Heart rate variability and plasma lipids in men with and without ischaemic heart disease

Cholesterol, triglycerides, HDL, and nitric oxide as determinants of resting heart rate variability in non-hospitalized mild post-COVID individuals: a cross-sectional study

BACKGROUND

The association between plasma lipids, nitric oxide (NO) and cardiovascular risk has been well documented in the literature, however, the association between these outcomes and heart rate variability (HRV) in COVID-19 remains incipient as there is no scientific evidence that has investigated this outcome.

OBJECTIVE

Investigate whether metabolic outcomes may be associated with cardiac autonomic behavior arising from short-term HRV variables in non-hospitalized mild post-COVID individuals.

METHODS

This is a cross-sectional study. Individuals of both sexes, aged ≥ 18 years, who tested positive for SARS-CoV-2 according to the RT-PCR test, without the need for hospitalization, were included. The HRV was collected in the supine position for at least 10 min for later analysis in the Kubios software. Metabolic outcomes [high density lipoprotein (HDL) (mg/dL), cholesterol (mg/dL), triglycerides (mg/dL) and NO (µmol/L)] were collected through a blood sample.

RESULTS

Seventy-three individuals were included (post-COVID = 32; control = 41). HRV was worse in the post-COVID group when compared to the control group (p < 0.05). Cholesterol, HDL, triglycerides and NO showed significant correlations with HRV indices. Regression models indicated that cholesterol and triglycerides, as well as NO, explain up to 30.3% of the variations in certain HRV indices, suggesting an impact of metabolic outcomes on autonomic modulation.

CONCLUSION

There is a relationship between plasma lipids, NO and HRV in non-hospitalized individuals with mild COVID-19. Metabolic outcomes are associated and explain between 16.6% and 30.30% of certain variables of resting HRV in post-COVID individuals.

CLINICAL TRIAL NUMBER

Not applicable.

Autonomic Changes Associated with Clinical Depression as Assessed by Short-term Heart Rate Variability (HRV): A Comparative Study

Background

In the present scenario, mental health issues have become a global burden. Among all the mental disorders, depression is one of the most disabling and has been a known cardiovascular risk. Autonomic attenuation is put forth as the cause. The literature available on the connection between clinical depression and cardiac autonomic attenuation is limited and inconclusive. Hence, to provide more clarity, with the aid of short-term heart rate variability (HRV), autonomic changes in clinically depressed individuals were assessed.

Methods

Based on the set criteria, we recruited 82 subjects from the hospital's outpatient department after ethical approval. Among them, 41 were depressed individuals, and the rest were non-depressed healthy controls. Depressed individuals were categorized based on their Hamilton scores. Both the groups were subjected to short-term HRV, the measures obtained were compared, and the HRV measures of the depressed individuals were correlated with their Hamilton scores.

Results

HRV measures that reflect cardiovagal activity were found to be significantly less (p = .026) in the depressed individuals. No gender-influenced differences were observed among the depressed. Groups with different levels of depression also revealed no significant differences in their autonomic activity. Hamilton scores of the depressed individuals exhibited no significant correlation with their HRV parameters.

Conclusion

Based on our HRV findings, we conclude that the depressed individuals have reduced cardiovagal activity.

Autonomic Nerve Function Predicts Risk of Early Death after Discharge in Acute Medical Disease

BACKGROUND

Heart rate variability, a marker of autonomic function, has shown promising prognostic results in specific populations, but has not been tested in a general medical population. We hypothesized that heart rate variability identifies high-risk medical patients early after admission to the hospital.

METHODS

This was a single-center prospective cohort study of acutely admitted medical patients aged ≥18 years with a life expectancy ≥3 months, included between 2019-2023. Unstable patients needing direct admission to the intensive care unit were excluded. Heart rate variability was recorded within 24 hours of admission for 10 minutes. The standard deviation of normal-normal beats (SDNN) was the primary heart rate variability marker. Low SDNN was defined as the lowest tertile (≤22 ms). The primary outcome was 30-day all-cause mortality. The secondary outcome was 30-day readmission or mortality.

RESULTS

Among 721 patients included, low SDNN carried an 8-fold greater risk of 30-day mortality in univariate analysis (hazard ratio [HR] 8.3; P = .001); in multivariate analyses a 4-fold greater risk (HR 3.8; P = .037). Low SDNN was associated with the combined outcome of 30-day mortality or readmission (HR 1.5; P = .03) in multivariate analysis. In receiver operating characteristics analyses, low SDNN improved the predictive accuracy of early warning score for 30-day mortality or readmission from 0.63 to 0.71 (P = .008) but did not improve the accuracy for 30-day mortality alone.

CONCLUSIONS

In patients admitted due to acute medical illness, low heart rate variability predicted 30-day mortality and readmission, suggesting heart rate variability as a tool to identify patients at high and low risk of relevant endpoints.

Heart rate variability after bariatric surgery: The add-on value of exercise

PURPOSE

To assess the impact of bariatric surgery and an added supervised exercise training programme on heart rate variability (HRV) in patients with severe obesity.

METHODS

Fifty-nine patients who underwent bariatric surgery were randomised in the post-operative period to a 12-week supervised exercise training programme (moderate intensity combination aerobic/resistance exercise training programme) or a control group. Indices of HRV including time-domain, spectral-domain, and nonlinear parameters were measured preoperatively, and at 3, 6, and 12 months.

RESULTS

After the surgical procedure, both groups improved anthropometric parameters. Type 2 diabetes, hypertension, and dyslipidemia resolutions were similar between groups. Total body weight loss at 6 and 12 months were also comparable between groups (6 months: 28 ± 6 vs. 30 ± 6%; 12 months: 38 ± 9 vs. 38 ± 10%; control vs. intervention group respectively). Bariatric surgery improved HRV parameters at 12 months compared to the pre-operative values in the intervention group: standard deviation of R-R interval (SDNN) (156.0 ± 46.4 vs. 122.6 ± 33.1 ms), low frequency (LF) (6.3 ± 0.8 vs. 5.8 ± 0.7 ms²), and high frequency (HF) (5.1 ± 0.8 vs. 4.7 ± 0.9 ms²) (all p<0.001). For the control patients, similar improvements in SDNN (150.0 ± 39.4 vs. 118.8 ± 20.1 ms), LF (6.1 ± 0.9 vs. 5.7 ± 0.8 ms²), and HF (5.0 ± 0.9 vs. 4.7 ± 0.9 ms²) were obtained (all p<0.001). However, there was no add-on impact of the supervised exercise training programme on HRV after 12 months (p>0.05 for all HRV parameters).

CONCLUSION

Bariatric surgery is associated with an improvement in HRV. A supervised exercise training programme in the post-operative period did not modulate further the benefits of bariatric surgery regarding HRV parameters.

