Atrial fibrillation is a common complication in the clinical course of arterial hypertension. Many efforts have been made to identify factors that might predict the risk of atrial fibrillation in this setting. We hypothesized that RDW (red cell distribution width, a marker recently associated with cardiovascular disorders) and plasma uric acid (a marker of oxidative stress) could be such factors.Design and method:
We compared a group of 123 consecutive patients in sinus rhythm with a group of 135 consecutive patients in atrial fibrillation, either permanent (102 patients) or paroxysmal (33 patients). All patients had been diagnosed with arterial hypertension for at least 5 years. We recorded demographic data, case history, clinical examination and blood test results (complete blood count with RDW measurement, plasma uric acid, thyroid function tests and blood analyses indicated by the standard of care in hypertensive and atrial fibrillation patients). Subjects with hemoglobin levels under 11 g/dl were excluded from the study. Transthoracic echocardiography has also been performed in every patient. Data were analyzed using SPSS 19.0.Results:
Plasma uric acid levels were significantly different between patients with paroxysmal AF (5.8 ± 1.6 mg/dl), permanent AF (6.7 ± 2.6 mg/dl), and patients without AF (5.3 ± 1.8 mg/dl) (p < 0.001). RDW levels were similar between patients with paroxysmal AF (12.5 ± 1.1%) and patients without AF (12.5 ± 1.1%), while being significantly higher in patients with permanent AF (13.5 ± 1.9%) (p < 0.001). Thyroid function tests were not different between groups. Echocardiographic parameters of cardiac remodeling (left atrium transverse diameter and volume, left ventricular end-diastolic diameter, posterior wall and septal thickness, right atrial and right ventricular diameter) had higher values in atrial fibrillation group (p < 0.001 for all).Conclusions:
There is an association between high levels of plasma uric acid and AF in hypertensive patients. Increased RDW values are associated with permanent AF, but not with paroxysmal AF. Further studies are needed in order to better evaluate these relationships and to establish whether these markers could be used in the prediction of atrial fibrillation in hypertensive patient.