Associations of Cardiac Mechanics With Exercise Capacity: The Multi-Ethnic Study of Atherosclerosis.

Background: Lower exercise capacity, as measured by 6-minute walk distance (6MWD), is associated with incident heart failure (HF). Among those without HF, the associations of measures of cardiac function with 6MWD are unclear, and may provide insight regarding the risk of incident HF.
Objectives: The purpose of this study was to understand the relationships between cardiac function and exercise capacity.
Methods: This study evaluated the associations of cardiac mechanics with 6MWD in the sixth examination of the Multi-Ethnic Study of Atherosclerosis. Echocardiography (2-dimensional, Doppler, and speckle-tracking) was performed at rest and after passive leg raise to evaluate functional reserve after intravascular volume challenge.
Results: Of 2,096 participants without HF (mean age 73 years, 48% men, 58% non-White), individuals with lower (worse) left atrial (LA) reservoir strain were older and had higher blood pressure. Lower resting LA reservoir strain (β coefficient per SD decrease: -5.0; 95% confidence interval [CI]: -8.8 to -1.3 m; p = 0.009), inability to augment LA reservoir strain after passive leg raise (β coefficient per SD decrease: -5.8; 95% CI: -9.1 to -2.5 m; p < 0.001), and lower right atrial reservoir strain (β coefficient per SD decrease: -4.4; 95% CI: -7.8 to -1.1 m; p = 0.01) were associated with shorter 6MWD. Worse left ventricular (LV) diastolic function was also associated with lower 6MWD. There were no independent associations of measures of LV systolic function (global longitudinal strain, circumferential strain, ejection fraction) with 6MWD.
Conclusions: Among individuals without HF, worse biatrial function, lack of LA functional reserve, and worse LV diastolic function were associated with reduced submaximal exercise capacity. Therapies aimed to improve these functional domains may increase exercise capacity and prevent HF.
Competing Interests: Funding Support and Author Disclosures This research was supported by contracts 75N92020D00001, HHSN268201500003I, N01-HC-95159, 75N92020D00005, N01-HC-95160, 75N92020D00002, N01-HC-95161, 75N92020D00003, N01-HC-95162, 75N92020D00006, N01-HC-95163, 75N92020D00004, N01-HC-95164, 75N92020D00007, N01-HC-95165, N01-HC-95166, N01-HC-95167, N01-HC-95168, and N01-HC-95169 from the National Heart, Lung, and Blood Institute; by grants KL2TR001424, UL1-TR-000040, UL1-TR-001079, and UL1-TR-001420 from the National Center for Advancing Translational Sciences; and by grants R01 HL127028, R01 HL127659, and R01 AG18915 from the National Institutes of Health. Dr. Shah has received research grants from Actelion, AstraZeneca, Corvia, Novartis, and Pfizer; and has received consulting fees from Abbott, Actelion, AstraZeneca, Amgen, Axon Therapies, Bayer, Boehringer Ingelheim, Bristol Myers Squibb, Cardiora, CVRx, Cytokinetics, Eisai, GlaxoSmithKline, Ionis, Ironwood, Lilly, Merck, MyoKardia, Novartis, Novo Nordisk, Pfizer, Sanofi, Shifamed, Tenax, and United Therapeutics. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
(Copyright © 2021 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)