Enhancing Inhibitory Control in Older Adults: A Biofeedback Study

Multidomain interventions based on bio-/neurofeedback have proven useful in improving executive functions. The present study aimed to explore the potential efficacy and feasibility of an intervention that combined Heart Rate Variability Biofeedback (HRV-BF) and Near Infrared Hemoencephalography Neurofeedback (nirHEG-NF) on inhibitory control (IC) of healthy older adults. Thirty-four participants were randomly assigned to two groups: the biofeedback group (received a 10-week combined intervention of HRV-BF and nirHEG-NF) and the active control group (received a similar protocol without real-time biofeedback). Besides cognitive outcomes, the study examined pre- and post-changes in autonomic regulation and prefrontal blood oxygenation at rest and during training. Results revealed training-induced inhibitory control gains in one of the two interference tasks, whereas no effect was found on response inhibition. After the intervention, HRV increased in participants with the lowest levels of HRV at baseline. Although older adults increased blood oxygenation during training, no significant pre- and post-changes were found in blood flow oxygenation. These findings not only suggest that HRV-BF and nirHEG-NF potentially improve performance in certain subcomponents of inhibition (i.e., interference vs. response inhibition), but it may also be beneficial for parasympathetic activity in participants with low HRV and for increasing blood flow oxygenation on prefrontal areas during training.

Getting under the skin: long-term links of adolescent peer relationship difficulties to adult vagal tone

Understanding whether and how the absence of positive relationships may predict longer-term physical health outcomes is central to building a working conceptual model of the interplay of social and physical development across the lifespan. This study sought to examine the extent to which difficulties establishing positive social relationships from adolescence onward serve as long-term predictors of low adult vagal tone, which in turn has been linked to numerous long-term health problems. A diverse community sample of 141 individuals was followed via multiple methods and reporters from age 13 to 29. Across this span, social relationship quality was assessed via close friend and peer reports, observations of romantic interactions, and self-reported romantic relationship satisfaction. A range of potential personality and functional covariates was also considered. Vagal tone while at rest was assessed at age 29. Adult vagal tone was predicted across periods as long as 16 years by: adolescents' difficulty establishing themselves as desirable companions among peers; early adults' inability to establish strong close friendships; and lack of warmth in romantic relationships as an adult. Poor early adult friendship quality statistically mediated the link from adolescent peer difficulties to adult vagal tone. A range of potential confounding factors was examined but was not linked to vagal tone. Within the limits of the correlational design of the study, robust connections between adult vagal tone and social relationship quality from adolescence onward suggest at least a possible mechanism by which relationship difficulties may get 'under the skin' to influence future physiological functioning.

Effects of Acute Partial Sleep Deprivation and High-Intensity Interval Exercise on Postprandial Network Interactions

Introduction: High-intensity interval exercise (HIIE) is deemed effective for cardiovascular and autonomic nervous system (ANS) health-related benefits, while ANS disturbance increases the risk for cardiovascular disease (CVD). Postprandial lipemia and acute-partial sleep deprivation (APSD) are considered as CVD risk factors due to their respective changes in ANS. Exercising in the morning hours after APSD and have a high-fat breakfast afterwards may alter the interactions of the cardiovascular, autonomic regulation, and postprandial lipemic systems threatening individuals' health. This study examined postprandial network interactions between autonomic regulation through heart rate variability (HRV) and lipemia via low-density lipoprotein (LDL) cholesterol in response to APSD and HIIE. Methods: Fifteen apparently healthy and habitually good sleepers (age 31 ± 5.2 SD yrs) completed an acute bout of an isocaloric HIIE (in form of 3:2 work-to-rest ratio at 90 and 40% of VO2 reserve) after both a reference sleep (RSX) and 3-3.5 h of acute-partial sleep deprivation (SSX) conditions. HRV time and frequency domains and LDL were evaluated in six and seven time points surrounding sleep and exercise, respectively. To identify postprandial network interactions, we constructed one correlation analysis and one physiological network for each experimental condition. To quantify the interactions within the physiological networks, we also computed the number of links (i.e., number of significant correlations). Results: We observed an irruption of negative links (i.e., negative correlations) between HRV and LDL in the SSX physiological network compared to RSX. Discussion: We recognize that a correlation analysis does not constitute a true network analysis due to the absence of analysis of a time series of the original examined physiological variables. Nonetheless, the presence of negative links in SSX reflected the impact of sleep deprivation on the autonomic regulation and lipemia and, thus, revealed the inability of HIIE to remain cardioprotective under APSD. These findings underlie the need to further investigate the effects of APSD and HIIE on the interactions among physiological systems.

Associations between the rs5498 (A > G) and rs281432 (C > G) polymorphisms of the ICAM1 gene and atherosclerotic cardiovascular disease risk, including hypercholesterolemia

Background

Atherosclerotic cardiovascular disease (ASCVD) originates from complex risk factors, including age, gender, dyslipidemia, obesity, race, genetic and genetic variation. ICAM1 gene polymorphisms are a significant risk factor for ASCVD. However, the impact of the rs5498 and rs281432 polymorphisms on the prevalence of hypercholesterolemia (HCL) has not been reported. Therefore, we determine the relationships between single nucleotide polymorphisms (SNPs), including rs5498 and rs281432 on Intercellular adhesion molecule 1 gene (ICAM1) and ASCVD susceptibility in patients with HCL.

Methods

The clinical characteristics of 278 participants were assessed, and classified to groups having HCL and without HCL. ICAM1 SNPs genotyping was performed by DNA sequencing, and ICAM1 expression was measured using real-time PCR.

Results

Positive dominant model rs5498 participants had twice the risk of HCL (95% confidence interval (CI): [1.24-3.23], P = 0.005). The frequency of the G allele in rs5498 was 1.69 times higher in participants with HCL than in controls (95% CI [1.15-2.47], P = 0.007). Participants with the rs5498 AG or GG variants and high ICAM1 mRNA expression (≥3.12) had 2.49 times the risk (95% CI [1.42-4.38], P = 0.001), and those with a high LDL-C concentration (≥3.36 mmol/L) had 2.09 times the risk (95% CI [1.19-3.66], P = 0.010) of developing ASCVD compared with those with low ICAM1 mRNA and LDL-C levels. Interestingly, participants carrying the rs5498 AG or GG variants who had tachycardia (resting heart rates (RHRs) >100 beats/min) had a 5.02-times higher risk than those with a lower RHR (95% CI [1.35-18.63], P = 0.016).

Conclusions

It may consider the G allele in ICAM1 rs5498 is associated with a higher risk of ASCVD in Thai people with HCL, and is also positively associated with ICAM1 mRNA expression, LDL-C concentration, and RHR.

