The Influence of R-Wave Amplitude on the Degree of ST-Segment Depression in Exercise Electrocardiography in the Individual Patient

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Abstract
Many factors have been found to influence the magnitude of ST-segment depression in the exercise electrocardiogram. We investigated whether R-wave amplitude is a significant factor. We studied the exercise electrocardiogram of 20 patients with angiographically documented coronary artery disease, including ≥ 70% stenosis of the left anterior descending artery, who had an ischemic response to exercise but no previous anterior myocardial infarction. Precordial leads V1-6 were taken into account. When all 120 leads were measured, those with ST-segment depression ≥ 2.0mm at peak exercise had a mean resting R-wave amplitude of 19.03±5.81mm; those with ST-segment depression 2.0-1.0mm, R 11.42±5.99mm; and those with ST-segment depression < 1.0mm, R 5.9±5.21mm (p < 0.001 between groups). When the R-wave amplitude was correlated with the ST-segment depression in each precordial lead, the correlation was 1.0. In leads V1-6, when 67 tracings with ST-segment depression > 0.5mm were measured, the correlation was 0.537 (p < 0.001). In each precordial lead the t values of R-wave differences correlated very strongly (r < 0.883) with the differences in ST-segment depression. We conclude that precordial R-wave amplitude significantly influences the magnitude of ST-segment depression.