Вопросы современной педиатрии (Nov 2019)
Cardiac Autonomic Neuropathy and Hypoglycemia as Independent Predictors of QTc Elongation at Night in Adolescents With Type 1 Diabetes: Cohort Study
Abstract
Background. QTc elongation is the risk factor of sudden cardiac death. Patients with type 1 diabetes (T1D) can have QTc elongation due to hypoglycemia and cardiac autonomic neuropathy (CAN). The separate role of this two factors in QTc elongation development in T1D patients is still unknown.Objective. The aim was to study the role of cardiac autonomic neuropathy and hypoglycemia as independent risk factors of QTc elongation at night in adolescents with T1D.Methods. Patients at the age of 10-17 years old with T1D were enrolled in the cohort study. All patients have undergone simultaneous 24-hour monitoring of electrocardiogram and glycemia. Results of nocturnal monitoring (23:00-07:00) were estimated. QTc elongation > 450 ms was regarded pathological. CAN was diagnosed at decrease of ≥ 2 time domain parameters (SDNN < 101 ms, SDNNi < 48 ms, SDANN < 85 ms, rMSSD < 25 ms). Hypoglycemia was classified as 1st (≥ 3.0 and ≤ 3.9 mmol/L), 2nd (≥ 2.2 and < 3.0 mmol/L) or 3rd (≤ 3.9 mmol/L along with cognitive defects and the need of acute hypoglycemia treatment) level. We also have distinguished prolonged (< 3.0 mmol/L and ≥ 120 min) and asymptomatic (≤3.9 mmol/L and no adrenergic symptoms) nocturnal hypoglycemia. We didn’t analyse hypoglycemia periods with > 9.0 mmol/L.Results. QTc elongation > 450 ms was revealed in 28 out of 100 patients. All patients with QTc > 450 ms were similar on gender, age, HbA1C level with patients without any QTc elongation but they have longer history of T1D and higher frequency of 2nd level hypoglycemia and asymptomatic nocturnal hypoglycemia. According to the data from multivariate regression analysis independent predictors of QTc elongation were the following: CAN — odds ratio (OR) 9.0 (95% confidential interval [CI] 3.3-24.2), 2nd level hypoglycemia — OR 4.4 (95% CI 1.4-14.2), asymptomatic nocturnal hypoglycemia — OR 2.9 (95% CI 1.1-7.7) and T1D duration — OR 1.3 (95% CI 1.0-1.5).Conclusion. CAN and hypoglycemia (both clinically significant and asymptomatic nocturnal) are independent predictors of QTc elongation in adolescents with T1D.
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