The relationship between neurocognitive performance and HRV parameters in nurses and non-healthcare participants

Nurses represent the largest sector of the healthcare workforce, and it is established that they are faced with ongoing physical and mental demands that leave many continuously stressed. In turn, this chronic stress may affect cardiac autonomic activity, which can be non-invasively evaluated using heart rate variability (HRV). The association between neurocognitive parameters during acute stress situations and HRV has not been previously explored in nurses compared to non-nurses and such, our study aimed to assess these differences. Neurocognitive data were obtained using the Mini-Mental State Examination and Cognistat psychometric questionnaires. ECG-derived HRV parameters were acquired during the Trier Social Stress Test. Between-group differences were found in domain-specific cognitive performance for the similarities (p = .03), and judgment (p = .002) domains and in the following HRV parameters: SDNN_baseline, (p = .004), LF_preparation (p = .002), SDNN_preparation (p = .002), HF_preparation (p = .02), and TP_preparation (p = .003). Negative correlations were found between HF power and domain-specific cognitive performance in nurses. In contrast, both negative and positive correlations were found between HRV and domain-specific cognitive performance in the non-nurse group. The current findings highlight the prospective use of autonomic HRV markers in relation to cognitive performance while building a relationship between autonomic dysfunction and cognition.

Pathophysiological mechanisms of bradycardia in patients with anorexia nervosa

BACKGROUND

The purpose of this investigation was to examine heart rate variability (HRV), interbeat interval (IBI), and their interrelationship in healthy controls, bradycardic hyperpolarization-activated cyclic nucleotide-gated channel 4 (HCN4) mutation carriers, and patients with anorexia nervosa (AN). We tested the hypothesis that neural mechanisms cause bradycardia in patients with AN. Therefore, we assumed that saturation of the HRV/IBI relationship as a consequence of sustained parasympathetic control of the sinus node is exclusively detectable in patients with AN.

METHODS

Patients with AN between the ages of 12 and 16 years admitted to our hospital due to malnutrition were grouped and included in the present investigation (N = 20). A matched-pair group with healthy children and adolescents was created. Groups were matched for age and sex. A 24-hour Holter electrocardiography (ECG) was performed in controls and patients. More specifically, all patients underwent two 24-hour Holter ECG examinations (admission; refeeding treatment). Additionally, the IBI was recorded during the night in HCN4 mutation carriers (N = 4). HRV parameters were analyzed in 5-minute sequences during the night and plotted against mean corresponding IBI length. HRV, IBI, and their interrelationship were examined using Spearman's rank correlation analyses, Mann-Whitney U tests, and Wilcoxon signed-rank tests.

RESULTS

The relationship between IBI and HRV showed signs of saturation in patients with AN. Furthermore, signs of HRV saturation were present in two HCN4 mutation carriers. In contrast, signs of HRV saturation were not present in controls.

CONCLUSIONS

The existence of HRV saturation does not support the existence of parasympathetically mediated bradycardia. Nonneural mechanisms, such as HCN4 downregulation, may be responsible for bradycardia and HRV saturation in patients with AN.

Autonomic nervous system dysfunction in schizophrenia: impact on cognitive and metabolic health

Schizophrenia (SCZ) is a psychiatric disorder characterized by a wide range of positive, negative and cognitive symptoms, along with an increased risk of metabolic syndrome and cardiovascular disease that contribute to a 15-20-year reduced life expectancy. Autonomic dysfunction, in the form of increased sympathetic activity and decreased parasympathetic activity, is postulated to be implicated in SCZ and its treatment. The aim of this narrative review is to view SCZ through an autonomic lens and synthesize the evidence relating autonomic dysfunction to different domains of SCZ. Using various methods of assessing autonomic activity, autonomic dysfunction was found to be associated with multiple aspects of SCZ pathophysiology, including symptom severity, cognitive impairment, and the development of cardiometabolic comorbidities, such as metabolic syndrome and high BMI. The strongest association of low heart rate variability was noted among patients on antipsychotic treatment with high-affinity muscarinic antagonism (i.e., clozapine, olanzapine and quetiapine). The review will also suggest ways in which studying autonomic dysfunction can help reduce morbidity and mortality associated with SCZ and its treatment.

Targeting the Autonomic Nervous System for Risk Stratification, Outcome Prediction and Neuromodulation in Ischemic Stroke

Ischemic stroke is a worldwide major cause of mortality and disability and has high costs in terms of health-related quality of life and expectancy as well as of social healthcare resources. In recent years, starting from the bidirectional relationship between autonomic nervous system (ANS) dysfunction and acute ischemic stroke (AIS), researchers have identified prognostic factors for risk stratification, prognosis of mid-term outcomes and response to recanalization therapy. In particular, the evaluation of the ANS function through the analysis of heart rate variability (HRV) appears to be a promising non-invasive and reliable tool for the management of patients with AIS. Furthermore, preclinical molecular studies on the pathophysiological mechanisms underlying the onset and progression of stroke damage have shown an extensive overlap with the activity of the vagus nerve. Evidence from the application of vagus nerve stimulation (VNS) on animal models of AIS and on patients with chronic ischemic stroke has highlighted the surprising therapeutic possibilities of neuromodulation. Preclinical molecular studies highlighted that the neuroprotective action of VNS results from anti-inflammatory, antioxidant and antiapoptotic mechanisms mediated by α7 nicotinic acetylcholine receptor. Given the proven safety of non-invasive VNS in the subacute phase, the ease of its use and its possible beneficial effect in hemorrhagic stroke as well, human studies with transcutaneous VNS should be less challenging than protocols that involve invasive VNS and could be the proof of concept that neuromodulation represents the very first therapeutic approach in the ultra-early management of stroke.

Childhood Parental Warmth and Heart Rate Variability in Midlife: Implications for Health

The current study investigated high-frequency heart rate variability (HF-HRV) as a potential mediator between childhood parental warmth and later health and mortality outcomes. Participants were 1,255 adults (56.9% female). Childhood parental warmth was reported retrospectively at mean age 46; resting HF-HRV was measured at mean age 57; cardiovascular health and self-evaluated health were assessed at mean age 57 and 63, and mortality records extracted at mean age 63. Results revealed a positive association between childhood parental warmth and resting HF-HRV, as well as associations between higher HF-HRV and reduced risk of having a later cardiovascular health problem and of mortality by age 63. Mediation analyses revealed a small significant indirect effect of parental warmth, through HF-HRV, on cardiovascular health.

Snacking on Whole Almonds for Six Weeks Increases Heart Rate Variability during Mental Stress in Healthy Adults: A Randomized Controlled Trial

Cardiac autonomic regulation can be indirectly measured by heart rate variability (HRV). Low HRV, which can be induced by mental stress, is a predictor of risk of sudden cardiac death. Few studies have investigated cause-and-effect relationships between diet and HRV. Nut consumption is associated with CVD risk reduction, but the impact on HRV, particularly in response to stress, is unclear. Men and women (30–70 y) with above average risk of developing CVD were randomly assigned in a 6-week randomized, controlled, parallel arm trial to consume either whole almond or isocaloric control snacks (20% of daily estimated energy requirement). Control snacks contained the average nutrient profile of UK snacks. Five-minute periods of supine heart rate (HR) and HRV were measured at resting and during mental stress (Stroop color-word test) at baseline and six weeks. High frequency (HF) power, which reflects parasympathetic regulation of HR, was increased following almonds during the mental stress task relative to control (mean difference between groups 124 ms2; 95% CI 11, 237; p = 0.031, n = 105), but other indices were unaffected. Snacking on whole almonds instead of typical snacks may reduce risk of CVD partly by ameliorating the suppression of HRV during periods of mental stress.

