Utility of N-terminal pro-brain natriuretic peptide in detecting diastolic dysfunction in asymptomatic hypertensive patients: comparison with echocardiography.

Introduction: Data suggest that brain natriuretic peptide (BNP) and NT pro-BNP partially reflect ventricular pressure and could have a role in the early detection of diastolic abnormalities in hypertensive patients with normal systolic function. This study aimed to assess the role of NT pro-BNP for early detection of diastolic dysfunction in patients with hypertension and to correlate its level with echocardiographic parameters of diastolic dysfunction. Methods: This is a comparative cross-sectional study. Hundred cases of asymptomatic hypertensive patients with normal left ventricular (LV) systolic function and 100 healthy subjects were subjected to echocardiography and measurement of serum NT-pro BNP who received care at outpatient department of internal medicine, B.P. Koirala Institute of health sciences, Nepal. Results: Both systolic and diastolic blood pressures were significantly higher (≥160 and/or 100 mm Hg) in cases compared to controls (<120/80 mm Hg). Echocardiographic parameters of diastolic dysfunction: E/A ratio, E/E'ratio, deceleration time and isovolumetric relaxation time showed a significant difference between cases and controls. Mean serum NT-proBNP was significantly higher in patients with hypertension (213.19 ±184.3 pg/mL) compared to controls (58.51 ± 11.01 pg/mL) ( P =0.008). There was no significant difference in mean serum NT-pro BNP levels between cases with no LV diastolic dysfunction (n=14) and controls (n=100) but it showed a significant difference between cases with LV diastolic dysfunction of all grades (n=86) and controls (n=100) ( P =0.00). NT-proBNP levels were higher in both group of patients with E/A ratios <0.9 and 0.9-1.5 (245.72 ± 166.73 pg/mL and 210.69 + 143.53 pg/mL respectively) as compared to controls. Mean serum NT-proBNP levels were significantly higher in patients with IVRT >90 ms (270.43 ± 180.81 pg/mL) as compared to controls ( P =0.03) but the difference was not significant between cases with IVRT of 60-90 ms (152.02 ± 100.23 pg/mL) and controls ( P =0.09). NT-proBNP levels were significantly higher in all groups of patients with E/E' ratios <8, 8-12, >12 (197 ± 121.25 pg/mL, 263.12 ± 122.52 pg/mL and 180 ± 106.56 pg/mL respectively) compared to controls. Conclusion: Mean serum NT-proBNP was significantly higher in patients with hypertension as compared to controls. There is some correlation between echocardiographic parameters of diastolic dysfunction and serum NT-proBNP. Hence, NT-proBNP may be useful for early detection of LV diastolic dysfunction in patients with hypertension.