ABC | Volume 111, Nº1, July 2018

Original Article Bassi et al T2DM and HTN on HRV and cardiorespiratory status Arq Bras Cardiol. 2018; 111(1):64-72 Table 2 – Linear and non-linear HRV indices for both groups in resting conditions Variables DMT2 (n = 32) DMT2+HTN (n = 28) p value Linear Mean RR intervals (ms) 871.5 ± 105.8 801.1 ± 89.0* 0.010 RMSSD (ms) 17.9 ± 11.1 21.2 ± 15.2 0.358 STD RR 29.3 ± 21.5 31.5 ± 23.2 0.718 LF (nu) 66.3 ± 19.8 59.7 ± 22.9 0.247 HF (nu) 33.7 ± 19.8 40.3 ± 22.9 0.241 TINN 110.5 ± 59.8 121.3 ± 67.5 0.523 RR Tri 5.5 ± 2.6 7.1 ± 4.5 0.082 Nonlinear SD1 14.5 ± 8.2 9.5 ± 4.4* 0.021 SD2 40.4 ± 20.0 43.0 ± 23.1 0.662 SE 3.2 ± 0.3 3.0 ± 0.3* 0.012 ApEn 14.5 ± 8.2 9.5 ± 4.4* 0.021 SampEn 1.4 ± 0.3 1.5 ± 0.3 0.601 CD 1.2 ± 1.3 1.6 ± 1.6 0.271 Data are expressed as Mean ± SD. HRV: heart rate variability; RMSSD: square root of the mean squared differences of successive RR intervals; STD RR: standard deviation of RR; LF nu: normalized unit in the low frequency band; HF nu: normalized unit in the high frequency band; TINN: baseline width of the RR intervals histogram; RR tri: integral of the RR interval histogram divided by the height of the histogram; SD: standard deviation of instantaneous RR interval variability, SE: Shannon Entropy; ApEn: approximate entropy; SampEn: sample entropy, CD: correlation dimension. * p < 0.05, unpaired Student’s t-test. Table 3 – Cardiopulmonary exercise testing responses Variables T2DM (n = 32) T2DM+HTN (n = 28) p value VO 2 (ml.Kg -1 .min -1 ) 22.6 ± 7.5 20.4 ± 3.5 0.18 VCO 2 (mL.min -1 ) 2126.7 ± 673.5 2186.8 ± 510.3 0.72 V E (L.min -1 ) 63.9 ± 19.7 69.5 ± 15.7 0.26 RER 1.2 ± 0.1 1.2 ± 0.1 0.59 V E /VCO 2 slope 28.4 ± 4.6 29.9 ± 4.6 0.27 CP (mmHg .ml.kg −1 min −1 ) 4902.7 ± 2004.9 4642.3 ± 1157.1 0.58 VP (mmHg) 1.4 ± 0.5 1.5 ± 0.4 0.26 SBP rest (mmHg) 130.03 ± 16.08 137.6 ± 17.4 0.10 DBP rest (mmHg) 86.7 ± 7.6 92.7 ± 11.2‡ 0.02 SBP peak (mmHg) 209 ± 32.1 225.4 ± 24.6‡ 0.04 DBP peak (mmHg) 100.38 ± 16.35 104.1 ± 16.4 0.41 Workload (watts) 125.4 ± 37.4 126.5 ± 36.5 0.92 Data are expressed as Mean ± SD. ‡ Unpaired Student’s t-test. T2DM: type 2 diabetes mellitus; HTN: hypertension; VO 2 : oxygen uptake; VCO 2 : carbon dioxide production; RER: respiratory exchange ratio; VE/VCO 2 slope: minute ventilation/carbon dioxide output relationship from the beginning of exercise to peak exercise; CP: circulatory power; VP: ventilator power; SBP: systolic blood pressure, DBP: diastolic blood pressure. Discussion Summary of findings Themain findings of the present study are: (i) individuals with DMT2 associated with HTN, even when controlled, presented with a greater impairment in linear and nonlinear HR dynamics compared to those with only DMT2; (ii) novel CPET derived parameters, confirming our hypothesis. To our knowledge, this is the first study to address nonlinear HR dynamics in this specific population. The findings of the present study stress the clinical importance of early evaluation of the cardiac nervous system functionality, once the association between T2DM and HTN alters the cardiac autonomic modulation. 68