IMPROVED DIAGNOSTIC-ACCURACY WITH THE EVALUATION OF ECG-CHANGES IN EXERCISE-INDUCED SUPRAVENTRICULAR EXTRASYSTOLES

The clinical value of exercise-induced ST segment depression (STx) and R wave amplitude (R(x)) in supraventricular extrasystoles, in the pre ceding sinus beat (STs and R(s) respectively), as well as the combinat ion of the differences between the two of them (STx-s + R(x-s)) was st udied in 96 patients with angiographically documented coronary artery disease (CAD) (group A) - 34 with myocardial infarction (group A(1)) a nd 62 without (group A(2)) - compared to 37 subjects with normal coron ary arteries (group B). ST,, had greater values in group A than in gro up B (0.4 +/- 0.5 vs. -0.2 +/- 0.4 mm; p < 0.0001) as did R(x-s) (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 STx-s had similar values in groups A(1) and A(2) but R(x-s) values were higher in A(1) than in A(2) (P < 0.001). R(x-s), STx-s, and especially their sum (STx-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-vess el 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 (STx-s + R(x-s)) improved sensitivity compar ed 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 dy sfunction it improved sensitivity (from 85 to 91%)with no gain in spec ificity. It is concluded that ST segment depression and R wave amplitu de changes in exercise-induced supraventricular extrasystoles may be o f greater diagnostic significance than in sinus beats, for the detecti on of CAD and left ventricular dysfunction.