Cardiac mechanics predicts exercise capacity in individuals without heart failure

Worse left ventricular (LV) diastolic function, worse biatrial function, and lack of left atrial (LA) functional reserve appear to reduce submaximal exercise capacity among individuals without heart failure (HF), according to a study. Therapies targeted at improving these functional domains may improve exercise capacity and prevent HF.

The authors evaluated the relationships of cardiac mechanics with 6-minute walking distance (6MWD) in the sixth examination of the Multi-Ethnic Study of Atherosclerosis. They performed echocardiography (2-dimensional, Doppler, and speckle-training) at rest and after passive leg raise to assess functional reserve after intravascular volume challenge.

A total of 2,096 participants without HF (mean age 73 years, 48 percent men, 58 percent non-White) were included; those with lower (worse) LA reservoir were older and had higher blood pressure.

Lower resting LA reservoir strain (β coefficient per standard deviation [SD] decrease, –5.0 m, 95 percent confidence interval [CI], –8.8 to –1.3; p=0.009), inability to augment LA reservoir strain after passive leg raise (β coefficient per SD decrease, –5.8 m, 95 percent CI, –9.1 to –2.5 m; p<0.001), and lower right atrial reservoir strain (β coefficient per SD decrease, –4.4 m, 95 percent CI, –7.8 to –1.1; p=0.01) correlated with shorter 6MWD. In addition, worse LV diastolic function correlated with lower 6MWD.

No independent associations were observed between measures of LV systolic function (global longitudinal strain, circumferential strain, ejection fraction) and 6MWD.

“Lower exercise capacity, as measured by 6MWD, is associated with incident HF,” the authors noted. “Among those without HF, the associations of measures of cardiac function with 6MWD … may provide insight regarding the risk of incident HF.”