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

Acute ischemic stroke, especially minor stroke, and transient ischemic attack have high risks of recurrence and exacerbation into severe ischemic strokes. It remains challenging to perform risk stratification and screen high-risk groups for initiation of early treatment in these patients. Moreover, with the growing population of patients with chronic small vessel disease, the mechanisms and clinical implications require further investigation. Traditional tools such as the ABCD2 score (age, blood pressure, clinical features, duration of symptoms, diabetes) have only moderate predictive value in patients with transient ischemic attack or minor stroke. By contrast, measurement of changes in heart rate variability (HRV) is an important and novel tool for risk stratification and outcome prediction in patients with cardiovascular diseases, as it reflects the overall level of autonomic nervous system dysfunction. Thus, abnormal HRV may be useful for prognosis and improve stratification of stroke patients with diverse risks. HRV may also partially explain autonomic nervous dysfunction and other manifestations during the process of chronic cerebral small vessel disease. In summary, measurement of HRV may contribute to early initiation of interventions in acute or chronic stroke patients using novel treatments involving rebalancing of autonomic nervous system function.

Influence of physical activity on cardiac autonomic control in patients with dyslipidaemia

The objective of this study was to compare the cardiac autonomic control of dyslipidaemia patients engaged in different levels of physical activity and to determine the predictive ability of physical activity for cardiac autonomic dysfunction in these patients. This study also aimed to compare the cardiac autonomic control of dyslipidaemia patients and healthy adults. 52 patients (age: 49.1±4.53 years) with dyslipidaemia were recruited along with 16 healthy adults. Physical activity levels were assessed by International Physical Activity Questionnaire, and subjects were divided into three categories – low, moderate, and high physical activity. Heart rate variability (HRV) analysis was performed for obtaining time and frequency domain parameters. Presence of cardiac autonomic dysfunction was defined as standard deviation of N-N intervals <44 ms. HRV parameters were compared between 3 groups of dyslipidaemia patients and healthy controls. Predictive ability of physical activity for cardiac autonomic dysfunction in dyslipidaemia was evaluated after adjusting clinical covariates. There was a significant difference between low-frequency power (cardiac sympathetic control), and ratio of low- and high-frequency (HF) power (sympatho-vagal balance) in low versus moderate physical activity group and low versus high physical activity group (P<0.001). Significant differences were also observed for HFnu power (cardiac vagal activity) and total power between the dyslipidaemia groups. Physical activity was found to be a significant (P=0.03), independent predictor of cardiac autonomic dysfunction in dyslipidaemia patients. Findings of the present study suggest that cardiac autonomic profile of dyslipidaemia patients with different physical activity levels varied significantly. Dyslipidaemia patients engaged in moderate and high physical activity demonstrated significantly less sympathetic activity and better sympatho-vagal balance than those engaged in low levels of physical activity; also, vagal cardiac control was significantly greater in high physical activity group. Lower levels of physical activity determined the presence of cardiac autonomic dysfunction in these patients at an optimal cut-off value of ≤1,558 Metabolic Equivalent of Tasks- min/week.

Reduced heart rate variability in a treatment-seeking early psychosis sample

Reduced cardiac autonomic function is associated with increased risk of cardiovascular disease (CVD), with heart rate variability (HRV) providing an accessible index of cardiac autonomic function. HRV may provide a candidate physiological mechanism linking reduced cardiac autonomic function to increased risk for CVD in schizophrenia illness. This study examines whether HRV is also reduced in a community sample of treatment-seeking participants experiencing early psychosis (n = 48) compared to healthy volunteers (n = 48) and social anxiety control groups (n = 48) matched by gender and age. HRV was assessed during a five-minute interbeat interval recording at rest. Participants also completed self-report psychiatric symptom measures. Early psychosis participants showed significant reductions in HRV compared to social anxiety and healthy control groups. Reductions in HRV were also observed in early psychosis participants taking anticholinergic medications compared to both control groups taking cardio-benign medications or who were non-medicated. Lastly, whether or not early psychosis participants were taking anticholinergic medications was not associated with reductions in HRV. Findings provide preliminary evidence that early psychosis is associated with reduced HRV. This study supports further research with larger sample sizes to precisely determine the influence of anticholinergic drugs on HRV in early psychosis populations.

Autonomic Nervous System and Stress to Predict Secondary Ischemic Events after Transient Ischemic Attack or Minor Stroke: Possible Implications of Heart Rate Variability

Transient ischemic attack (TIA) and minor stroke have high risks of recurrence and deterioration into severe ischemic strokes. Risk stratification of TIA and minor stroke is essential for early effective treatment. Traditional tools have only moderate predictive value, likely due to their inclusion of the limited number of stroke risk factors. Our review follows Hans Selye’s fundamental work on stress theory and the progressive shift of the autonomic nervous system (ANS) from adaptation to disease when stress becomes chronic. We will first show that traditional risk factors and acute triggers of ischemic stroke are chronic and acute stress factors or “stressors,” respectively. Our first review shows solid evidence of the relationship between chronic stress and stroke occurrence. The stress response is tightly regulated by the ANS whose function can be assessed with heart rate variability (HRV). Our second review demonstrates that stress-related risk factors of ischemic stroke are correlated with ANS dysfunction and impaired HRV. Our conclusions support the idea that HRV parameters may represent the combined effects of all body stressors that are risk factors for ischemic stroke and, thus, may be of important predictive value for the risk of subsequent ischemic events after TIA or minor stroke.

Cardiovascular autonomic dysfunction in women with polycystic ovary syndrome: a systematic review and meta-analysis

Recent studies reveal that polycystic ovary syndrome (PCOS) might be associated with cardiovascular autonomic dysfunction, but with inconsistent results. The aim of this meta-analysis was to study whether women with PCOS have cardiovascular autonomic dysfunction. PubMed, Web of Science, Cochrane Library and SCOPUS were searched for studies comparing cardiovascular function between women with PCOS and controls. A random-effects model was used to evaluate cardiac autonomic modulation and muscle sympathetic nerve activity (MSNA) between women with PCOS and controls. Eight studies were included, including 243 PCOS and 211 controls. Overall, women with PCOS had significantly lower standard deviation of normal-to-normal RR intervals (SDNN) and percentage of the number of interval differences of successive normal-to-normal RR intervals greater than 50 ms among the total number of RR intervals (pNN50), higher MSNA frequency and higher MSNA incidence than controls. Therefore, this meta-analysis provides evidence that women with PCOS might show cardiovascular autonomic dysfunction, with reduced total and parasympathetic cardiac modulation, and increased sympathetic activity.

