Improved Diagnostic Accuracy with the Evaluation of ECG Changes in Exercise-Induced Supraventricular Extrasystoles

Abstract

The clinical value of exercise-induced ST segment depression (ST(x)) and R wave amplitude (R(x)) in supraventricular extrasystoles, in the preceding sinus beat (ST(s) and Rs respectively), as well as the combination of the differences between the two of them (ST(x-s) + R(x-s)) was studied in 96 patients with angiographically documented coronary artery disease (CAD) (group A) - 34 with myocardial infarction (group Ai) and 62 without (group A(2)) - compared to 37 subjects with normal coronary arteries (group B). ST(x-s) had greater values in group A than in group B (0.4 ± 0.5 vs. -0.2 ± 0.4 mm; p < 0.0001) as did R (0.6 ± 0.5 vs.-1.1 ± 0.8 mm; p< 0.0001) and their combination (1.0 ± 0.7 vs.-1.3 ± 1.0 mm; p < 0.0001), while ST(x-s) had similar values in groups Ai and A(2) but R(x-s) values were higher in Ai than in A(2) (p< 0.001). R(x-s), ST(x-s) and especially their sum (ST(x-s) + R(x-s)) value was directly related to the number of vessel disease (0.7 ± 0.5 mm for 1-, 1.1 ± 0.7 mm for 2-, and 1.4 ± 0.7 mm for 3-vessel disease; p < 0.0001), while it was significantly higher in patients with left ventricular dysfunction (-0.01 ± 1.2 vs. 1.5 ± 0.8 mm; p< 0.0001). The value of (ST(x-s) + R(x-s)) improved sensitivity compared to the sinus signs (from 66 to 87%) as well as specificity (from 82 to 95%) for CAD detection, while for detection of left ventricular dysfunction it improved sensitivity (from 85 to 91%) with no gain in specificity. It is concluded that ST segment depression and R wave amplitude changes in exercise-induced supraventricular extrasystoles may be of greater diagnostic significance than in sinus beats, for the detection of CAD and left ventricular dysfunction.