Reduced Diurnal Variation of Heart Rate is Associated With Increased Plasma B‐Type Natriuretic Peptide Level in Patients With Atrial Fibrillation

Background The plasma B‐type natriuretic peptide ( BNP ) level has been shown to be increased in patients with chronic atrial fibrillation ( AF ) independent of left ventricular ejection fraction ( LVEF ). The purpose of this study is to evaluate the relationship between the plasma BNP level and heart rate variation in patients with AF . Hypothesis The plasma BNP level is associated with heart rate variation in patients with AF. Methods A total of 102 patients with AF and preserved LVEF were included from 2 hospitals. The ambulatory electrocardiographic recording and measurement of plasma BNP levels were performed simultaneously. Echo‐Doppler parameters were measured as the average of 10 consecutive cardiac cycles. Results A difference in the mean heart rate between night and day ( DIFF ) and the standard deviation of the 5‐miniute mean R‐R interval ( SDARR ) were significantly associated with log‐transformed BNP levels ( r = −0.411, P < 0.001 and r = −0.243, P = 0.049, respectively). In echocardiography, the ratio of E velocity to early diastolic velocity, which reflects left ventricular ( LV ) filling pressure, was significantly correlated with the DIFF and SDARR , along with the log‐transformed BNP level. Stepwise multiple linear regression analysis revealed that the DIFF and age were independent factors related with the BNP level ( P < 0.01). Conclusions The reduced diurnal variation of heart rate was significantly associated with increased BNP , which is linked to LV diastolic dysfunction in patients with AF .