Relation of biological and functional left ventricular remodeling to obstruction in hypertrophic cardiomyopathy: A rest and exercise echocardiographic study with longitudinal strain measurement

Abstract

Outflow tract obstruction is thought to be involved in left ventricular (LV) remodeling in sarcomeric hypertrophic cardiomyopathy (HCM). To determine the influence of obstruction to biological parameters of remodeling and global longitudinal strain (GLS) in HCM. Patients with HCM who accepted to participate to this study were included. Transthoracic echocardiography at rest and exercise with GLS measurement was carried out. Blood was sampled before and early after exercise. Patients were divided into 3 groups according to the presence of an obstruction at rest (OHCM), effort (Latent obstruction: LOHCM) or none (HCM). We included 40 HCM patients, 7 OHCM, 19 LOHCM and 14 NOHCM. Troponin-T and NTproBNP levels at rest were significantly higher in OHCM compared to NOHCM (19.5 ± 10 vs 10 ± 5.8 ng/L, P = 0.017 and 1184 ± 389 vs 520 ± 388 ng/L, P = 0.005). Troponin-T and NTproBNP levels at rest were correlated with the outflow tract peak gradient ( r = 0.49, P = 0.001 and r = 0.41, P = 0.005, respectively) and with the alteration of GLS ( r = 0.51, P = 0.001 and r = 0.46, P = 0.003, respectively). GLS at rest was significantly more altered in OHCM. After exercise ST2, IL6, GDF15, Troponin-T and NTproBNP increased significantly in OHCM + LOHCM while only NTproBNP increased in NOHCM. In multivariate analysis, postexercise Troponin-T ( β = 0.57, P < 0.0001) was a determinant of GLS at rest ( Fig. 1 ). In HCM, biological parameters of remodeling are correlated to obstruction and GLS. GLS is itself correlated with the outflow peak gradient. Exercise in obstructive forms of HCM induces a significant increase in multiple biological parameters of remodeling. Troponin-T level is a strong predictor of GLS alteration both at rest and exercise.