Association between impaired left ventricular global longitudinal strain and B-type natriuretic peptide in obstructive hypertrophic cardiomyopathy

Abstract Background Left ventricular global longitudinal strain (LV-GLS) is considered valuable in explaining impaired left ventricular contractility in hypertrophic cardiomyopathy (HCM) with preserved ejection fraction and is associated with worse outcome. Elevated B-type natriuretic peptide (BNP) is a biomarker of increased LV wall stretch and a risk factor of heart failure, mortality, and other adverse cardiovascular events. However, relationship between GLS and BNP has not received sufficient attention in the obstructive variant of HCM. Purpose This study aimed to determine the association between echocardiographic LV-GLS and plasma BNP in patients with hypertrophic obstructive cardiomyopathy (HOCM). Methods A total of 145 consecutive patients (32% females) with symptomatic HOCM were enrolled in the retrospective study. HOCM was defined with a maximum end-diastolic wall thickness ≥15mm without other etiologies for LV hypertrophy, and peak LV outflow tract (LVOT) gradient ≥30mmHg. The echocardiographic parameters regarding LV geometry, loading conditions, and GLS were evaluated according to guidelines. Patients were divided into two groups according to absolute GLS values (greater or lower than median LV-GLS). Patient baseline clinical data, echocardiographic parameters, and BNP were compared. Univariate and multivariable regression analysis were applied to identify the independent determinator of LV-GLS. Results The median value of LV-GLS of this study cohort was -13.4%. Eighty-one patients (47.6±13.4 years-old) had a |GLS|≥13.4% and 64 individuals (48.7±12.6 years-old) had a |GLS|<13.4%. No differences were found in age, gender, physical examinations, LVEF, cardiovascular comorbidities, or active medications between the two groups, except for body mass index (BMI). Patients with |GLS|≥13.4% had statistically lower BMI (24.58±2.42 vs. 26.00±3.12kg/m², p=0.030). BNP was found significantly elevated in patients with |GLS|<13.4% when compared with individuals with |GLS|≥13.4% {median (IQR); 550.05 (214.50, 899.35) vs. 182.40 (78.90, 479.90)pg/mL, p=0.004}. In univariate regression analysis, decreased |GLS| was associated with male gender, maximum and mean LV wall thickness, peak LVOT gradient, reduced mitral annular e’ velocity, elevated BNP and cardiac troponin I. In multivariable regression analysis, GLS was found independently associated with mean LV wall thickness and BNP. Conclusions In patients with symptomatic HOCM with preserved ejection fraction, impaired LV-GLS was found to be associated with plasma BNP and mean LV wall thickness, independent of gender, age, loading conditions, LVEF, or LVOT gradient. Reduced GLS may be a more sensitive surrogate in assessing increased myocardial wall tension or stretch, rather than LV contractility in these patients. Therefore, the interpretation of GLS in HOCM should shift away from systolic interest toward emphasizing its potential value in risk stratification of diastolic heart failure with preserved LVEF.Figure 1