Effects of smoking status, history and intensity on heart rate variability in the general population: The CHRIS study

Abstract

Background Heart rate variability (HRV) reflects the autonomous nervous system modulation on heart rate and is associated with several pathologies, including cardiac mortality. While mechanistic studies show that smoking is associated with lower HRV, population-based studies present conflicting results. Methods We assessed the mutual effects of active smoking status, cumulative smoking history, and current smoking intensity, on HRV among 4751 adults from the Cooperative Health Research In South Tyrol (CHRIS) study. The HRV metrics standard deviation of normal-to-normal (NN) inter-beat intervals (SDNN), square root of the mean squared differences of consecutive NN intervals (RMSSD), total power (TP), low (LF) and high frequency (HF) power, and their ratio (LF/HF), were derived from 20-minute electrocardiograms. Smoking status, pack-years (PY), and tobacco grams/day from standardized questionnaires were the main exposures. We fitted linear mixed models to account for relatedness, non-linearity, and moderating effects, and including fractional polynomials. Results Past smokers had higher HRV levels than never smokers, independently of PY. The association of HRV with current smoking became apparent when accounting for the interaction between smoking status and PY. In current smokers, but not in past smokers, we observed HRV reductions between 2.0% (SDNN) and 4.9% (TP) every 5 PY increase. Furthermore, current smokers were characterized by dose-response reductions of 9.8% (SDNN), 8.9% (RMSSD), 20.1% (TP), 17.7% (LF), and 19.1% (HF), respectively, every 10 grams/day of smoked tobacco, independently of common cardiometabolic conditions and HRV-modifying drugs. The LF/HF ratio was not associated with smoking status, history, or intensity. Conclusions Smoking cessation was associated with higher HRV levels. In current smokers, heavier smoking intensity appears gradually detrimental on HRV, corroborating previous evidence. By affecting both the sympathetic and parasympathetic nervous system indexes, but not the LF/HF balance, smoking intensity seems to exert a systemic dysautonomic effect.

Effects of Cigarette Smoking on Cardiac Autonomic Responses: A Cross-Sectional Study

“…These changes are suggestive of increased sympathetic nervous system activity. The results are in line with those of Murgia [ 22 ] who also observed decreased HRV, with a stronger correlation between SDNN and TP with every 5 pack-year increase and dose-response reductions in SDNN, RMSSD, TP, LF, and HF.…”

“…In 2005, Kobayashi [ 21 ] found that LF/HF is significantly increased immediately after smoking. Since these influences may have affected the results of some earlier studies that included people who smoked shortly before the autonomic test, several other papers have attempted to quantify ANS in smokers after a few hours of abstinence [ 22 , 23 ]. Yet, these studies yielded conflicting results and were difficult to interpret in light of comorbidities [ 22 ].…”

“…Since these influences may have affected the results of some earlier studies that included people who smoked shortly before the autonomic test, several other papers have attempted to quantify ANS in smokers after a few hours of abstinence [ 22 , 23 ]. Yet, these studies yielded conflicting results and were difficult to interpret in light of comorbidities [ 22 ]. For example, in 2019, Murgia and colleagues [ 15 ] found a significant relationship between decreased HRV parameters (SDNN and TP) with every 5 pack-year increase.…”

The Association of Autonomic Nervous System Function With Ischemic Stroke, and Treatment Strategies

“…However, despite experimental studies showing negative effects of smoking on changes in HRV, population-based studies show conflicting results. Recently, a population-based epidemiological study reported that heavier smoking intensity was gradually detrimental to HRV, while smoking cessation increased HRV levels, suggesting that heavy smoking is an independent risk factor for a systemic dysautonomic effect (82). In addition, tobacco cigarette smoking has a negative influence on physiological responses and exercise performance, characterized by a significantly attenuated exercise-induced HR response and altered HRV (83).…”

The cholinergic anti-inflammatory pathway in chronic kidney disease—review and vagus nerve stimulation clinical pilot study

“…Low-frequency (LF) power mainly reflects the sympathetic tone, whereas high-frequency (HF) power correlates more with the parasympathetic tone [ 40 ]. HRV is also significantly influenced by sex, age, physical fitness, clinical comorbidities, smoking and medication [ 41–44 ]. Additional factors linked to decreased HRV are metabolic (diabetes, early stages of glucose intolerance and metabolic syndrome), endocrine (cortisol) and barometric (orthostatic) [ 45–47 ].…”