Comparação da capacidade diagnóstica de diferentes métodos para avaliação da disfunção autonômica cardíaca em indivíduos com pré-diabetes e diabetes tipo 2

Abstract

Diabetes Mellitus (DM) is a risk factor for several systemic complications, including cardiovascular autonomic neuropathy (CAN), a clinically relevant but underdiagnosed condition. The present study evaluated the diagnostic capacity of resting and post-exercise heart rate variability (HRV) and heart rate recovery (HRRec) for identifying CAN in individuals with pre-DM and type 2 DM (T2DM). Seventy-two individuals were recruited and divided into preDM (n=23; fasting glucose 100 to 125 mg/dL or glycated hemoglobin 5.7 to 6.4%), T2DM (n=27; fasting glucose ≥ 126 mg/dL or HbA1c ≥ 6.5%) and normoglycemic individuals (n=22; no diagnosis of DM or pre-DM; fasting glucose <100 mg/dL or glycated hemoglobin <5.7%). The presence of CAN was assessed by cardiovascular autonomic reflex tests (i.e., HR response to the Valsalva maneuver; HR variation during deep breathing; blood pressure response to sustained handgrip; immediate HR response and BP upon standing). Resting HRV was assessed by time domain indices (SDNN, RMSSD, pNN50, SD1, SD2, SD1/SD2) and frequency domain indices (LF ms², HF ms², LF un., HF un., LF/HF, Total Power). Post-exercise physical HRV was assessed by the RMSSD index (calculated over the first minute (RMSSD1min), the second minute (RMSSD2min) and the first two minutes of recovery (RMSSD0-2min) after the Incremental Shuttle Walking Test – ISWT). HRRec was calculated using the recovery deltas of 1 and 2 minutes after the ISWT. The autonomic indices described above were compared between the DM2, pre-DM and normoglycemic groups. Subsequently, the DM2 and pre-DM groups were grouped (n=50) and the diagnostic capacity of the HRV and HRRec indices was calculated by means of ROC curve analysis and subsequent calculation of sensitivity and specificity, considering the capacity of each index to identify CAN in comparison to the gold standard (i.e., by cardiovascular autonomic reflex tests). The SDNN, RMSSD, pNN50, HF abs. and SD1 indices of resting HRV showed better performances diagnostics (AUC: 0.507-0.755; p<0.05). Regarding recovery indices, the best performance was of ∆RecHR 2nd minute (AUC= 0.672; p=0.04). Our study highlights the potential of resting HRV and ∆RecHR in the 2nd minute in monitoring CAN in individuals with T2DM and pre-DM. Future studies should explore the clinical applicability of these indices in different contexts and clinical scenarios.