Heart rate, heart rate variability and inflammatory biomarkers among young and healthy adults.

BACKGROUND: Heart rate (HR), heart rate variability (HRV), and inflammation are all associated with cardiovascular morbidity and mortality. The aim of this study was to assess potential interrelationships between these parameters in a young and healthy population. METHODS: Healthy individuals aged 25-41 years were included in a prospective population-based study. All participants underwent 24-h electrocardiography using a validated device. The standard deviation of all normal RR intervals (SDNN) was pre-defined as the main HRV outcome variable. High-sensitivity C-reactive protein (hs-CRP), total leukocyte (LC) count and LC subtypes were obtained from venous blood samples. RESULTS: A total of 2064 participants (47% men, 37 years) were included in this analysis. In multivariable linear regression analyses using SDNN as the outcome variable, ß-coefficients (95% confidence intervals) per 1 standard deviation (SD) increase on the log-scale were -0.11 (-0.16; -0.07), p < .0001 for hs-CRP, -0.13 (-0.17; -0.09), p < .0001 for total LC count, -0.12 (-0.16; -0.08), p < .0001 for neutrophils, -0.04 (-0.09; 0.00), p = .05 for lymphocytes and -0.08 (-0.09; -0.02), p = .005 for monocytes. There were positive relationships between resting and ambulatory HR and inflammatory biomarkers, except for lymphocytes. CONCLUSION: In this large cohort of young and healthy adults, inflammatory parameters were strongly associated with increased HR and decreased HRV, suggesting an important interaction between inflammatory pathways and the autonomic nervous system. Key message Inflammatory biomarkers, such as high-sensitivity C-reactive protein and leukocyte cell count with its subtypes were inversely associated with HRV and positively associated with HR. Our findings suggest important interrelationships between inflammatory pathways and the ANS.

Determinants of Left Atrial Volume in Patients with Atrial Fibrillation.

INTRODUCTION: Left atrial (LA) enlargement is an important risk factor for incident stroke and a key determinant for the success of rhythm control strategies in patients with atrial fibrillation (AF). However, factors associated with LA volume in AF patients remain poorly understood. METHODS: Patients with paroxysmal or persistent AF were enrolled in this study. Real time 3-D echocardiography was performed in all participants and analyzed offline in a standardized manner. We performed stepwise backward linear regression analyses using a broad set of clinical parameters to determine independent correlates for 3-D LA volume. RESULTS: We included 210 patients (70.9% male, mean age 61±11years). Paroxysmal and persistent AF were present in 95 (45%) and 115 (55%) patients, respectively. Overall, 115 (55%) had hypertension, 11 (5%) had diabetes, and 18 (9%) had ischemic heart disease. Mean indexed LA volume was 36±12ml/m2. In multivariable models, significant associations were found for female sex (ß coefficient -10.51 (95% confidence interval (CI) -17.85;-3.16), p = 0.0053), undergoing cardioversion (ß 11.95 (CI 5.15; 18.74), p = 0.0006), diabetes (ß 14.23 (CI 2.36; 26.10), p = 0.019), body surface area (BSA) (ß 34.21 (CI 19.30; 49.12), p<0.0001), glomerular filtration rate (ß -0.21 (CI -0.36; -0.06), p = 0.0064) and plasma levels of NT-pro brain natriuretic peptide (NT-proBNP) (ß 6.79 (CI 4.05; 9.52), p<0.0001), but not age (p = 0.59) or hypertension (p = 0.42). Our final model explained 52% of the LA volume variability. CONCLUSIONS: In patients with AF, the most important correlates with LA volume are sex, BSA, diabetes, renal function and NT-proBNP, but not age or hypertension. These results may help to refine rhythm control strategies in AF patients.