Effect of exercise training on ventricular function, dyssynchrony, resting myocardial perfusion, and clinical outcomes in patients with heart failure: a nuclear ancillary study of Heart Failure and A Controlled Trial Investigating Outcomes of Exercise TraiNing (HF-ACTION); design and rationale.

Background: Technetium Tc 99m gated single photon emission computed tomography (SPECT) has become the cornerstone of noninvasive risk stratification in patients with ischemic heart disease, but its role in patients with heart failure is not as well established.

Study Design: This study is a substudy of the Heart Failure and A Controlled Trial Investigating Outcomes of Exercise TraiNing (HF-ACTION) trial--a National Institutes of Health/National Heart, Lung, and Blood Institute-funded randomized controlled trial--designed to evaluate the role of exercise training in patients with heart failure due to left ventricular dysfunction. For this substudy, a total of 300 patients distributed on an approximately 1:1 basis between the exercise training and usual care arms of HF-ACTION will undergo resting technetium Tc 99m gated SPECT at baseline and 12 months to compare changes in left ventricular function with exercise training. These changes, along with baseline data, will be correlated with changes in exercise parameters, inflammatory markers, and clinical outcomes: death, cardiovascular hospitalization, and quality of life scores. In a subset of patients, first-pass radionuclide ventriculography will be obtained to assess the relationship between ventricular dyssynchrony, ejection fraction, changes in exercise parameters, and outcomes.

Conclusion: The role of nuclear imaging in patients with heart failure remains poorly defined. This substudy aims to harness the power of a large heart failure trial (HF-ACTION) to further delineate the utility of technetium Tc 99m gated SPECT imaging and first-pass radionuclide ventriculography for predicting important clinical outcomes in this population.