Cardiac autonomic function and cognitive performance in patients with atrial fibrillation

Heart rate variability and stroke or systemic embolism in patients with atrial fibrillation

BACKGROUND

Stroke remains one of the most serious complications in atrial fibrillation (AF) patients and has been linked to disturbances of the autonomic nervous system.

OBJECTIVE

We hypothesized that impaired cardiac autonomic function might be associated with an enhanced stroke risk in AF patients.

METHODS

We enrolled 1922 AF patients who were either in sinus rhythm (SR-group, n=1121) or AF (AF-group, n=801) on a 5-minute resting ECG recording. HRV triangular index (HRVI), standard deviation of normal-to-normal intervals, root mean square root of successive differences of normal-to-normal intervals, mean heart rate, 5-min total power and power in the high frequency, low frequency and very low frequency range were calculated. We constructed Cox regression models to examine the association of HRV parameters with the composite endpoint of stroke or systemic embolism.

RESULTS

Mean age was 71±8 years in the SR group and 75±8 in the AF group. 37 patients in the SR group (3.4%) and 60 patients in the AF group (8.0%) experienced a stroke or systemic embolism during a follow-up time of 5 years. In patients with SR, HRVI <15 was the strongest HRV parameter to be associated with stroke or systemic embolism (hazard ratio 3.04; 95% confidence interval 1.3-7.0; p=0.009) after adjustment for multiple confounders. In the AF group, we found no HRV parameter to be associated with the composite endpoint.

CONCLUSION

HRVI measured during SR on a single 5-minute ECG recording is independently associated with stroke or systemic embolism in AF patients. HRV analysis in SR may help to improve risk stratification in AF patients.

Atrial fibrillation and preexisting cognitive impairment in ischemic stroke patients: Dijon Stroke Registry

BACKGROUND

Atrial Fibrillation (AF) is a common cause of ischemic stroke (IS), and is associated with cognitive impairment in the general population. We aimed to compare the prevalence of preexisting cognitive impairment between IS patients with and without AF, and to assess whether prior brain damage could contribute to the observed differences.

METHODS

Patients with acute IS were prospectively identified from the population-based Dijon Stroke Registry, France. Patients who had a CT-scan as brain imaging modality were included in this analysis to assess the presence of preexisting leukoaraiosis, old vascular brain lesions, and cerebral atrophy. Characteristics of patients including prior-to-stroke cognitive status (normal cognition, mild cognitive impairment (MCI), or dementia) were compared between those with and without AF.

RESULTS

Among 916 IS patients, 288 (31.4 %) had AF, of whom 88 had newly diagnosed AF. AF patients had more frequent prior MCI (17.8 % versus 10.2 %) or dementia (22.4 % versus 13.1 %) (p = 0.001), vascular risk factors, and preexisting brain damage. In unadjusted model, preexisting cognitive impairment was associated with AF (OR=2.24; 95 % CI: 1.49-3.37, p < 0.001 for MCI; OR=2.20; 95 % CI: 1.52-3.18, p < 0.001 for dementia). After adjustment for clinical and imaging variables, preexisting mild cognitive impairment (OR=1.87; 95 % CI: 1.06-3.32, p = 0.032) and dementia (OR=1.98; 95 % CI: 1.15-3.40, p = 0.013) were independently associated with AF.

CONCLUSION

AF is a common condition in IS patients and is associated with preexisting cognitive impairment. Brain lesions visible on imaging did not seem to fully account for this association that may involve other mechanisms yet to be elucidated.

Associations between Autonomic Function and Cognitive Performance among Patients with Cerebral Small Vessel Disease

Data linking heart rate variability (HRV) and cognitive status remains controversial and scarce, particularly in cerebral small vessel disease (CSVD) patients. Whether the association between HRV and cognitive performance exists in CSVD patients is unclear. Hence, we aimed to investigate the association between HRV and cognitive performance in patients with CSVD. This cross-sectional study was conducted among 117 CSVD patients. All patients underwent HRV assessment and global cognitive evaluation by the Mini-Mental-State Examination (MMSE) and Montreal Cognitive Assessment (MoCA). Multivariable analyses were performed to evaluate the association between HRV and cognitive status. The mean age of study population was 59.5 ± 11.8 years and 39.3% were female. After adjusting for confounding factors, a higher high frequency (HF) norm was independently associated with better MMSE scores (β = 0.051; 95% confidence interval (CI): 0.012~0.090; p = 0.011) and MoCA scores (β = 0.061; 95% CI: 0.017~0.105; p = 0.007), while a higher low frequency (LF)/HF ratio was independently associated with worse MMSE scores (β = -0.492; 95% CI: -0.893~-0.092; p = 0.017) and MoCA scores (β = -0.691; 95% CI: -1.134~-0.248; p = 0.003). The HF norm was positively associated with global cognitive performance, whereas the LF/HF ratio was negatively associated with global cognitive performance among CSVD patients. Further study of the relationship between autonomic function and cognitive performance is warranted.

Overnight pulse rate variability and risk of major neurocognitive disorder in older patients with obstructive sleep apnea

BACKGROUND

Increasing evidence links obstructive sleep apnea (OSA) to cognitive decline. Autonomic dysfunction assessed by heart rate variability is a promising early biomarker of cognitive impairment in populations without major neurocognitive disorder (MND). We aimed to determine whether nocturnal pulse rate variability (PRV) extracted from oximetry signal and OSA severity could predict MND onset among older OSA patients.

METHODS

This study relied on data collected within the multicenter longitudinal Pays de la Loire Sleep Cohort, linked to health administrative data to identify new-onset MND. We included patients ≥60 years with newly diagnosed OSA, and no history of MND or atrial fibrillation. Cox proportional-hazards models were used to evaluate the association of MND with indices of PRV and OSA severity generated from sleep recordings.

RESULTS

After a median follow-up of 6.8 [4.7-9.4] years, 70 of 3283 patients (2.1%) had been diagnosed with MND. In multivariable Cox models, MND incidence was associated with age (p < 0.0001), depression (p = 0.013), and PRV assessed by the root mean square of the successive normal-to-normal (NN) beat interval differences (RMSSD; p = 0.008) and standard deviation of NN beat intervals (SDNN; p = 0.02). Patients with the highest quartile of RMSSD had a 2.3-fold [95%CI 1.11-4.92] higher risk of being diagnosed with MND. Indices of OSA and nocturnal hypoxia severity were not associated with MND.

CONCLUSIONS

Within a large clinic-based cohort of older patients with OSA, we found an association between oximetry-based indices of PRV and the onset of MND. Nocturnal oximetry-derived PRV indices could allow the early identification of OSA patients at higher risk of MND.