Effects of stroke on changes in heart rate variability during hemodialysis

Background

Stroke and low heart rate variability (HRV) are both associated with an unfavorable prognosis in hemodialysis patients. The relationship between stroke and changes in HRV during hemodialysis remains unclear.

Methods

This study measured differences between predialysis and postdialysis HRV (△HRV) in 182 maintenance hemodialysis patients, including 30 patients with stroke, to assess changes in HRV during hemodialysis, and also to compare results to 114 healthy controls.

Results

All predialysis HRV measurements had no differences between stroke patients and those without stroke, but were lower than healthy controls. Postdialysis very low frequency (VLF) (P < 0.001), low frequency (LF) (P = 0.001), total power (TP) (P < 0.001) and the LF/high frequency (HF) ratio (P < 0.001) increased significantly relative to predialysis values in patients without stroke, whereas postdialysis HRV did not increase in stroke patients. After multivariate adjustment, dialysis vintage was negatively associated with △VLF (β = -0.698, P = 0.046), △LF (β = -0.931, P = 0.009), and △TP (β = -0.887, P = 0.012) in patients without stroke. Serum intact parathyroid hormone (β = -0.707, P = 0.019) was negatively associated with △LF. Total cholesterol (β = -0.008, P = 0.001) and high sensitivity C-reactive protein (β = -0.474, P = 0.012) were inversely correlated with the △LF/HF ratio in patients without stroke.

Conclusion

HRV in hemodialysis patients is lower than in the general population. Increase in △HRV was observed in hemodialysis patients without stroke but not in stroke patients. This result suggests suppressed autonomic nervous reactions against volume unloading during hemodialysis, which might contribute to unfavorable outcomes in hemodialysis patients but even more so in those with prior stroke. Nephrologists should notice the importance of △HRV especially in high-risk patients.

Association of Diabetes Related Complications with Heart Rate Variability among a Diabetic Population in the UAE

Microvascular, macrovascular and neurological complications are the key causes of morbidity and mortality among type II diabetes mellitus (T2DM) patients. The aim of this study was to investigate the alterations of cardiac autonomic function of diabetic patients in relation to three types of diabetes-related complications. ECG recordings were collected and analyzed from 169 T2DM patients in supine position who were diagnosed with nephropathy (n = 55), peripheral neuropathy (n = 64) and retinopathy (n = 106) at two hospitals in the UAE. Comparison between combinations of patients with complications and a control diabetic group (CONT) with no complication (n = 34) was performed using time, frequency and multi-lag entropy measures of heart rate variability (HRV). The results show that these measures decreased significantly (p<0.05) depending on the presence and type of diabetic complications. Entropy, (median, 1st- 3rd interquartile range) for the group combining all complications (1.74,1.37-2.09) was significantly lower than the corresponding values for the CONT group (1.77, 1.39-2.24) with lag-1 for sequential beat-to-beat changes. Odds ratios (OR) from the entropy analysis further demonstrated a significantly higher association with the combination of retinopathy and peripheral neuropathy versus CONT (OR: 1.42 at lag 8) and an even OR for the combination of retinopathy and nephropathy (OR: 2.46 at lag 8) compared to the other groups with complications. Also, the OR of low frequency power to high frequency power ratio (LF/HF) showed a higher association with these diabetic-related complications compared to CONT, especially for the patient group combining all complications (OR: 4.92). This study confirms that the type of microvascular or peripheral neuropathy complication present in T2DM patients have different effects on heart rate entropy, implying disorders of multi-organ connectivity are directly associated with autonomic nervous system dysfunction. Clinical practice may benefit from including multi-lag entropy for cardiac rhythm analysis in conjunction with traditional screening methods in patients with diabetic complications to ensure better preventive and treatment outcomes in the Emirati Arab population.

Effects of high occupational physical activity, aging, and exercise on heart rate variability among male workers

Objectives

Effects of aging and leisure time physical activity (LPA) might influence the effect of occupational physical activity (OPA) on risk for cardiovascular disease (CVD). This study was conducted to determine whether OPA affects CVD after controlling the effects of LPA and other risk factors for CVD such as job stress.

Methods

Participants were 131 male Korean manual workers. Tests for heart rate variability (HRV) were conducted for five minutes in the morning at work. We defined OPA as the combined concept of relative heart rate ratio (RHR), evaluated using a heart rate monitor.

Results

Whereas high OPA was not related to any HRV items in the younger age group, high OPA was associated with an increased number of low-value cases among all HRV items in older workers. Exercise had beneficial effects only in the younger group. After controlling for exercise and other risk factors, the odds ratios of the root-mean square of the difference of successive normal R-R intervals (rMSSD) and high frequency band power (HF) among the older age and high OPA group compared with the younger age and low OPA group were 64.0 and 18.5, respectively. Social support and shift work were independent risk factors in HRV.

Conclusions

OPA in aging workers increases CVD risks. This study provides support for the need for protection of aging workers from physical work overload, and indicates the need for further study of optimal limits of OPA.

Cardiovascular autonomic tone relation to metabolic parameters and hsCRP in normoglycemia and prediabetes

AIMS

The aim of the study was to evaluate cardiovascular autonomic function (CAF) at different stages of obesity and in the presence of metabolic syndrome (MetS), and its association with metabolic parameters and hsCRP in subjects with normal glucose tolerance (NGT) and prediabetes.

METHODS

A total of 259 subjects (mean age 47.1 ± 14.6 years, mean BMI 31.4 ± 8.1 kg/m(2)), divided in 2 groups: NGT and prediabetes, and subdivided according to glucose tolerance, BMI and MetS, were enrolled. Anthropometric indices, glucose tolerance, blood pressure, serum lipids and hsCRP were measured. Body composition was estimated by impedance analysis. CAF was assessed by ANX-3.0 method.

RESULTS

Sympathetic and parasympathetic activity were decreased in severe obesity and MetS as compared to controls in NGT. Negative correlation was observed between sympathetic and parasympathetic tone and BMI, waist circumference, total body fat, visceral fat area (VFA), blood pressure, total and LDL cholesterol, and hsCRP in NGT; and VFA, HbA1c and glycemia in prediabetes.

CONCLUSION

Obesity and MetS seem to be associated with CAF deterioration, and metabolic parameters and hsCRP correlate with CAF and probably increase cardiovascular risk in NGT, whilst VFA, HbA1c and glycemia significantly influence CAF alterations in prediabetes.

Influence of polyunsaturated fatty acids on blood pressure, resting heart rate and heart rate variability among French Polynesians

OBJECTIVE

To analyze the associations between marine n-3 polyunsaturated fatty acids (PUFAs) and blood pressure (BP), resting heart rate (HR), and heart rate variability (HRV) in a population highly exposed to methylmercury through the diet.

