Rationale:Altered cardiac energetics is known to play an important role in the progression toward heart failure. A noninvasive method for imaging metabolic markers that could be used in longitudinal studies would be useful for understanding therapeutic approaches that target metabolism.Objective:To demonstrate the first hyperpolarized 13C metabolic magnetic resonance imaging of the human heart.Methods and Results:Four healthy subjects underwent conventional proton cardiac magnetic resonance imaging followed by 13C imaging and spectroscopic acquisition immediately after intravenous administration of a 0.1 mmol/kg dose of hyperpolarized [1-13C]pyruvate. All subjects tolerated the procedure well with no adverse effects reported ≤1 month post procedure. The [1-13C]pyruvate signal appeared within the chambers but not within the muscle. Imaging of the downstream metabolites showed 13C-bicarbonate signal mainly confined to the left ventricular myocardium, whereas the [1-13C]lactate signal appeared both within the chambers and in the myocardium. The mean 13C image signal:noise ratio was 115 for [1-13C]pyruvate, 56 for 13C-bicarbonate, and 53 for [1-13C]lactate.Conclusions:These results represent the first 13C images of the human heart. The appearance of 13C-bicarbonate signal after administration of hyperpolarized [1-13C]pyruvate was readily detected in this healthy cohort (n=4). This shows that assessment of pyruvate metabolism in vivo in humans is feasible using current technology.Clinical Trial Registration:URL: https://www.clinicaltrials.gov. Unique identifier: NCT02648009.

Background: SGLT2 (sodium-glucose cotransporter 2) inhibitors lower cardiovascular events in type 2 diabetes mellitus but whether they promote direct cardiac effects remains unknown. We sought to determine if empagliflozin causes a decrease in left ventricular (LV) mass in people with type 2 diabetes mellitus and coronary artery disease. Methods: Between November 2016 and April 2018, we recruited 97 individuals ≥40 and ≤80 years old with glycated hemoglobin 6.5% to 10.0%, known coronary artery disease, and estimated glomerular filtration rate ≥60mL/min/1.73m 2 . The participants were randomized to empagliflozin (10 mg/day, n=49) or placebo (n=48) for 6 months, in addition to standard of care. The primary outcome was the 6-month change in LV mass indexed to body surface area from baseline as measured by cardiac magnetic resonance imaging. Other measures included 6-month changes in LV end-diastolic and -systolic volumes indexed to body surface area, ejection fraction, 24-hour ambulatory blood pressure, hematocrit, and NT-proBNP (N-terminal pro b-type natriuretic peptide). Results: Among the 97 participants (90 men [93%], mean [standard deviation] age 62.8 [9.0] years, type 2 diabetes mellitus duration 11.0 [8.2] years, estimated glomerular filtration rate 88.4 [16.9] mL/min/1.73m 2 , LV mass indexed to body surface area 60.7 [11.9] g/m 2 ), 90 had evaluable imaging at follow-up. Mean LV mass indexed to body surface area regression over 6 months was 2.6 g/m 2 and 0.01 g/m 2 for those assigned empagliflozin and placebo, respectively (adjusted difference −3.35 g/m 2 ; 95% CI, −5.9 to −0.81g/m 2 , P =0.01). In the empagliflozin-allocated group, there was significant lowering of overall ambulatory systolic blood pressure (adjusted difference −6.8mmHg, 95% CI −11.2 to −2.3mmHg, P =0.003), diastolic blood pressure (adjusted difference −3.2mmHg; 95% CI, −5.8 to −0.6mmHg, P =0.02) and elevation of hematocrit ( P =0.0003). Conclusions: Among people with type 2 diabetes mellitus and coronary artery disease, SGLT2 inhibition with empagliflozin was associated with significant reduction in LV mass indexed to body surface area after 6 months, which may account in part for the beneficial cardiovascular outcomes observed in the EMPA-REG OUTCOME (BI 10773 [Empagliflozin] Cardiovascular Outcome Event Trial in Type 2 Diabetes Mellitus Patients) trial. Clinical Trial Registration: URL: https://www.clinicaltrials.gov . Unique identifier: NCT02998970.

Hyperpolarization of spins via dynamic nuclear polarization (DNP) has been explored as a method to non-invasively study real-time metabolic rocesses occurring in vivo using 13 C-labeled substrates. Recently, hyperpolarized 13 C pyruvate has been used to characterize in vivo cardiac metabolism in the rat and pig. Conventional 3D spectroscopic imaging methods require in excess of 100 excitations, making it challenging to acquire a full cardiac-gated, breath-held, whole-heart volume. In this article, the development of a rapid multislice cardiac-gated spiral 13 C imaging pulse sequence consisting of a large flip-angle spectral-spatial excitation RF pulse combined with a singleshot spiral k-space trajectory for rapid imaging of cardiac metabolism is described. This sequence permits whole-heart coverage (6 slices, 8.

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