ABC | Volume 115, Nº1, July 2020

Original Article Vargas & Rigatto Parents’ BP and young men autonomic impairment Arq Bras Cardiol. 2020; 115(1):52-58 Discussion In the present study, there was no significant difference between the groups in terms of FMD, SBP, DBP or VO 2max . Thus, our results suggest that the differences found between the FM-N and FM-H groups in relation to cardiovascular autonomic modulation are due to the family history of hypertension of the athletes, regardless of the other variables studied. According to the literature data, the prevalence of hypertension appears to affect about 30% to 45% of the general population. 13 In our study, we found a prevalence of 53.3% for the athletes’ parents (Table 1), values above the world average. We believe that socioeconomic factors can explain the differences found in our sampling. Our results provide, for the first time, evidence that family history of hypertension might be crucial to the progressive imbalance of autonomic regulation in healthy young athletes with normal BP. Based on our knowledge, this is the first study to show the possible early involvement of the autonomic modulation in the hypertensive process. Solanki et al. 16 examined sympathetic function tests of young nonathletic males, considering measures of obesity, PA and familial hypertension. Their results showed that the cardiac autonomic function is altered in individuals with a family history of hypertension. Autonomic imbalance changes due to increased sympathetic tone was more pronounced in subjects with a family history of hypertension. These findings by Solanki and co-workers 16 are in agreement with our results, and also highlight the importance of physical exercise, which countered the autonomic imbalance in favor of normal EF for all study subjects, regardless of the experimental group. At least partially, it is reasonable to believe that our results point out towards the fact that the first changes in the hypertensive process affect the sympathetic and parasympathetic systems. These conclusions are in agreement with Vargas et al., 11 who also showed that in athletes a small increase in BP induces changes in the autonomic nervous system without changing the EF or VO 2max . Considering that the autonomic regulation can be assessed with a non-invasive approach to evaluate the HRV in the time and frequency domains, 8 it could be useful to detect its impairment and provide the physicians with valuable information to assess the treatment efficacy or even to prevent diseases. Despite the enormous impact of a decrease in HRV over the cardiovascular risk, we did not find any researches in the literature showing a correlation between the family history of hypertension and these parameters in healthy subjects. We believe that our results may drive the attention to a method that is easy, of low cost and able to present data associated to a significant cardiovascular risk, such as HRV. They will contribute not only to prevent hypertension in subjects who are at genetic risk, but also to open up a new possibility of monitoring hypertensive patients. Table 2 – Measurements of parents’ systolic and diastolic blood pressure FM-N (n=14) F-H (n=11) M-H (n=10) FM-H (n=11) Father Mother Father Mother Father Mother Father Mother SBP (mmHg) 129 (120-188) 124 (120-130) 147 (130-177) 124 (120-127) 124 (120-127) 158 (143-184) 154 (130-193) 152 (130-184) DBP (mmHg) 86 (75-105) 84 (77-90) 97 (85-110) 83 (77-88) 85 (80-89) 96 (80-120) 98 (85-110) 96 (80-120) PAS: pressão arterial sistólica; PAD: pressão arterial diastólica. Os valores correspondem à média (inrervalo de confiança). Table 3 – Heart rate, time-domain and frequency-domain measurements of resting heart-rate variability FM-N (n=14) F-H (n=11) M-H (n=10) FM-H (n=11) RMSSD (ms) 210.2 (229) 179.1 (187,9) 125.2 (164.2) 82.2 (65)* NN50(count) 356±82 260±50 296±81.3 218.8±44* pNN50 (%) 31.5±6.4 23.6±3.4 25.8±6.3 20.2±4.5* HRV triangular index 26.6±7 21.9±6.1 20.8±7.4 17.2±2.5* SDNN (ms) 256 (145) 211.1 (123.1) 185.3 (84.3) 162.4 (92.7)* HFa (ms) 15935 (31705.1) 13822.5 (22099.8) 3421 (24564.2) 3025.1 (15568.9) HFnu (%) 48.6±8.6 40.3±13 38.4±10.3 33.8±11.2* LFa (ms) 13654 (54544.1) 11575.2 (53678.3) 2591.8 (9127.9) 3173.4 (13163.2) LFnu (%) 51.4±8.6 59.7±13 61.6±10.3 66.2±11.2* LF/HF (ms2) 1(0.5) 1.5 (1.4) 1.8 (0.3) 2.5 (1.3)* Values are expressed as mean ± SD when parametric data, or median (interquartile range) when non-parametric data. *Avalue of p < 0.05 was considered statistically significant when compared to the group FM-N. RMSSD: square root of the mean squared differences among consecutive RR intervals; NN50: the number of successive NN intervals greater than 50ms; pNN50; the ratio derived by dividing NN50 by the total number of NN intervals; HRV: heart rate variability; SDNN: standard deviation of normal RR intervals; HFa: absolute values of high-frequency components; nu: normalized units; LFa: absolute values of low-frequency components; LF/HF: ratio between low- and high-frequency power components. 55