Clinical aspects of myocardial electrical instability in chronic IHD

The aim of the study was to assess associations between myocardial electrical instability estimates (heart rhythm turbulence, T- wave microvolt alternation, QT dispersion) and structural and functional changes in heart in the settings of IHD with ventricular premature beats. Eighty two subjects with exertional angina (NYHA FC II-III) and Lown Grade 3-5 class ventricular arrhythmia were examined. Controls included 28 pts. with chronic IHD with no arrhythmias. Heart rhythm turbulence, T- wave alternation and QT dispersion were defined based on 12-lead ECG data with record duration of 5 minutes using Intecard-7 apparatus. All patients underwent common clinical examination, 60-lead electrocardiogram (ECTG-60), ECG daily monitoring test (SMECG) (Cardian, Belarus), bicycle ergometric test, short ECG recording vagal sympathetic balance was estimated (using Briz Program Package and SMECG). IHF subjects who had Lown Grade III-V class ventricular arrhythmia had a higher frequency of heart rhythm turbulence disturbance, higher T microvolt alternation estimates and QT dispersion. Close relationship between myocardial electrical instability parameters (heart rhythm turbulence, T microvolt alternation and QT dispersion) and myocardial ischemic signs, LVEF, and heart rhythm variability in chronic IHD have been identified.