Diagnostic and Prognostic Value of Lead aVR During Exercise Testing in Patients Suspected of Having Myocardial Ischemia

We aimed to assess the diagnostic and prognostic value of ST-segment deviation in aVR, a lead often ignored in clinical practice, during exercise testing and to compare it to the most widely used criterion of ST-segment depression in V₅. We enrolled 1,596 patients with suspected myocardial ischemia referred for nuclear perfusion imaging undergoing bicycle stress testing. ST-segment amplitudes in leads aVR and V₅ were automatically measured. The presence of inducible myocardial ischemia was the diagnostic end point and adjudicated based on nuclear perfusion imaging and coronary angiography. Major adverse cardiac events (MACE) during 2 years of follow-up including death, acute myocardial infarction, and coronary revascularization were the prognostic end point. Exercise-induced myocardial ischemia was detected in 470 patients (29%). Median ST amplitudes for leads aVR and V₅ differed significantly among patients with and without ischemia (p <0.01). The diagnostic accuracy of ST changes for myocardial ischemia as quantified by the area under the receiver operating characteristic curve was highest 2 minutes into recovery and similar in aVR and V₅ (0.62, 95% confidence interval CI 0.60 to 0.65 vs 0.60, 95% confidence interval 0.58 to 0.63, p = 0.08 for comparison). In multivariate analysis, ST changes in lead aVR, but not lead V₅, contributed independent diagnostic information on top of clinical parameters and manual electrocardiographic interpretation. Within 2 years of follow-up, MACE occurred in 33% of patients with ST elevations in aVR and in 16% without (p <0.001). In conclusion, ST elevation in lead aVR during exercise testing indicates inducible myocardial ischemia independently of ST depressions in lead V₅ and clinical factors and also predicts MACE during follow-up.

Diagnostic value of ST-segment deviations during cardiac exercise stress testing: Systematic comparison of different ECG leads and time-points

BACKGROUND

Exercise ECG stress testing is the most widely available method for evaluation of patients with suspected myocardial ischemia. Its major limitation is the relatively poor accuracy of ST-segment changes regarding ischemia detection. Little is known about the optimal method to assess ST-deviations.

METHODS

A total of 1558 consecutive patients undergoing bicycle exercise stress myocardial perfusion imaging (MPI) were enrolled. Presence of inducible myocardial ischemia was adjudicated using MPI results. The diagnostic value of ST-deviations for detection of exercise-induced myocardial ischemia was systematically analyzed 1) for each individual lead, 2) at three different intervals after the J-point (J+40ms, J+60ms, J+80ms), and 3) at different time points during the test (baseline, maximal workload, 2min into recovery).

RESULTS

Exercise-induced ischemia was detected in 481 (31%) patients. The diagnostic accuracy of ST-deviations was highest at +80ms after the J-point, and at 2min into recovery. At this point, ST-amplitude showed an AUC of 0.63 (95% CI 0.59-0.66) for the best-performing lead I. The combination of ST-amplitude and ST-slope in lead I did not increase the AUC. Lead I reached a sensitivity of 37% and a specificity of 83%, with similar sensitivity to manual ECG analysis (34%, p=0.31) but lower specificity (90%, p<0.001).

CONCLUSION

When using ECG stress testing for evaluation of patients with suspected myocardial ischemia, the diagnostic accuracy of ST-deviations is highest when evaluated at +80ms after the J-point, and at 2min into recovery.