Effects of Exercise Training on Heart Failure Measured Using Seismocardiography

Abstract

Heart failure has become a growing health concern across most of the Western

world and will soon become a global health focus. The nature of the disease presents

with a very high mortality rate. In Canada alone, the average mortality rate is

approximately 50% within the first five years of diagnosis [1]. Exercise has now become

a common treatment modality for many chronic disease conditions including heart

failure. As heart failure advances, the myocardium goes through a remodeling phase that

alters the contractility of the heart and its pumping efficiency. Exercise is known to lead

to a positive remodeling of the myocardium in healthy populations, but the degree to

which exercise reverses pathological remodeling in individuals with heart failure remains

to be determined.

The purpose of this study was to analyze the Systolic Timing Intervals (STI) of

the myocardium, specifically left ventricular ejection time (LVET) and the pre-ejection

period (PEP) using seismocardiography (SCG), as well as to investigate the functional

health changes measured using the six-minute walk test (6MWT). Participants exercised

three times per week for a period of 12 weeks involving a combination of aerobic and

resistance type activities. The SCG screening and 6MWT were performed at the

commencement, and at the 12 week point of their exercise program. Eleven individuals

participated in this study with varying etiologies for heart failure (ischemic n=6 and nonischemic

n=5). Among the individuals with ischemic heart failure, significant

improvement were observed in 6MWT distance, (477.0±127.0m to 539.3±113.9m t(5)=-

3.01, p=0.030), but no significant improvements were noted in indices of myocardial

function. However, in the non-ischemic group, significant changes were noted in indices

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of myocardial function including LVET (449.6±36.0ms to 438.4±30.5ms t(149)=4.28,

p=<0.001), and PEP (128.0±23.5ms to 119.9±18.5ms t(149)=6.87, p=<0.001), but no

statistically significant changes were observed in 6MWT distance (p=0.056). This study

showed that SCG can be used to record the mechanical function of the heart in

individuals with heart failure, that exercise training can produce positive mechanical

changes to the heart for individuals with non-ischemic heart failure, and exercise capacity

can increase in for individuals with ischemic based heart failure.