A Contemporary Review of the Effects of Exercise Training on Cardiac Structure and Function and Cardiovascular Risk Profile: Insights From Imaging

Abstract

Exercise is a commonly prescribed therapy for patients with established cardiovascular disease or those at high risk for de novo disease. Exercise-based, multidisciplinary programs have been associated with improved clinical outcomes post myocardial infarction and is now recommended for patients with cancer at elevated risk for cardiovascular complications. Imaging studies have documented numerous beneficial effects of exercise on cardiac structure and function, vascular function and more recently on the cardiovascular risk profile. In this contemporary review, we will discuss the effects of exercise training on imaging-derived cardiovascular outcomes. For cardiac imaging via echocardiography or magnetic resonance, we will review the effects of exercise on left ventricular function and remodeling in patients with established or at risk for cardiac disease (myocardial infarction, heart failure, cancer survivors), and the potential utility of exercise stress to assess cardiac reserve. Exercise training also has salient effects on vascular function and health including the attenuation of age-associated arterial stiffness and thickening as assessed by Doppler ultrasound. Finally, we will review recent data on the relationship between exercise training and regional adipose tissue deposition, an emerging marker of cardiovascular risk. Imaging provides comprehensive and accurate quantification of cardiac, vascular and cardiometabolic health, and may allow refinement of risk stratification in select patient populations. Future studies are needed to evaluate the clinical utility of novel imaging metrics following exercise training.

Keywords: body composition; cardiovascular disease; exercise training; imaging; left ventricular function; vascular function.

Figure 1

Examples of cardiac imaging metrics to assess the effects of exercise training in patients with or at risk for cardiovascular disease. (A) Left ventricular volumetric analysis of short-axis steady state free precession (SSFP) images acquired from cardiac MRI. (B) Global longitudinal strain acquired transthoracic echocardiogram. (C) Myocardial perfusion acquired from first-pass gadolinium enhanced imaging on vasodilator stress cardiac MRI. Note anterolateral perfusion defect (white arrows). (D) Myocardial tissue characterization on cardiac MRI with native T1 mapping (left) and extracellular volume fraction (ECV) (right). Note the elevated myocardial T1 (1,158 ms) and ECV (57%) consistent with cardiac amyloidosis.

Figure 2

Real-time imaging of cardiac function during exercise using cardiac MRI. (A) Healthy volunteer in supine position outside of magnet bore using MRI conditional stepper device to achieve maximal aerobic activity. (B) All short-axis and long-axis slices are viewed simultaneously to select those for volumetric analysis. Short-axis slices with myocardium and a single 2- and 4-chamber view are chosen. (C) A full cardiac cycle for each selected slice is extracted from which end-diastolic and end-systolic images are identified and endocardial (red) and epicardial (green) borders are traced. Modified from Kirkham et al. (97).

Figure 3

Imaging techniques used to assess the effects of exercise training in patients with or at risk for cardiovascular disease. (A) MRI derived arterial stiffness. Pulse wave velocity (PWV) estimated from MRI derived phase velocity imaging of the thoracic aorta in an older patient with heart failure. Adapted from Thompson et al. (101). (B) Thoracic aorta distensibility (AoD) on SSFP cines. Comparison of aortic distensibility between a young healthy individual, an older healthy individual and an older patient with heart failure.

Figure 4

Examples of MRI T1 mapping sequences to assess the extra-cardiac effects of exercise training in patients with or at risk for cardiovascular disease. (A) Abdominal fat density (B) Skeletal muscle fat compartments. Dark signal = fat.