Evaluation of plasma brain natriuretic peptid levels in patients with isolated left bundle branch block and preserved left ventricular systolic function

Abstract

Introduction and aim: According to our knowledge, no clinical research on plasma brain natriuretic peptid (BNP) levels in patients with isolated left bundle branch block (LBBB) and in the range of plasma BNP level of normal population is found. We studied the effect of isolated LBBB on plasma BNP levels in patients with isolated LBBB and preserved left ventricular (LV) systolic function having no signs of heart failure according to the clinical and biochemical criteria. Method: This study was carried out by measuring plasma BNP levels in the patients who were diagnosed with isolated LBBB and normal LV ejection fraction (LVEF) and had normal coronary angiography. Total 8432 patients who applied to our clinic with various reasons were screened and 378 patients with LBBB were detected. People who are higher increases than in the range of plasma BNP level of normal population (0-100 pg/mL) were excluded from this study. Finally 42 patients with isolated LBBB who met inclusion and exclusion criteria. Additionally, 30 healthy people with normal ECG and echocardiography were included in the study. All subjects (n=72) were classified in according to the median value of the plasma BNP levels as low BNP group (BNP≤14.6 pg/mL) and high BNP group (BNP>14.6 pg/mL). Results: Mean plasma BNP level was higher in isolated LBBB group than in the control group (30.16±22.04 pg/mL vs 15.81±14.24 pg/mL, p=0.003). LVEF was lower in isolated LBBB group than in the control group (58.1±4.3% vs 62.6±4.9%, p=0,001). Acording to the control group, left atrial diameter and interventricular septal thickness increased in isolated LBBB (p<0.05, p<0.01 respectively). Plasma BNP levels showed a significantly positive correlation with age (r:0.35, p=0.002) and QRS duration (r:0.39, p=0.001). Logistic regression analysis showed that isolated LBBB (OR, 3.91 [95% CI,1.08 - 14.16], p= 0.038) and age (OR, 1.10 [95% CI,1.04 - 1.16], p= 0.001) independently effect plasma BNP level. Conclusion: This study shows that plasma BNP level increases in patients with isolated LBBB and preserved LV systolic function. Determining plasma BNP levels in asymptomatic individuals with isolated LBBB can contribute to the pre-detection of subclinical LV dysfunctions also in the range of plasma BNP level of normal population.