Serum N-terminal pro-B-type natriuretic peptide levels are associated with left atrial dilation, resting left ventricular outflow tract gradient, and pulmonary hypertension in patients with hypertrophic cardiomyopathy

Introduction
N-terminal pro-B-type natriuretic peptide (NT-proBNP) can be a marker of left ventricle (LV) pressure overload in hypertrophic cardiomyopathy (HCM). The different clinical characteristics of HCM might correspond to the degree of NT-proBNP increase.

Aim
This study aimed to establish whether the left atrium (LA) dimension, left ventricle outflow tract (LVOT) gradient, and pulmonary hypertension influence NT-proBNP serum levels in patients with HCM.

Material and methods
In 62 HCM patients (32 males and 30 females, mean age 31 ±11 years), echocardiography with LV outflow tract gradient provocation was performed using natural stimuli > 30 mm Hg (NOHCM – 36 patients, POHCM – 12 patients, HOCM – 14 patients).

Results
Smaller LAD was associated with a lower NT-proBNP/ULN level (p = 0.001). In contrast, smaller vs. larger LAD subgroups did not differ in NT-proBNP level (p = 0.42). Both NT-proBNP/ULN and NTproBNP were significantly elevated in the subgroup with lager LAA. The absolute value of NT-proBNP was significantly higher in the HOCM subgroup (NOHCM vs. POHCM vs. HOCM (p = 0.02). Similarly, NT-proBNP/ULN was significantly higher in the HOCM subgroup (NOHCM vs. POHCM vs. HOCM, p = 0.00047). This elevated value of biomarker is related to pulmonary hypertension.

Conclusions
Increased NT-proBNP/ULN is positively associated with larger LAD and LAA, while elevated NTproBNP is only associated with larger LAA. The highest levels of both NT-proBNP and NTproBNP/ULN were associated with HOCM and pulmonary hypertension, whereas biomarker levels were comparably lower in both the POHCM and NOHCM.