Abstract
To know the relationship between positive ventricular late potentials (LP) and occurrence of ventricular tachycardia (VT), signal-averaged electrocardiogram (SAECG) was recorded in 214 patients with myocardial infarction (MI). According to the time course of SAECG recording after the onset of MI, the subjects were divided into three groups; acute MI (AMI) group (onset-2nd week, n=148), recent MI (RMI) group (3rd-6th week, n=19) and old MI (OMI) group (7th week or later, n=47). The incidence of positive LP in each group was 22.3%, 36.8% and 12.8%, respectively. VT was observed in 51.5% (AMI), 71.4% (RMI) and 83.3% (OMI) in LP positive patients, and these proportions were significantly higher than those (25.2%, 0% and 9.8%) in LP negative patients. Sensitivity, specificity and predictive accuracy of positive LP to predict occurrence of VT were 37.0%, 84.3% and 69.7% in AMI, 100%, 85.7% and 89.5% in RMI and 55.6%, 97.4% and 89.5% in OMI, respectively. Incidence of positive LP in the patients with inferior infarction (23.9%) or with combination of inferior and anterior infarction (60.0%) were significantly higher than those in patients with anterior infarction alone (13.9%). Significantly higher peak-CPK value (4333±2580 IU/L) in the patients with positive LP compared to those with negative LP (2438±2023 IU/L) suggests that patients with positive LP have an infarction of larger size. In conclusion, non-invasive LP detection using signal averaging technique was useful in prediction of occurrence of VT in patients with MI in any phase.
