Therefore,this study will provide critical data on the prevalence of TD in ambulatory patients with HF as well as defining what factors are predictive of TD in this population. Furthermore, this study will determine an effective dose of oral thiamin supplementation that will restore red blood cell thiamin levels. Determining an effective dose will not only justify our choice of thiamin supplementation in future studies but will guide clinicians in recommending thiamin supplementation to their patients with heart failure in the community.