The relationship between ST segment deviation projected to the front of the chest during exercise and simultaneous Holter monitoring

Simultaneous two-channel Holter monitoring, with a direct recordingsystem, and maximal exercise testing with a 12-lead precordialelectrocardiographic mapping system were performed in 50 patientswith chest pain (41 with documented coronary artery disease,9 without). The exploring Holter leads were placed to correspondto CM5 and an aVF-like lead. In 36 patients, ST segment changeswere found with both Holter and the 12-lead precordial electrocardiogram,while in 12 patients no ischaemic changes were detected by eithermethod. Thus the results of the two methods concurred in 48of 50 patient (96%). The magnitude of the ischaemic change wassimilar in 24 of 36 patients (67%), while the Holter systemunderestimated the ischaemic change by 0.5–2.0 mm in 12patients. When the maximal ST segment deviation in V5 was comparedwith CM5, the deviations with both systems were identical inall but one patient in whom a difference of 0.5 mm was found.The use of a Holter lead resembling aVF identified maximal STsegment change on only one occasion, and in only four patientswas an ST segment change of 1 mm noted. In conclusion, ambulatory monitoring utilizing only CM5 seemsto detect most episodes with ST segment changes, but the useof a 12-lead precordial mapping system during exercise testingmay expand the possibility of defining the optimal sites forthe exploring Holter leads to detect maximal ST segment change.