Use of additional electrocardiograph leads in low-risk patients undergoing exercise treadmill testing

Studies have shown that the addition of right precordial and left posterior leads to the standard 12-lead electrocardiogram (ECG) can significantly improve the sensitivity of exercise treadmill testing (ETT) for the diagnosis of myocardial ischemia.

The objective of this study was to determine the value of adding 2 rightsided (RV3, RV4) and 2 left posterior (V8, V9) auxiliary leads to enhance detection of myocardial ischemia in patients with chest pain identified as low risk.

The authors conducted a prospective study of all patients undergoing ETT as part of their management in a chest pain evaluation unit (CPEU) at a tertiary medical center from November 1999 to November 2001. Patients were considered low risk for acute coronary syndrome based on the clinical presentation to the CPEU, absence of ischemia on resting ECG, and negative initial cardiac markers. Diagnosis of coronary artery disease (CAD) was based on confirmatory testing, which included coronary angiography, myocardial stress scintigraphy, exercise echocardiography, or 30-day follow-up period.

The study cohort comprised 705 patients who underwent 16-lead ETT. Of these, 70 (10%) had positive ETT and CAD was confirmed by further evaluation in 26. ECG changes positive for ischemia were demonstrated on the standard 12-lead exercise ECG in 68 patients. An additional 2 patients had positive ECG alterations only in the 4 auxiliary leads on the 16-lead ECG. There was no significant difference in the sensitivity or positive predictive value between the 12- and 16-lead exercise ECG.

Electrocardiographic changes in auxiliary leads did not change the diagnostic use of the ETT and therefore may provide only a minimal contribution to the assessment of the low-risk CPEU population.