Comparison of continuous vectorcardiography and continuous 12-lead electrocardiography of patients with unstable coronary artery disease: do they identify the same population?

BACKGROUND: Continuous vectorcardiography (cVCG) and continuous 12-lead electrocardiography (c12ECG) are important tools for assessing patients with unstable coronary artery disease. OBJECTIVE: To compare the incidences of ischemia detected by the two methods, and examine whether the patients identified belonged to the same population, with respect to various clinical variables. METHODS: Within a randomized prospective trial (FRISC II) including patients with unstable coronary artery disease, ST-segment monitoring was performed either by cVCG or by c12ECG for 24 h after admission for 1016 patients. RESULTS: cVCG and c12ECG were performed for 730 and 286 patients, respectively. Transient ischemic episodes in 253 (34.7%) patients were detected by cVCG and such episodes were detected in 91 (31.8%) patients by c12EGG. When patients in whom transient ischemic episodes had been detected by cVCG and c12ECG were compared, the groups were similar with respect to baseline characteristics, signs of myocardial damage (67.5 versus 70.5%), occurrence of exercise-induced ischemia (59.0 versus 60.0%), and presence of severe coronary lesions (57.0 versus 51.3%). CONCLUSIONS: Results of this study suggest that these two methods identify the same high-risk population, and that these patients can be considered one group when results obtained using either system are analyzed in multicenter studies. This also implies that results concerning the occurrence of episodes of resting ischemia obtained using one system may also be applicable for the other.