A Trial of Thiamin Supplementation in Patients With Heart Failure

Background: There is now accumulating evidence that patients with heart failure (HF) have a high prevalence of thiamin deficiency (TD). Since thiamin is a key cofactor in the enzyme systems that produce energy from both carbohydrates and fats, TD may contribute to the energy depletion frequently observed in the failing heart. Altered energy reserves with a reduction in myocardial ATP have now been recognized to play a critical role in the development and progression of HF. Therefore, correction of TD may enhance cardiac energy substrate availability and utilization, leading to improvement of ventricular function and symptoms. Primary Hypothesis: The left ventricular ejection fraction in stable, ambulatory patients with systolic heart failure receiving 6 months of oral thiamin supplementation will be significantly higher in comparison with those receiving a placebo. Secondary Hypothesis: In heart failure patients oral thiamin supplementation will 1)have favourable effects on ventricular remodelling (reduction in diastolic and systolic volumes) and regional function; 2)reduce neurohormonal stimulation (BNP and norepinephrine) as well as oxidative stress; 3)improve exercise capacity and 4)improve symptoms and quality of life. Ambulatory patients attending heart failure clinics at Mount Sinai, University Health Network, Trillium Health Centre and St. Michael's Hospital with systolic heart failure (NYHA class II-IV, left ventricular ejection fraction \<45%) will be screened for eligibility to participate in our randomized trial. We will randomize seventy eligible patients using a stratified, permuted block randomization scheme, to be given either 100mg BID of thiamin HCl or a matching placebo BID in a 1:1 ratio to be taken for six months. All study personnel will be blinded to treatment assignment. Participants will have baseline and follow-up visits which include collecting demographic data, history of medication use, symptoms, anthropometrics as well as a physical exam. Left ventricular ejection fraction, volumes, and regional function will be measured using a standardized echocardiogram and cardiac MRI at baseline and after six months of supplementation. At this time, blood markers of thiamin status, oxidative stress (F2 isoprostanes) and neurohormonal activation (norepinephrine and BNP) will also be measured. Participants will also complete a six-minute walk test, a 3-day dietary record, the Living with Heart Failure quality of life instrument and a 24-hour urine collection (to measure urinary thiamin excretion) at both baseline and follow-up visits. Compliance will be measured using returned pill counts and verified by measuring plasma thiamin levels which respond rapidly to thiamin supplementation.