IMPROVED DETECTION OF TRANSIENT MYOCARDIAL-ISCHEMIA BY A NEW LEAD COMBINATION - VALUE OF BIPOLAR LEAD NEHB-D FOR HOLTER MONITORING

The investigations of ST-segment changes by Hotter monitoring demonstr ate asymptomatic and symptomatic episodes of myocardial ischemia, whic h may occur during daily activities. One factor, which is of great imp ortance for the detection of silent myocardial ischemia during ambulat ory monitoring, is the combination of the leads. Former studies showed that the analysis of two channels alone may riot adequately detect si lent myocardial ischemia. We therefore used a three-channel ambulatory ECG monitoring system with a new lead combination. The Holter monitor ing results were correlated with the distribution of coronary stenosis detected by coronary angiography. In 54 patients with single coronary vessel disease and ischemic ST-segment depressions during exercise te sting, standard Holter lead combination CM2/CM5 was extended by a bipo lar Nehb D-like lead. Lead combination CM2/CM5 identified 23 patients (43%) with ST-segment depressions (total number of ischemic episodes = 372). Additional Nehb D-like lead identified 30 patients (55%) with S T-segment depressions (total number of ischemic episodes = 1048). The combination of leads CM2/CM5 and Nehb D raised the number of patients with documented ST-segment depressions to 33 of 54 (61%). Lead Nehb D showed the highest sensitivity for the detection of inferior wall isch emia (stenosis of the right coronary artery); nevertheless, this lead may not be regarded as specific for ST-segment alterations only caused by inferior wall ischemia. The correlation of ischemic ST-segment dep ressions during exercise testing (classified as anterior, inferior, or anterior and inferior type-of ischemia) and documented ST-segment cha nges in the different Holter leads underline these results. A control group of 40 healthy volunteers demonstrated the high specifity of this new lead combination. In comparison with the standard lead combinatio n CM2/CM5 for the detection of ST-segment changes, lead combination CM 2/CM5 extended by a bipolar Nehb D lead is more sensitive for the dete ction of ST-segment alterations by Holter monitoring.