Novel Imaging of Hypoglycemia-induced Myocardial Abnormality by Cardiac Magnetic Resonance T1-mapping.

A 66-year-old man was admitted to our department because of chest discomfort. He had a history of anti-insulin-antibody-positive type 2 diabetes and had required insulin for 20 years. Electrocardiography showed new ST-wave depression and T-wave inversion in the left precordial leads (Picture 1). Echocardiography showed normal left ventricular wall motion with no valvular abnormalities. His plasma glucose level was 59 mg/dL, and cardiac-troponin-I was 0.21 ng/mL. Multi-detector row computed tomography coronary angiography revealed non-obstructive coronary artery disease (Picture 2). One month later, to determine the effect of hypoglycemia on myocardium, we performed cardiac magnetic resonance including T1-mapping, which provides superior detection of diffuse myocardial changes (1). Using the glucose clamp technique, his glucose was controlled to 70 mg/dL for 3 h. Based on modified Look-Locker sequences, the native T1-mapping was diffusely prolonged during hypoglycemia (1,121±51 ms) and normalized (983±47 ms; p<0.01) after recovery to normoglycemia (124 mg/dL glucose) (Picture 3). Treatment-related hypoglycemia increases the risk of adverse cardiovascular events. Multiple mechanisms, such as sympathoadrenal system activation, endothelial dysfunction, inflammation, and blood coagulation abnormalities in hypoglycemia, may affect cardiovascular events (2). In the diabetic heart, energy substrate selection is complex. Insulin stimulates a metabolic switch from the predominant use of fatty acid to glucose (3), and a deficient source of fuel might transiently induce myocardial pathological changes by hypoglycemia-triggered mechanisms (4), but conventional imaging and biochemical examinations cannot detect these hypoglycemia-derived myocardial changes. We quantitatively identified for the first time a hypoglycemia-induced abnormal condition in the left ventricular myocardium using T1-mapping imaging.

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The authors state that they have no Conflict of Interest (COI).