Regional differences in myocardial performance in patients with obstructive hypertrophic cardiomyopathy
A Moya, W Heggermont, J Dauw, R Dierckx, E Bogaerts, L Roseel, E De Vuyst, M VanderheydenAbstract
Introduction
Hypertrophic cardiomyopathy (HCM) is characterized by an abnormal myocardial wall thickening with subsequent impact on cardiac performance, particularly in the presence of left ventricular outflow track (LVOT) obstruction. The development of a dynamic pressure gradient in the outflow tract might lead to regional remodeling and dysfunction which in turn may compromise the global myocardial performance.
Aim
This study investigates regional differences in myocardial function in patients with obstructive HCM by assessing regional myocardial work (MW).
Methods
Eleven patients with obstructive HCM referred for mavacantem therapy were included along with 10 patients with severe aortic valve stenosis (AS) as a control. Prior to initiating therapy, all participants underwent transthoracic echocardiography with strain analysis. In HCM patients, the LV pressure was estimated by adding the average of LVOT peak and mean gradient to the peripheral systolic pressure enabling non-invasive global and regional MW assessment (Batzner et al. 2024). Similarly, for AS patients the mean gradient over the aortic valve was added to the systolic blood pressure for MW calculation (Fortuni et al. 2021).
Results
Patient characteristics are detailed in Table 1. HCM patients showed a significant difference in wall thickness between the anteroseptal and posterior segments, indicative of regional remodeling. While longitudinal strain showed no regional variation, a significant difference in MW was observed between the anteroseptal and posterior segments with lower constructive work at the septum (CW: 1606±637 vs 2598±1032mmHg%) and elevated wasted work in the posterior wall (WW: 97±87 vs 194±106mmHg%). Conversely, AS patients showed no regional differences in either wall thickness or MW (Figure 1). The loss of contractile capacity at the septum may be linked to increased LV mass and fibrosis (Xiao et al. 2023). Septal fibrosis could disrupt myocardial conduction leading to a delayed contraction of the posterior wall with an increase in constructive and wasted work, potentially as the posterior wall attempts to compensate for higher intraventricular pressure (at late systole) or even contract after valve closure (post-systolic contraction).
Conclusion
Regional remodeling in obstructive HCM is linked to regional variations in myocardial performance. The thickening of the septum is associated with a loss of contractile capacity compared to the posterior wall which, although it performs more work, does not contract necessarily more efficiently. These findings enhance our understanding of the hemodynamics in hypertrophic hearts. Nevertheless, larger studies are warranted to confirm these findings.For image description, please refer to the figure legend and surrounding text.For image description, please refer to the figure legend and surrounding text.