The relationship between BNP, diastolic parameters and heart rate in patients with persistant atrial fibrillation

Introduction: There are few trials showing that strict rate control is superior to lenient rate control in patients with chronic atrial fibrillation. Chronic atrial fibrillation is frequently accompanied by diastolic dysfunction. Subjects with atrial fibrillation, serum BNP values are higher than subjects with sinus rhytm. High BNP values are related to diastolic dysfunction. Our study aims to investigate the effect of strict rate control on BNP values and improvement in diastolic dysfunction in patients with chronic atrial fibrillation.Materials and method: 38 patients who admitted to cardiology outpatient clinic between 01 october 2009- 01 september 2011 and had chronic atrial fibrillation treated with strict rate control strategy are included in our study. Serum BNP values, echocardiography, electrocardiography, 24 hour ambulatory electrocardiography recordings are examined to compare clinical and laboratory features of 25 patients who had strict rate control ( mean heart rate ? 80 beats /min) and 13 patients in whom strict rate control could not be achieved ( mean heart rate > 80 beats /min).Findings: Patients with strict rate control had mean heart rate 101±16,3 beats /min initially and 77±5,2 after strict rate control. The change in mean heart rate was statististically significant ( p< 0.001). Initial mean BNP value was 392±272 pg/dl and 249±224 pg/dl after strict rate control. The difference in mean BNP values was statistically significant (p<0.001). Mean LVESV was 59±8,9 ml before strict rate control and 57,8±9,4 after strict rate control, the change in end sistolic volume was statistically significant (p:0.017). Also mean LVEDV was 119,7±19,7 ml before strict rate control and 116±18 ml after strict rate control, the change in end diastolic volume was statistically significant (p<0,001). Mean LA area was 30,7±7,4 cm2 before strict rate control and 29,8±7,3 cm2 after strict rate control. The change in mean LA area was statistically significant (p:0,004). Mean RA area was 23,4±5,6 cm2 before strict rate control and 22,6±5,4 cm2 after strict rate control. Teh difference in RA area was statistically significant(p:<0,001). No significant change in diastolic parameters was observed. In patients with strict rate control, change in serum BNP values showed moderately positive correlation with mean heart rate (p:0,008, r:0,515). Changes in BNP values and LA area showed statistically significant moderate correlation (p:0,015, r:0,481).In patients with lenient heart rate control initial mean BNP value was 265±142.6 pg/dl and follow up mean value was 389,5±191,5 pg/dl. BNP values rose during follow up in tehse patients and this change was statistically significant (p:0.01). Mean heart rate did not change significantly during follow up. (94,6±6,8 beats/min; 94,2±5,9 beats/min; p: 0,697). Mean heart rate during activity significantly decreased compared to initial mean heart rate (123,2±13,7 beats/min, 110,8±17,9 beats/min; p: 0.005). no such relationship was observed for meaan resting heart rate (76,1±4,3 beats/min, 77,1±3,7 beats/min; p:0.516). As a result statistically significant decreases in mean BNP values and mean LVEDV, RVEDA, LA area and RA area were observed in patients with strict heart rate control. There was no significant change of thes parameters in patients without strict heart rate control.Sonuç: With strict rate control no improvement in diastolic parameters but positive changes in volumes of heart chambers were observed in patients with chronic atrial fibrillation. Also serum BNP values significantly decreased with strict heart rate control. We conclude that strict heart rate control has positive effects on structural changes of heart.Keywords: atrial fibrillation, strict heart rate control, lenient heart rate control, diastolic dysfunction, BNP