Local conduction delay causes R-wave amplitude increase in patients with effort angina

Summary Eighty-seven unipolar electrocardiograms distributed over the entire thorax were simultaneously recorded before and after treadmill exercise in 43 patients. Exercise-induced R-wave amplitude change (ΔR) and peak R time (time from the onset of QRS to the peak or R wave), were calculated for each lead. The maximal ΔR of 87 leads was designated as the max ΔR. After exercise, regional delay of peak R time (≥10 msec) on the chest was observed in 13 patients. These patients had significantly higher max ΔR than those without such regional peak R time delay (0.71±0.31mV vs. 0.33±0.20mV, p