Dados do Trabalho

Título

Obstructive sleep apnea and heart rate variability assessed by ambulatory blood pressure monitoring in seniors with diabetes. A propensity score matched case-control study

Introdução

Impaired heart rate variability (HRV) in continuous ECG recordings is an index of cardiovascular risk. Increased HRV during sleep, estimated from ambulatory blood pressure monitoring (ABPM-HRV), has been described as a predictor of cardiovascular events in type 2 diabetes mellitus (T2DM). Obstructive sleep apnea (OSA) is common in T2DM and could explain the increased nighttime ABPM-HRV in T2DM.

Objetivo

Identify whether the HRV is higher in diabetic seniors in comparison with non-diabetic seniors controls.

Métodos

Community-dwelling and physically independent persons aged 65 years and older of both sexes were recruited from an ongoing cohort study that performs respiratory polygraphy and ambulatory blood pressure monitoring at 15-minute intervals during the day and 20- minute intervals during the night. ABPM-HRV was estimated from the standard deviation (SD) and coefficient of variation (CV) of heart rate. Non-diabetic controls were matched by age, sex and body mass index using the propensity score Diabetic vs. non-diabetic and OSA vs. non-OSA comparisons were performed to assess their associations with daytime and nighttime ABPM-HRV.

Resultados

Among the 429 subjects in the cohort, we found 90 T2DM cases and were able to match 90 non-diabetic controls. In univariate analysis, participants with T2DM showed a 24-hour ABPM-HRV CV lower than the controls: 11.7 ± 4.2 vs. 13.4 ± 4, respectively; P=0.006. Adjusting for AHI and usual confounders the difference is still significant (P=0.017).

Conclusões

Reduced HRV was independently associated with T2DM. This may contradict a previously reported hypothesis that OSA could participate in increasing nighttime ABPM-HRV in T2DM. The present results in seniors warrant further research on the mechanisms of the OSA-HRV relationship.

Palavras-chave

cardiovascular system; obstructive sleep apnea (OSA); diabetes mellitus; arterial pressure.