METHODS

Concentrations of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) in erythrocytes membranes were measured in 180 French Polynesian adults (≥18 years) residing in Tubuai, which is a community with a traditional lifestyle, or Papeete, which has a modern lifestyle. HRV was measured using a 2-hour ambulatory electrocardiogram (Holter). Resting HR and BP were measured using standardized protocols and pulse pressure (PP) was calculated as systolic BP - diastolic BP. The associations between n-3 PUFAs and the dependent variables were studied using simple and multiple linear regressions.

RESULTS

Increasing DHA concentration was associated with lower resting HR (β = -2.57, p = 0.005) and diastolic BP (β = -1.96, p = 0.05) and higher HRV in multivariable models. Specifically, DHA was associated with high frequency (HF; β = 0.19, p = 0.02) and the square root of the mean squared differences of successive R-R intervals (difference between two consecutive R waves; rMSSD; β = 0.08, p = 0.03), which are specific indices of the parasympathetic activity of the autonomic nervous system.

CONCLUSION

DHA was associated with lower BP and resting HR and higher HRV among French Polynesians who are also exposed to high methylmercury levels.

Statins and the autonomic nervous system

Statins (3-hydroxy-3-methylglutaryl-CoA reductase inhibitors) reduce plasma cholesterol and improve endothelium-dependent vasodilation, inflammation and oxidative stress. A ‘pleiotropic’ property of statins receiving less attention is their effect on the autonomic nervous system. Increased central sympathetic outflow and diminished cardiac vagal tone are disturbances characteristic of a range of cardiovascular conditions for which statins are now prescribed routinely to reduce cardiovascular events: following myocardial infarction, and in hypertension, chronic kidney disease, heart failure and diabetes. The purpose of the present review is to synthesize contemporary evidence that statins can improve autonomic circulatory regulation. In experimental preparations, high-dose lipophilic statins have been shown to reduce adrenergic outflow by attenuating oxidative stress in central brain regions involved in sympathetic and parasympathetic discharge induction and modulation. In patients with hypertension, chronic kidney disease and heart failure, lipophilic statins, such as simvastatin or atorvastatin, have been shown to reduce MNSA (muscle sympathetic nerve activity) by 12–30%. Reports concerning the effect of statin therapy on HRV (heart rate variability) are less consistent. Because of their implications for BP (blood pressure) control, insulin sensitivity, arrhythmogenesis and sudden cardiac death, these autonomic nervous system actions should be considered additional mechanisms by which statins lower cardiovascular risk.

Heart rate variability today

Heart rate variability (HRV) non-invasively assesses the activity of the autonomic nervous system. During the past 30 years, an increasing number of studies have related the imbalance of the autonomic nervous system (as assessed by HRV) to several pathophysiogical conditions, particularly in the setting of cardiovascular disease. Sudden death, coronary artery disease, heart failure, or merely cardiovascular risk factors (smoking, diabetes, hyperlipidemia, and hypertension) are the best-known clinical circumstances that can affect and/or be affected by the autonomic nervous system. Analyses of HRV variables have been proposed as a component of the clinical evaluation for patient risk stratification due to its independent prognostic information. Yet the potential for HRV to be used widely in clinical practice remains to be established.

Association of heart rate variability with the framingham risk score in healthy adults

Background

The aim of this study was to investigate the relationship between heart rate variability (HRV), the Framingham risk score (FRS), and the 10-year risk of coronary heart disease (CHD) development among Korean adults.

Methods

The subjects were 85 healthy Korean adults recruited from a health check-up center. The FRS and 10-year risk of CHD development were calculated.

Results

The FRS in men was inversely correlated with the standard deviation of all normal to normal RR-intervals (SDNN); the root mean square successive difference (RMSSD); the percentage of successive normal cardiac inter-beat intervals greater than 20 ms, 30 ms, and 50 ms (pNN20, pNN30, pNN50); the low frequency (LF); and the high frequency (HF) (P < 0.05). There was no significant relationship between the FRS and HRV in women. Overall, in the receiver operating characteristic (ROC) analysis, the RMSSD, HF, SDNN, LF, LF/HF ratio, and pNN30 predicted an increased 10-year CHD risk. After adjusting for sex and body mass index, those with greater than one standard deviation in the RMSSD, HF, and LF had a 52-59% reduction in their 10-year risk of CHD development ≥ 10%.

Conclusion

This study therefore indicates that the HRV indices, particularly SDNN, RMSSD, pNN30, LF, and HF may be useful parameters for the assessment of CHD risk. Most notably, the usefulness of these HRV measures as indicators for CHD risk evaluation may be greater among men than among women.

Restless legs syndrome and conditions associated with metabolic dysregulation, sympathoadrenal dysfunction, and cardiovascular disease risk: a systematic review

Restless legs syndrome (RLS) is a distressing sleep and sensorimotor disorder that affects a large percentage of adults in the western industrialized world and is associated with profound reductions in quality of life. However, the etiology of RLS remains incompletely understood. Enhanced understanding regarding both the antecedents and sequelae of RLS could shed new light on the pathogenesis of RLS. Evidence from an emerging body of literature suggests associations between RLS and diabetes, hypertension, obesity, and related conditions linked to sympathetic activation and metabolic dysregulation, raising the possibility that these factors may likewise play a significant role in the development and progression of RLS, and could help explain the recently documented associations between RLS and subsequent cardiovascular disease. However, the relation between RLS and these chronic conditions has received relatively little attention to date, although potential implications for the pathogenesis and treatment of RLS could be considerable. In this paper, we systematically review the recently published literature regarding the association of RLS to cardiovascular disease and related risk factors characterized by sympathoadrenal and metabolic dysregulation, discuss potential underlying mechanisms, and outline some possible directions for future research.

Hypercholesterolemia magnitude increases sympathetic modulation and coagulation in LDLr knockout mice

We investigated the effects of low lipoprotein receptor deficiency in cholesterol blood concentrations, blood pressure, hemostatic factors, and the autonomic nervous system in three groups: control mice fed standard diet (CO, n=9), lipoprotein receptor-deficient mice (LDLr(-/-), n=9) fed standard diet (LDLr-S) or hypercholesterolemic diet (LDLr-H, n=8). Frequency domain analysis of heart rate and blood pressure variability was performed with an autoregressive algorithm. The spectral components were expressed in absolute (s(2) or mmHg(2)) and normalized units. Spontaneous baroreflex sensitivity (BRS) was estimated by alpha index, defined as square root ratio between low frequency power in blood pressure variability and heart rate variability. LDLr/- mice presented a significant increase in the cholesterol blood concentration (mean±SD; mg/dl; LDLr-S=202.01±34.38 and LDLr-H=530.7±75.17) compared to CO (79.2±13.6), p=0.001. The receptor deletion was associated with a heart rate variability reduction (p=0.013). The BRS was reduced (p<0.05) in LDLr-S and LDL-H (mean±SD: 0.96±0.39 and 0.59±0.34, respectively) compared to CO (4.02±1.92). Moreover, hypercholesterolemic diet significantly increased the cardiac sympathetic modulation (0V pattern of symbolic analysis: mean±SD, CO=8.04±4.53; LDLr-S=16.49±4.52 and LDLr-H=21.80±8.24, p=0.006). The 0V pattern was statically correlated to coagulation factor VII (r=0.555, p=0.0208). In LDLr-H, the concentration (interquartile range) of plasmatic fibrinogen and hemostatic factors VII (2.8-3.3) and XII (1.1-1.3) were increased compared to CO (0.9-1.1and 0.9-1.0, respectively) and LDLr-S (0.7-1.0 and 0.8-0.9, respectively) (p<0.004 for FVII and p<0.006 for FXII). Taken together, the results indicate that plasmatic cholesterol magnitude is determinant to increase the coagulation and the sympathetic modulation.

