The smoking habit negatively influences autonomic heart control in community-dwelling elderly adults

The present study aimed to analyze the influence of smoking on heart autonomic control in elderly adults who did and did not smoke.

In a population-based study, all community-dwelling elderly adults (≥60 years old) from Aiquara, Bahia, Brazil, were invited to participate in the study. Two-hundred-thirty-two (232) elderly adults provided information about their smoking habits and underwent 5-min recordings of successive RR intervals. Analysis of the variability of the RR intervals was performed in time and frequency domains and with nonlinear methods. The HAC parameters were adjusted for the following potential confounders: age, sex, diabetes, beta-blocker use, cardiovascular disease, body mass index and physical activity level. After exclusions, 210 elderly adults were divided into 2 groups, nonsmokers or those who stopped smoking (NSMOK [n=190]) and current smokers (SMOK [n=20]). Owing to the absence of a normal distribution, the Mann-Whitney test was used for group comparisons.

For unadjusted HAC parameters, a significant difference was observed (p<0.05) between groups for the following parameters in the time domain: CV_RR; SDNN; RMSSD; pNN50; triangular index TINN; and nonlinear parameters SD1, SD2 and D2. All of the adjusted HAC parameters (including the Mean RR and frequency domain parameters) were significantly different between the groups.

Together, the HAC parameters indicated a higher variability of successive RR intervals in NSMOK elderly adults. Notwithstanding, adjustment of the HAC parameters was an important step to improve data analysis. These results indicate an impaired sympathovagal balance on the heart of elderly adult smokers.