Impaired longitudinal systolic-diastolic coupling and cardiac response to exercise in patients with hypertrophic cardiomyopathy.

MacNamara JP; Division of Cardiovascular Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Turlington WM;Dias KA; Hearon CM Jr; Ivey E; Delgado VA; Brazile TL; Wakeham DJ;Turer AT;Link MS;Levine BD; Sarma ;

Echocardiography (Mount Kisco, N.Y.) [Echocardiography] 2024 Jun; Vol. 41 (6), pp. e15857.

Background: In patients with hypertrophic cardiomyopathy (HCM), impaired augmentation of stroke volume and diastolic dysfunction contribute to exercise intolerance. Systolic-diastolic (S-D) coupling characterizes how systolic contraction of the left ventricle (LV) primes efficient elastic recoil during early diastole. Impaired S-D coupling may contribute to the impaired cardiac response to exercise in patients with HCM.
Methods: Patients with HCM (n = 25, age = 47 ± 9 years) and healthy adults (n = 115, age = 49 ± 10 years) underwent a cardiopulmonary exercise testing (CPET) and echocardiogram. S-D coupling was defined as the ratio of LV longitudinal excursion of the mitral annulus during early diastole (ED exc ) and systole (S exc ) and compared between groups. Peak oxygen uptake (peak V̇O 2 ) (Douglas bags), cardiac index (C 2 H 2 rebreathe), and stroke volume index (SVi) were assessed during CPET. Linear regression was performed between S-D coupling and peak V̇O 2 , peak cardiac index, and peak SVi.
Results: S-D coupling was lower in HCM (Controls: 0.63 ± 0.08, HCM: 0.56 ± 0.10, p < 0.001). Peak V̇O 2 and stroke volume reserve were lower in patients with HCM (Peak VO 2 Controls: 28.5 ± 5.5, HCM: 23.7 ± 7.2 mL/kg/min, p < 0.001, SV reserve: Controls 39 ± 16, HCM 30 ± 18 mL, p = 0.008). In patients with HCM, S-D coupling was associated with peak V̇O 2 (r = 0.47, p = 0.018), peak cardiac index (r = 0.60, p = 0.002), and peak SVi (r = 0.63, p < 0.001).
Conclusion: Systolic-diastolic coupling was impaired in patients with HCM and was associated with fitness and the cardiac response to exercise. Inefficient S-D coupling may link insufficient stroke volume generation, diastolic dysfunction, and exercise intolerance in HCM.