Heart rate variability and length of survival in hospice cancer patients

We examined the association between heart rate variability (HRV) and survival duration to evaluate the usefulness of HRV as a prognostic factor for hospice cancer patients. In terminally ill cancer patients who visited the Hospice clinic, we checked demographic data, Karnofsky performance scale (KPS), HRV, dyspnea, anorexia, as well as fasting blood glucose and total cholesterol. After following up their duration of survival, we examined meaningful prognostic factors for predicting life expectancy through the survival analysis. A total of 68 patients were included in final analysis. As KPS was lower, or when combined with dyspnea or anorexia, the survival duration was much shorter. HRV parameters except heart rate were all impaired in most patients. In particular, the group with mean heart rate of 100 or more beats per minute and the group with standard deviations of normal-to-normal R-R intervals (SDNN) of 21.3 ms (75 percentile) or less showed significantly shorter survival duration. The final multivariate analysis adjusting for age, gender, fasting blood glucose, and total cholesterol showed that KPS, dyspnea, anorexia, and SDNN were significant prognostic factors in survival duration. For the first time, we report that SDNN is a prognostic factor in terminal cancer patients.

The relationship of autonomic imbalance, heart rate variability and cardiovascular disease risk factors

Cardiovascular disease (CVD) is the leading cause of death and disability worldwide. The understanding of the risk factors for CVD may yield important insights into the prevention, etiology, course, and treatment of this major public health concern. Autonomic imbalance, characterized by a hyperactive sympathetic system and a hypoactive parasympathetic system, is associated with various pathological conditions. Over time, excessive energy demands on the system can lead to premature aging and diseases. Therefore, autonomic imbalance may be a final common pathway to increased morbidity and mortality from a host of conditions and diseases, including cardiovascular disease. Heart rate variability (HRV) may be used to assess autonomic imbalances, diseases and mortality. Parasympathetic activity and HRV have been associated with a wide range of conditions including CVD. Here we review the evidence linking HRV to established and emerging modifiable and non-modifiable CVD risk factors such as hypertension, obesity, family history and work stress. Substantial evidence exists to support the notion that decreased HRV precedes the development of a number of risk factors and that lowering risk profiles is associated with increased HRV. We close with a suggestion that a model of autonomic imbalance may provide a unifying framework within which to investigate the impact of risk factors, including psychosocial factors and work stress, on cardiovascular disease.

Early impairment of left ventricular function in hypercholesterolemia and its reversibility after short term treatment with rosuvastatin

BACKGROUND

Hypercholesterolemia contributes to coronary heart disease but little is known about its direct effect on myocardial function. We evaluated left ventricular function using echocardiography and the effect of treatment with rosuvastatin in a group of patients with primary hypercholesterolemia.

METHODS AND RESULTS

Thirty-three patients with primary hypercholesterolemia (HC) and without evidence of coronary heart disease and 25 aged matched healthy volunteers (C) were submitted to conventional echocardiography, pulsed wave tissue Doppler imaging (PWTDI), color Doppler myocardial imaging (CDMI) and integrated backscatter (IBS). Echocardiographic evaluation was repeated after 6 months of treatment with rosuvastatin (10mg/day) in 17 patients. Compared with C, patients with HC showed lower E/A ratio (p<0.0001) and higher Tei index mit (p<0.0001), as well as lower PW TDI E/A both at septum (p<0.0001) and at lateral level (p<0.0001) and higher modified Tei index both at septal annulus (p<0.0001) and lateral annulus (p<0.0001). Integrated backscatter parameters were significantly reduced in patients with HC (CVIsept p<0.0001 and CVI post wall p<0.05). CDMI derived indices in the two groups were not different. After 6 months of Rosuvastatin treatment a significant reduction of LDL cholesterol levels (51%, p<0.0001) was registered in HC patients together with a significant improvement of longitudinal global systolic and diastolic function (Tei index) and myocardial intrinsic contractility (CVI).

CONCLUSIONS

These data suggest that in patients with hypercholesterolemia exists an early cardiomyopathy characterized by systolic and diastolic dysfunction. That could produce a substratum for an "impaired preconditioning". Rosuvastatin seems able to revert systolic abnormalities.

Lipid-lowering therapy with statins, a new approach to antiarrhythmic therapy

Inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase (statins) are the most effective and best-tolerated drugs to treat elevated levels of low-density lipoprotein cholesterol (LDL-C). In addition, they exhibit other effects unrelated to their lipid lowering effects (pleiotropic actions). In recent years, experimental and clinical evidence demonstrates that statins exert antiarrhythmic properties, reducing the recurrences of supraventricular and life-threatening ventricular arrhythmias both in patients with and without coronary artery disease (CAD). Thus, statins may constitute a novel therapeutic approach to cardiac arrhythmias. This article reviews the antiarrhythmic properties of statins as well as the possible mechanisms involved, including the lowering of LDL-C levels, the improvement of endothelial dysfunction and autonomic function, the stabilization of the atherosclerotic plaques, the antioxidant, antiinflammatory, antithrombotic and cardioprotective properties and the modulation of transmembrane ion fluxes.

The role of vagal function in the risk for cardiovascular disease and mortality

Cardiovascular disease (CVD) is the leading cause of death and disability worldwide. The understanding of the risk factors for CVD may yield important insights into the prevention, etiology, course, and treatment of this major public health concern. We review the evidence for the role of vagal function in the risk for cardiovascular disease and mortality. Using a broad range of indicators of vagal function including resting heart rate, heart rate recovery, heart rate variability, and baroreflex sensitivity we show that decreased vagal function is associated with an increased risk for morbidity and mortality. These effects are independent of traditional risk factors. Moreover, we show that decreased vagal function is associated with both traditional and emerging risk factors as well as modifiable and non-modifiable risk factors. Most importantly, we provide evidence to support the notion that decreased vagal function precedes the development of a number of risk factors and that modification of risk profiles in the direction of lower risk is associated with increased vagal function. We close with a brief overview of the neural concomitants of vagal function and suggest that a model of neurovisceral integration may provide a unifying framework within which to investigate the impact of risk factors, including psychosocial factors, on cardiovascular disease.

Heart rate variability in an ageing population and its association with lifestyle and cardiovascular risk factors: results of the SAPALDIA study

AIMS

(i) To report associations between cardiovascular risk factors and heart rate variability (HRV) in a general population and (ii) to provide normal values for various HRV measurements in a healthy European general population sample aged >or=50.

