Silent myocardial infarction during hypoglycaemic coma

A case of silent myocardial infarction associated with hypoglycaemic coma is described. A hypoglycaemic episode represents a risk factor for a patient with underlying ischaemic heart disease. A routine ECG may be indicated in such circumstances. (7Accid Emerg Med 1996;13:357-358) Key terms: hypoglycaemia; diabetes mellitus; myocardial infarction Case report A 75 year old woman with ischaemic heart disease and non-insulin-dependent diabetes mellitus controlled by metformin presented to the emergency department following a period of unconsciousness at home. The patient had been found by her daughter and was described Emergency as being cold, clammy, and unrousable. An Department, North ambulance was called, and on arrival at the Staffordshire Hospit scene the crew made a provisional diagnosis of Road, Hartshill, hypoglycaemia and put jam and sugar into the Stoke-on-Trent, unconscious patient' s mouth. Within minutes Staffordshire, United she had regained consciousness and was Kingdom talking to her rescuers. F M Saunders On arrival at the emergency department the T Liewellyn patient was fully conscious and alert, with no Correspondence to: history of chest pain either before or after her Dr F M Saunders, Registrar period of unconsciousness. Clinical observain Accident and Emergency tions were normal and a Glucostix test gave a Medicine, Accident and Emergency Department, reading of 16.4 mmol/litre. A routine ECG was Royal Preston Hospital, requested by the nursing staff and this revealed Sharoe Green Lane North, evidence of an acute inferior myocardial Fulwood, Preston PR2 9HT. infarction, with 5 mm of ST elevation in leads Accepted for publication II, III, and aVF and T wave inversion in III and 13 March 1996. aVF. The patient was immediately transferred to the resuscitation area and the medical staff informed. Clinical examination revealed a raised jugular venous pressure, mild ankle oedema, and severe diabetic retinopathy, but was otherwise unremarkable. Formal laboratory blood glucose estimation confirmed the reading of 16.4 mmol/litre. A diagnosis of silent myocardial infarction was made and the patient was admitted to an acute medical ward. Serial ECGs and serum aspartate transaminase and creatine kinase estimations over the next 72 hours confirmed the diagnosis. She had an uneventful hospital stay and was discharged home seven days later. Discussion It is recognised that hypoglycaemia increases damage to the ischaemic myocardium.' However, few cases of myocardial infarction associated with hypoglycaemia have previously been reported.2' Others have described ischaemic ECG changes during severe hypoglycaemia which resolved completely after treatment with intravenous glucose.4 The development of hypoglycaemia was not preceded by chest pain in any of these cases. It has been shown that autonomic neuropathy in diabetes mellitus leads to disturbed cardiac perception and thus may play a role in silent myocardial infarction.5 Myocardial infarction normally tends to increase the blood sugar because of a decrease in insulin sensitivity6; therefore, had it been the primary event in our patient, symptomatic hypoglycaemia would have been less likely. Although we have no biochemical proof that group.bmj.com on June 19, 2017 Published by http://emj.bmj.com/ Downloaded from