Rationale and Design of the CANONICAL Study　- Randomized, Open-Label Study to Evaluate the Efficacy and Safety of Canagliflozin for Heart Failure With Preserved Ejection Fraction With Type 2 Diabetes Mellitus.

Background: Sodium-glucose cotransporter 2 inhibitors (SGLT2-I) have beneficial cardiovascular effects, including reduction in hospitalization for heart failure (HF). The aim of this study is to explore the efficacy and safety of canagliflozin compared with standard diabetes treatment in elderly patients with type 2 diabetes (T2DM) and HF with preserved ejection fraction (HFpEF). Methods and Results: This is a multicenter, randomized, open-label, parallel-group comparison study designed to evaluate the effects of canagliflozin on fluid retention and cardiac function in T2DM patients with HFpEF. Eligible participants are patients aged ≥65 years with insufficient glycemic control. Qualified patients will be randomly assigned to treatment with 100 mg of canagliflozin or standard diabetic treatment other than SGLT2-I; both groups will be treated for 24 weeks. The primary endpoints are changes in body weight as an indicator of fluid retention and plasma brain natriuretic peptide as an indicator of cardiac function. The secondary endpoints include cardiovascular event rates, changes in the dose of loop diuretics, echocardiographic left ventricular function, and nutritional status. Conclusions: This study is expected to provide valuable findings regarding the mechanisms of canagliflozin on cardiac function and a potential new therapeutic approach for HFpEF. (UMIN000028668 and jRCTs051180030).