Dependence of QT (QTc) interval duration on the blood pressure level in patients with arterial hypertension

Introduction. Arterial hypertension is associated with electric instability of the myocardium and the development of fatal ventricular arrhythmias. One of the main causes for the electric instability of the myocardium is the in homogeneity of the ventricular repolarization processes, which can be estimated by studying QT interval duration and dispersion. Objectives.To study the dependence of QT interval (QTc) duration on the level of blood pressure in patients with arterial hypertension using a standard ECG recording and an ambulatory ECG monitoring. Materials and methods. Were examined147 patients, 124 of which with arterial hypertension and 23 without arterial hypertension. Patients were divided into 5 groups according to their blood pressure level: group 1 – normal or elevated blood pressure on a background of antihypertensive therapy: 56 patients (38.1 %), group 2 –grade 1 hypertension; 39 patients (26, 5 %), group 3 –grade 2 hypertension: 22 patients (15 %), group 4 –grade 3 hypertension: 7 patients (4.8 %), the fifth group – normal or elevated pressure: 23 patients, which is 15.6 % (comparison group, without arterial hypertension). The study of the dependence of QT interval (QTc) duration on the level of BP was carried out according to the analysis of the data of standard ECG, ECG Holter monitoring and 24-hour blood pressure monitoring. Results. A statistically significant regression dependence of the duration of minimal nocturnal QT intervals and corrected QTc on the stage of arterial hypertension in groups 1 and 4 with p < 0.05 was establishedon the basis of Student's t-test for independent samples. Conclusions. There was a statistically significant regression dependence of the minimum QT interval at night and the minimum corrected interval QTc at night on the daily level of variability 1 of systolic blood pressure, which indicates a direct dependence of the QT interval and QTc on blood pressure.