[Exercise-induced R wave changes in normals and coronary patients. Computer analysis of CB5 lead (author's transl)].

Changes in R-wave amplitude (delta R) during treadmill test were studied in 84 coronary artery disease (CAD) patients and in 150 normal subjects. The evaluation of ECG recordings (CB5 lead) was carried out by a computer program. At maximal exercise, R-wave decreased by 2.1 +/- 2.8 mm in normal subjects, while in CAD patients mean delta R was significantly lower (0.4 +/- 1.7 mm). When the evaluation of delta R was performed at comparable heart rate and work load values, no significant differences were observed between normals and CAD patients. Using as criterion for a positive test an ischemic ST segment depression greater than or equal to 1.0 mm, the diagnostic sensitivity was 66.7%, while the specificity was 94.0%. When an increase or no change in R-wave was taken as evidence of an abnormal response, sensitivity and specificity values were 57.1% and 65.3% respectively. After a critical review of different parameters able to affect delta R, the difficult physiopathological evaluation and the poor diagnostic reliability of delta R were emphasized. The different heart rate and work load values attained by normals and CAD patients proved to be a further confounding factor in delta R comparison between the two groups.