The clinical and functional evaluation of cardiac electrical instability in patients with silent myocardial ischemia

Abstract

Aim. To study markers of myocardial electrical instability in patients with coronary heart disease (CHD) during silent myocardial ischemic episodes. Subjects and methods. Eighty-two patients with stable CHD (mean age 62.6 ± 5.4 years) were examined. In addition to standard physical examination, a complex of their study comprised 12-lead electrocardiography (ECG), Holter ECG monitoring, exercise testing, echocardiography, average signal (AS) ECG recording with identification of late ventricular potentials (LVP), analysis of cardiac rhythm variability (CRV), and estimation of QT interval duration. Results. The study revealed that a combination of Holter ECG monitoring and exercise testing (bicycle ergometry) was required to diagnose silent CHD and to evaluate functional condition severity. Diurnal myocardial ischemia and the number of silent ischemic episodes were found to associate with AS-ECG readings, QT interval dispersion, and LF/HF ratio. In patients with silent CHD, the incidence of Q-wave myocardial infarction and the frequency of high-grade ventricular premature beats were higher, late ventricular potentials were more frequently found, and autonomic vegetative control of sinus rhythm proved to be more significantly impaired. Conclusion. No pain signal in patients with CHD leads to underestimation of the seriousness of the situation and, accordingly, to inadequate measures for its elimination therefore early diagnosis and correction of silent myocardial ischemia are prognostically important in preventing life-threatening acute manifestations of CHD and arrhythmic complications.

Keywords

• silent myocardial ischemia
• cardiac electrical instability