Why the study?
The associations of measures of cardiac structure and function with exercise capacity in individuals without heart failure are unclear and may provide insight into incident heart failure risk.
Are worse resting biatrial and left ventricular mechanical function indices, and lack of left atrial functional reserve, associated with reduced 6-minute walk distance in older adults without heart failure?
Cohort (n=2,096)
Yes
Are worse resting biatrial and left ventricular mechanical function indices, and lack of left atrial functional reserve, associated with reduced 6-minute walk distance in older adults without heart failure?
Effect estimate: β coefficient per SD decrease: -5.0 meters (95% CI -8.8, -1.3)
p-value: p=0.009
Captured external expert commentary on this paper, strongest first. Original sources are linked where available.
“To put the results into perspective, we need to discuss what LA reservoir strain actually measures. Is LV systolic function not that important? First, from a mechanical point of view, it is difficult to accept that LV longitudinal systolic function is not an important component or determinant of LA reservoir strain. If we accept the concept of a stationary LV apex and LA base, LA reservoir strain would equal mitral annular displacement indexed to LA size, whereas LV GLS would equal mitral annular displacement indexed to LV size. The results presented in the paper suggest that there was less pathological LV dilatation than LA dilatation in the population. Thus, LA volume, and consequently LA reservoir strain, would be the better variable for differentiating different degrees of pathology in this population.”
Among adults without heart failure, worse biatrial reservoir function, inability to augment left atrial strain during volume challenge, and left ventricular diastolic dysfunction are independently associated with reduced submaximal exercise capacity.
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 structure and function with 6MWD are unclear, and may provide insight regarding the risk of incident HF. Objectives: To understand the relationships between cardiac function and exercise capacity. Methods: We evaluated the associations of cardiac mechanics with 6MWD in the 6th exam of the Multi-Ethnic Study of Atherosclerosis. Two-dimensional, Doppler and speckle-tracking echocardiography 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, 48% male, 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% CI: −8.8, −1.3 meters; P=0.009), inability to augment LA reservoir strain after passive leg raise (β coefficient per SD decrease: −5.8, 95% CI: −9.1, −2.5 meters; P<0.001), and lower right atrial reservoir strain (β coefficient per SD decrease: −4.4, 95% CI: −7.8, −1.1 meters; 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 indices of LV systolic function (global longitudinal strain, circumferential strain, ejection fraction) with 6MWD. Conclusion: 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.
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Patel et al. (2021) conducted a cohort in Free of heart failure (n=2,096). Lower resting left atrial (LA) reservoir strain vs. Higher resting left atrial (LA) reservoir strain was evaluated on 6-minute walk distance (6MWD) (β coefficient per SD decrease: -5.0 meters, 95% CI -8.8, -1.3, p=0.009).
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