Background: The limitations of exercise electrocardiography in the detection of coronary artery disease includes low sensitivity, especially in isolated right coronary artery (RCA) disease. Recent studies postulated the addition of right precordial leads to the standard exercise ECG (ExT) recording for better detection of right ventricular ischemia.
Purpose: We tested the hypothesis that the replacement of the standard first precordial lead (V1) with a fourth right chest lead (V4R) can improve the diagnostic accuracy of ExT.
Materials and methods: We studied 100 patients (78 men and 22 women, aged 55 +/- 9 years (31-71)) who underwent treadmill ExT (Bruce protocol) and coronary angiography. 52 patients had the V4R lead (Group V4R) instead of V1. The control group (Group V1) included 48 patients with the standard 12-lead ECG. Hemodynamically significant lesions were defined as stenosis > = 50% in left main coronary artery or > = 70% in other arteries.
Results: 76 out of 100 patients had significant coronary lesions on the arteriogram, 81% in Group V4R and 71% in Group V1. Overall sensitivity (71% Group V4R vs 79% Group V1), specificity (40% Group V4R vs 21% Group V1) and accuracy (65% Group V4R vs 63% Group V1) of ExT for detection of significant coronary artery disease was similar in both groups. There was also no statistically significant difference in the ability to define an inferior or right ventricle vs. anterolateral ischemia between both groups. Only 5 out of 32 (16%) patients with significant lesions in RCA revealed ST changes in V4R.
Conclusions: In our study, the application of V4R instead of V1 did not significantly change the accuracy of ExT. Typical ECG signs of ischemia in V4R have high specificity, but low sensitivity for RCA disease. Thus, modification of the standard 12-lead scheme cannot be advocated for routine ExT, however although the use of a wider electrocardiographic window (e.g. V3R-V5R) might be more successful for recording right ventricular ischemia.