Fursultiamine is a synthetic derivative of thiamine (vitamin B1) designed to have higher bioavailability and better tissue penetration. Thiamine is well established as an essential nutrient for carbohydrate metabolism, and its deficiency can lead to cardiovascular complications, most notably "wet beriberi," which is characterized by heart failure and edema. The use of thiamine supplementation—including fursultiamine—is scientifically validated for the treatment and prevention of heart dysfunction specifically in the context of thiamine deficiency. Several clinical studies and case reports document improvements in cardiac function, reversal of heart failure symptoms, and overall cardiovascular health upon thiamine repletion in deficient states.

However, beyond deficiency states, the evidence supporting the use of fursultiamine or thiamine for treating or supporting general "heart weakness" (in the absence of proven deficiency) is limited and not robust. Some small studies and preliminary investigations have suggested possible benefits for patients with heart failure, but large-scale, high-quality randomized controlled trials are lacking. Therefore, while there is a solid scientific rationale for using fursultiamine in cases of thiamine deficiency–induced heart dysfunction, its use for general cardiac support in non-deficient individuals is not well established. The strength of evidence is rated as 2/5 due to the clear benefit in deficiency but insufficient data for broader applications.