Abstract
Kamikawa S et al. Clin Cardiol. 2013;36:394–400
To the Editor:
We read with great interest the article by Kamikawa et al1 titled “Reduced Diurnal Variation of Heart Rate Is Associated With Increased Plasma B‐Type Natriuretic Peptide Level in Patients With Atrial Fibrillation,” which was recently published in Clinical Cardiology.
The authors aimed to show the association between the plasma B‐type natriuretic peptide (BNP) level and heart rate variation in patients with atrial fibrillation (AF). Multiple linear regression analysis revealed that the heart rate variation was an independent factor related to the BNP level in patients with AF. In this context, the authors concluded that the reduced diurnal variation of heart rate was significantly associated with increased BNP, which is linked to left ventricular (LV) diastolic dysfunction in patients with AF. The current study is well designed and gives detailed information, but we have some comments about the article.
It is reported that the tissue of the left atrial appendage (LAA) in patients with valvular AF showed significant pathological changes, which are well known to enhance BNP production in the ventricular myocardium.2, 3 Contrary to earlier theories that LV myocardium is the main source of BNP, it has recently been shown that BNP is mainly secreted from the left atrium in patients with AF.4 LAA seems to be a source for BNP, as it represents an overload sensor of the heart.5
Furthermore, the plasma BNP concentration is an independent negative predictor for the LAA peak flow velocity and serves as a determinant of LAA function in nonvalvular AF.6 In addition, Kim et al showed that the duration of AF is an independent predictor of plasma BNP levels in patients with chronic AF and preserved LV systolic function, due to the influence on the LAA peak flow velocity.7
In conclusion, LV dysfunction is a determinant of LAA function and therefore increases BNP levels.6 In addition to LV dysfunction, increased plasma BNP levels could be related to rapid progression of LAA dysfunction in patients with AF.6 Transesophageal echocardiography can be used to identify relationships between LAA peak flow velocities, duration of AF, and plasma BNP levels.8, 9 If relationships between LAA peak flow velocities, duration of AF, and plasma BNP levels were identified, potential mechanisms in the relationship of heart rate variation and LV dysfunction to BNP levels could have been evaluated more precisely.
Emre Yalcinkaya, MD Murat Celik, MD Erkan Yildirim, MD Salim Yasar, MD Department of Cardiology Gulhane Military Medical Faculty Ankara, Turkey Baris Bugan, MD Department of Cardiology Malatya Army Hospital Malatya, Turkey
References
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