Brain natriuretic peptide and P wave duration in dialysis patients

P wave duration and dispersion, defined as the difference between the maximum and minimum P duration, are regarded as very important non-invasive ECG markers for assessing atrial arrhythmia risk. Plasma brain natriuretic peptide (BNP) level is an independent predictor of recurrence of atrial fibrillation. We compared the effects of hemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD) on P wave duration, P dispersion, and BNP in end-stage renal disease (ESRD) patients and examined the relationship between BNP levels, P wave duration, and P dispersion.

Age-matched 22 HD patients (mean age 52.3 +/- 14.0 years) and 19 CAPD patients (mean age 46.7 +/- 10.9 years) were studied.

BNP levels were greater in HD patients before the HD session (459.0 +/- 465.1 pg mL(-1)) than in CAPD patients (139.0 +/- 170.1 pg mL(-1)). The maximum and minimum P duration, and P dispersion, were similar for both groups (P > 0.05). Whereas BNP levels were negatively related to minimum P duration (r = -0.518, P = 0.019), BNP levels were positively correlated with systolic blood pressure and diastolic blood pressure (r = 0.672, P = 0.001 and r = 0.497, P = 0.022, respectively) in HD patients.

Whereas BNP levels are higher in HD patients when they are at peak-volume status, just before HD, P wave duration and P dispersion were similar for both groups. A negative relationship was detected between BNP levels and minimum P duration in HD patients. Expansion of extra-cellular volume causing myocardial stretching may be the principal cause of increased BNP in HD patients. A functional relationship between BNP and the P wave was not found. Additional studies are needed to evaluate the effect of BNP on the P wave.