two of these patients had significant right coronary artery lesions and the other had a lesion of the left anterior descending artery which perfused the inferior as well as the anteroseptal area. In the standard 12 leads, one of the patients with an abnormal RPL and a right coronary lesion was negative, while the other two patients were positive. Combining RPL with the conventional 12-lead method, sensitivity and specificity were 78 and 86%, respectively. Therefore, RPL did not improve the accuracy of the exercise ECG.

CONCLUSION

The use of RPL during exercise testing may contribute to the detection of ischemia perfused by the right coronary artery; however, it does not improve the diagnostic accuracy of the exercise test.

Better decisions through science: exercise testing scores

Statistical tools can be used to create scores for assisting in the diagnosis of coronary artery disease and assessing prognosis. General practitioners and internists frequently function as gatekeepers, deciding which patients must be referred to the cardiologist. Therefore, they need to use the basic tools they have available (ie, history, physical examination and the exercise test) in an optimal fashion. Scores derived from multivariable statistical techniques considering clinical and exercise data have demonstrated superior discriminating power compared with diagnosis only using the ST segment response. In addition, by stratifying patients as to probability of disease and prognosis, they provide a more practical management strategy than a response of normal or abnormal. Although computers, as part of information management systems, can calculate complicated equations and derive these scores, physicians are reluctant to trust them. However, when represented as nomograms or simple additive discrete pieces of information, scores are more readily accepted. The scores have been compared with physician judgment and have been found to estimate the presence of coronary disease and prognosis as well as expert cardiologists and often better than nonspecialists. However, the discriminating power of specific variables from the medical history and exercise test remains unclear because of inadequate study design and differences in study populations. Should expired gases be substituted for estimated METs? Should ST/heart rate index be used instead of putting ST depression and heart rate separately into the models? Should right-sided chest leads and heart rate in recovery be considered? There is a need for further evaluation of these easily obtained variables to improve the accuracy of prediction algorithms, especially in women. The portability and reliability of scores must be ensured because access to specialized care must be safeguarded. Assessment of the clinical and exercise test data and application of the newer scores can empower the clinician to assure the cardiac patient access to appropriate and cost-effective cardiologic care.

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 Tl-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 (V(3)R, V(4)R, and V(5)R). 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.