[Diagnostic value of changes in the R-amplitude of the stress ECG compared to the ST-segment depression in patients with significant coronary vessel stenoses]. / Diagnostischer Wert der R-Amplitudenänderungen des Belastungs-EKG im Vergleich zur ST-Streckenverlagerung bei Patienten mit signifikanten Koronargefässstenosen.

Exercise electrocardiograms were registered in 50 patients with significant coronary artery stenosis (lumen narrowing greater than or equal to 70%) and in 20 controls without cardiac disease using automated registration (mapping). All patients had a normal ECG at rest and typical angina. ST-segment depression of more than 0.1 mV 60 ms after the J-point in three adjoining leads and in three consecutive registrations could be shown in 46 of the 50 patients (sensitivity 92%) with coronary artery disease, however in no proband of the control group. The sum of the R-amplitudes in the precardiac leads (sigma R) was calculated before and during maximal exercise and six minutes after. Diminution of R-wave amplitudes during exercise was seen in both groups. Six minutes after exercise initial values had been nearly regained. Differentiation of both groups using R-wave amplitudes after exercise thus was impossible. Even using only leads with ST-segment lowering during exercise, a slight increase of R-amplitudes could be measured in only one case. In all other patients R-wave amplitudes diminished also in the ischaemic area with increasing ST-segment depression. RS-inversion was shifted towards the cardiac apex. Thus an increase of R-wave amplitudes indicating coronary arterial disease does not occur in unipolar chest leads in patients with significant coronary artery stenosis and ST-segment lowering during exercise.