Dispersion of ventricular repolarization in hypertrophic cardiomyopathy.

On an averaged QRS-T cycle from a 15-lead record (12-lead electrocardiogram + XYZ leads) and through interactive editing, four electrocardiographic indices of the dispersion of ventricular repolarization (DVR) are automatically computed and represent the maximal interlead difference of QT and JTend and QT and JTapex. The values of these indices were then examined in three clinical groups matched for age and sex: normal subjects (control), patients with left ventricular hypertrophy (LVH group), and patients with hypertrophic cardiomyopathy (HCM group) without ventricular arrhythmias and without interacting drugs. The mean values of all four DVR indices were significantly increased in the HCM group compared with the control group and the LVH group of another origin (ie, for the QTe dispersion index, the mean values and the 97.5th percentiles were, respectively, 65 +/- 18 ms and 97 ms in the HCM group, 41 +/- 25 ms and 79 ms in the LVH group, and 31 +/- 15 ms and 58 ms in the control group). The maximal QT interval was also significantly longer in the HCM group (464 +/- 30 ms) than in the LVH group (436 +/- 32 ms) and the control group (428 +/- 25 ms)

Dispersion of ventricular repolarization in dilated cardiomyopathy

OBJECTIVE: Increased dispersion of ventricular repolarization has been shown to be a marker for increased risk of ventricular tachyarrhythmias in various cardiac disorders. The present study is aimed at comparing the values of four dispersion indices in four clinical groups: normal subjects (n = 23), patients with intraventricular conduction defects (QRS > 0.12 s) without underlying cardiac disease (n = 30), patients with dilated cardiomyopathy (n = 36), and patients with both dilated cardiomyopathy and ventricular conduction defects (n = 18). METHODS: On an averaged cycle from a 10 s record of 15 simultaneous leads (12-lead ECG and XYZ leads), and after interactive editing, four intervals were computed: JTapex, JTend, QTapex and QTend. For each interval, the dispersion is defined as the difference between the maximal and minimal values across the 15 leads. RESULTS: The mean values of all four dispersion indices were significantly smaller in the normal group than in the three other groups (P < 0.001). Among patients with dilated cardiomyopathy, those with intraventricular conduction defects had significantly higher dispersion values than those without, even disregarding the QRS duration (P < 0.01). Thus, patients with both dilated cardiomyopathy and ventricular conduction defects have larger dispersion values than patients with ventricular conduction defects alone (P < 0.01) and than those with dilated cardiomyopathy without intraventricular conduction defects. CONCLUSION: Dispersion of ventricular repolarization is increased in patients with dilated cardiomyopathy, especially in those with ventricular conduction defects, suggesting that they are at higher risk of arrhythmic events

Dispersion of ventricular repolarisation: a marker of ventricular arrhythmias in patients with previous myocardial infarction

Objective-To examine whether, in coronary patients after myocardial infarction, the dispersion of ventricular repolarisation measured through QT and JT intervals from a surface electrocardiogram could allow separation of those with ventricular tachyarrhythmias (VT) complicating their myocardial infarct from those without. Design-A retrospective comparative study. Setting-University hospital. Patients-39 patients with myocardial infarction complicated by VT, 300 patients after myocardial infarction without arrhythmic events, and 1000 normal subjects. The myocardial infarction groups were divided into anterior, inferior, and mixed locations. Interventions-A computer algorithm examined an averaged cycle from a 10 second record of 15 simultaneous leads (12 lead ECG + Frank XYZ leads). After interactive editing, four intervals were computed: QTapex, JTapex, QTend, and JTend. For each interval, the dispersion was defined as the difference between the maximum and minimum values across the 15 leads. Results-The mean values of all four dispersion indices were higher in patients with myocardial infarction than in normal subjects (p < 0.01). In the infarct groups, patients with VT had significantly greater mean and centile dispersion values than those without VT. For instance, the 97.5th centile value of QTend was 65 ms in normal individuals, 90 ms in infarct patients without arrhythmia, and 128 ms in those with VT; 70% of the infarct patients who developed serious ventricular arrhythmias had values exceeding the 97.5th centile of the normal group, while only 18% of the infarct patients without arrhythmia had dispersion values above this normal upper limit. Among the infarct patients, nearly half of those (18 of 39) with tachyarrhythmias had dispersion values that exceeded the 97.5th centile of those without arrhythmia. Conclusions-Dispersion of ventricular repolarisation may be a good non-invasive tool for discriminating coronary patients susceptible to VT from those who are at low risk

Implementation of the Louvain program for exercise ECG analysis on a microprocessor system.

Several years ago we developed a computer system for the processing of exercise ECGs: the Louvain program for exercise ECG analysis which runs on a minicomputer "Modcomp Classic" and processes XYZ data remotely collected on digital cartridge at the exercise room. This off-line batch procedure is time consuming for the technician (reading of cartridge), but theoretically could be fast. Our experience shows that the results of the exercise test are provided to the referring physician from one day to one week after the procedure because of delays at different levels. The implementation of the programs in a stand-alone unit can produce the results one minute after the end of the test. This solution obviously is more satisfactory for routine clinical testing