[The influence of exercise and dobutamine-induced ischemia on the presence of late potentials in patients after myocardial infarction].

UNLABELLED

The aim of this study was to examine the influence of transient exercise- and dobutamine-induced myocardial ischemia on time domain parameters of signal-averaged ECG (SAECG) and presence of late potentials (LP) in patients after myocardial infarction (MI). The investigation covered 85 patients after healing of MI, divided into two groups. Group I (24 males and 2 females, mean age 56.8 +/- 6.4 yrs) had exercise-induced ischemia and group II consisted of 59 patients (51 males and 8 females, mean age 58.3 +/- 8.5 years) with ischemia provoked by the intravenous dobutamine stress-testing. In each patient 2-D echocardiography, 24-h ambulatory Holter ECG, coronary arteriography were performed before stress testing. The ischemia was proven by using Tc-99m. MIBI myocardial perfusion and standard 12-lead ECG monitoring. Recordings of SAECG were registered at rest and during ischemia under influence of stress-testing. The following time-domain parameters of SAECG were analysed: the root-mean-square voltage of the last 40 and 50 ms of the filters QRS complex (RMS40, 50), total time duration of filtered QRS (t-QRS) and duration of signals lower than 40 microV (LPD). LP were detected when two or three of following criterias had been registered: RMS 40 < 20 microV, t-QRS > 114 ms, LPD > 38 s. There was no statistically significant differences in all time domain parameters of SAECG between records at the baseline and during ischemia in each study group. At the baseline LP have been registered in 11.5% and in 15% patients, respectively of group I and group II. On the top of ischemia during treadmill exercise stress-testing LP have been recorded in 27% subjects. Under influence of dobutamine-provoked ischemia LP have been registers in 25% patients.

CONCLUSION

Exercise- and dobutamine-induced ischemia triggers development of LP in small grade in post-infarction patients.