OBJECTIVE
To identify previously unknown laboratory and instrumental indicators that affect the elongation of corrected QT interval (cQT) on electrocardiogram (ECG) in patients with arterial hypertension (AH) and nonalcoholic fatty liver disease (NAFLD).
MATERIAL AND METHODS
A cross-sectional comparative study, which included 107 patients aged from 45 to 65 years with grade I-II of AH (with NAFLD (fatty liver index FLI >60) and without it), has been performed. A clinical examination included anamnesis analysis, assessment of general condition, measurement of office blood pressure, calculation of heart rate, analysis of anthropometric data (height, weight, body mass index (BMI)). The structural state of liver was evaluated by ultrasound examination, for which the Sonoline G 50 («Siemens AG, Medical Solutions», Germany) medical diagnostic ultrasonic device was used. Moreover, the fatty liver index (FLI) was calculated. All patients underwent echocardiography with assessment of epicardial adipose tissue thickness (EAT) and a 12-lead ECG with the calculation of cQT according to the Bazett formula (where normal values are 340—450 for men and 340—460 for women). Lipid metabolism was analyzed using the extended lipidogram which contains total cholesterol, its fractions and triglycerides.
RESULTS
The comparison groups were matched in estimating the main clinical and demographic indicators. BMI was statistically significantly higher in patients with AH and NAFLD, that can be explained by the pattern of comorbid pathology. Patients with comorbid pathology had higher levels of very-low-density lipoproteins cholesterol (p=0.002), triglycerides (p<0.001) and lower levels of high-density lipoproteins cholesterol (p<0.001) while indicators of lipid and glucose metabolism were assessed. The above mentioned suggests a negative proatherogenic lipid profile of this category of patients (IIb and III phenotypes). FLI values (p<0.001) were predictably higher in patients with AH and NAFLD compared to patients with AH and without NAFLD. Moreover, patients with comorbid pathology had a higher EAT thickness (p<0.001). It was established, that patients with AH and NAFLD more frequently had cQT interval elongation (more than 450 ms in men and 460 ms for women) (16 (31.4)% in comparison with 8 (14.3)%, p=0.039) compared to patients with AH and without NAFLD, that shows a presence of higher risk of arrhythmia and sudden cardiac death development in this category of patients. The performed ROC-analysis of correlation between cQT interval elongation prognosis on ECG and FLI indicator showed, that a high risk of cQT interval elongation on ECG is predicted at FLI ≥66.5. It was noted, that the increase of EAT thickness on 1 mm was associated with increase of cQT on 29.6 ms, while the dependence of cQT from EAT thickness was estimated by conduction of linear regression.
CONCLUSION
This study showed, that patients with arterial hypertension and nonalcoholic fatty liver disease have a statistically significantly higher corrected QT interval elongation on ECG compared to patients with arterial hypertension and without nonalcoholic fatty liver disease. Furthermore, a statistically significant correlation between QT interval duration and fatty liver index has been found. Thus, a high risk of corrected QT interval elongation above accepted normal values is predicted when FLI ≥66.5. Moreover, it has been established, that increase of epicardial adipose tissue thickness in patients with arterial hypertension and nonalcoholic fatty liver disease on 1 mm was associated with increase of corrected QT interval on 29.6 ms. The above mentioned may indicate a greater risk of cardiovascular events in this category of patients, and this must be considered during treatment by medicines that elongate the QT interval.