METHODS AND RESULTS

Twenty-four-hour electrocardiograms were recorded in 1742 randomly selected SAPALDIA (Swiss cohort study on Air Pollution and Lung Diseases in Adults) participants aged >or=50. In multivariate regression analyses, women (n=895) had a 6.1% lower standard deviation of all normal RR (NN) intervals (SDNN), a 11.4% lower total power (TP), and a 27.2% lower low-frequency (LF) power than men (n=847). Per unit increase in BMI, SDNN decreased by 0.7% and TP decreased by 1.2%. Persons with high blood pressure had a 9.2% lower LF than normotensive persons and current smokers a 15.5% lower LF than never smokers. Each hour of heavy physical exercise was associated with a 2.0% increase in SDNN, a 3.6% increase in the high frequency (HF) range power and a 4.2% increase in LF power. Higher levels of uric acid, high-sensitive C-reactive protein and non-HDL-cholesterol were associated with lower TP, HF and LF. Percentiles of TP and LF/HF as a function of age were calculated for an asymptomatic subsample of participants (n=499) free of cardioactive medications.

CONCLUSION

Heart rate variability in a general population sample shows expected associations with all known cardiovascular risk factors, although not identically for all HRV domains. Together with our percentile estimates for HRV as a function of age, these findings could assist scientists in interpreting 24 h HRV values and factors influencing them in an ageing population.

The effect of atorvastatin on heart rate variability and lipoproteins in patients treated with coronary bypass surgery

Statins reduce mortality in patients with coronary heart disease (CHD). An antiarrhythmic effect of statins has been suggested and reported as a possible contributing mechanism. The aim of this study was to examine whether atorvastatin had any effect on heart rate variability (HRV), an important predictor of sudden cardiac death. Eighty patients previously treated with coronary artery bypass grafting (CABG) were studied. The study was designed as a randomized, placebo-controlled, double blinded crossover study. The patients were randomized in two groups, and were treated with 80 mg atorvastatin or placebo for 6 weeks before crossing over to the opposite treatment for another 6 weeks. There was no washout between treatments. Twenty-four-hour Holter recording and plasma lipids and lipoprotein measurements were performed at baseline and after each 6-week period. There was no change in HRV indices after treatment with 80 mg atorvastatin for 6 weeks. A significant reduction in total cholesterol (46%, p</=0.001), LDL cholesterol (61%, p</=0.001) and triglycerides (35%, p</=0.001) were observed during treatment with atorvastatin. Therapy with 80 mg atorvastatin daily for 6 weeks reduced total cholesterol, LDL cholesterol and triglycerides significantly, while there was no effect on 24-h HRV indices. The study therefore does not lend support for any effect of atorvastatin on HRV after 6 weeks of treatment in patients treated with CABG.

Statins, Ventricular Arrhythmias and Heart Rate Variability in Patients with Implantable Cardioverter Defibrillators and Coronary Heart Disease

The aim of this study was to evaluate whether the incidence of ventricular arrhythmias and heart rate variability were influenced by statin treatment and lipid levels in patients treated with an implantable cardioverter defibrillator (ICD). Heart rate variability measurements were performed in 86 patients with coronary heart disease and an ICD implant. The number of events with ventricular fibrillation and ventricular tachycardia were recorded during a 12-month period. This study lends little support for an antiarrhythmic effect of statins or any relation between plasma lipids and lipoproteins and malignant ventricular arrhythmias in patients with an ICD.

A prospective evaluation of the effect of simvastatin on heart rate variability in non-ischemic cardiomyopathy

BACKGROUND

Modulation of sympathetic tone may contribute to statin-mediated reduction in sudden cardiac death. We examined the effect of simvastatin on heart rate variability (HRV) in patients with non-ischemic dilated cardiomyopathy to evaluate for an antisympathetic effect of statins independent of anti-ischemic properties.

METHODS

The study was a prospective, open-label, self-controlled trial. Frequency domain analysis of HRV was assessed in 25 patients with non-ischemic dilated cardiomyopathy at baseline and after a 6-week course of simvastatin. The primary end point was the change in 5-minute sitting total spectral power (TSP) as a composite measurement of autonomic nervous system modulation. Secondary end points included the change in respiratory frequency area (RFa) with deep breathing (parasympathetic stress) and in low-frequency area (LFa) with Valsalva (sympathetic stress).

RESULTS

Simvastatin had no effect on 5-minute sitting TSP (baseline 1932 +/- 1165 vs posttreatment 2570 +/- 1877 square milliseconds, P = .770), RFa with deep breathing (baseline 19 +/- 7 vs posttreatment 14 +/- 4 [beat/min]2, P = .31), or LFa with Valsalva (baseline 26 +/- 6 vs posttreatment 32 +/- 8 [beat/min]2, P = .342). Bivariate analysis demonstrated no correlation between low-density lipoprotein (LDL) change and change in TSP or RFa, but did demonstrate an inverse relationship between change in LDL and change in LFa with Valsalva stress (r = -0.45 and P = .041).

CONCLUSION

Although simvastatin did not change baseline HRV, a modest relationship exists between the extent of LDL reduction and sympathetic responsiveness to stress.

Effect of atorvastatin and fenofibrate on autonomic tone in subjects with combined hyperlipidemia

This randomized open-label trial investigated whether autonomic cardiovascular control is altered in middle-aged men with combined hyperlipidemia and whether such alterations are affected by short-term, lipid-lowering therapy with atorvastatin and/or fenofibrate. Compared with normolipidemic subjects, untreated subjects with combined hyperlipidemia had several abnormalities of autonomic tone, indicating increased sympathetic tone and decreased baroreflex sensitivity. The alterations in autonomic cardiovascular control were partially reversible by each of the lipid-lowering drugs.

HMG-CoA reductase inhibitors improve heart rate variability in patients with a previous myocardial infarction

Statins decrease mortality in patients with coronary heart disease (CHD). The effect may begin early after initiation of therapy, but the mechanism(s) behind this has not been totally delineated. In the present study 304 patients referred for elective coronary angiography due to suspected CHD were included. Seventy-three of the patients had a previous myocardial infarction (MI). Twenty-four hours heart rate variability (HRV) was obtained in all the patients. In patients with a previous MI, HRV was significantly higher in patients who were treated with statins compared to patients not given statins. Matching of the patients with identical serum cholesterol levels (3.7 mmol l(-1) < or = s-cholesterol < or = 8.1 mmol l (-1)) also revealed a higher SDNN in patients who had a previous MI and were on statin treatment. Similar results were seen by matching for serum low-density-lipoprotein cholesterol levels. In line with this, step-wise multiple linear regression analysis revealed that treatment with statins had an independent and significant impact on HRV. Our data suggest that statins may increase HRV in patients with a previous MI, which could in part explain the early beneficial effect on clinical events observed in several trials.