The Relationship between Hypoglycaemic Episodes and Arrhythmias in Type 2 Diabetes Subjects after Acute Myocardial Infarction with ST-Segment Elevation—A Case Series

Background and Aims: Several studies have shown that hypoglycaemia, especially a severe episode is associated with an increased mortality rate in diabetes mellitus subjects with previous cardiovascular disease or acute coronary syndrome. One of the presumed mechanisms is the proarrhythmic effect of hypoglycaemia related to the prolongation of the action potential, or the catecholamine surge that follows an episode. The aim of this case series analysis was to investigate the relationship between hypoglycaemia and glucose variability with arrhythmic events in type 2 diabetes patients who suffered an acute myocardial infarction. Materials and Methods: We selected patients admitted consecutively to the cardiology department of Clinical Emergency Hospital in Bucharest for a period of three months with acute myocardial infarction and previously diagnosed type 2 diabetes. For each patient, a retrospective continuous glucose monitoring system (CGMS) or glucose sensor (Medtronic® Enlite, USA) and a dual electrocardiograph and blood pressure monitor for 24 hours were available. Also, patients had an oscillometric device (Arteriograph® TensioMed Ltd) for 24 hours or non-invasive monitoring of central blood pressure, pulse wave velocity and augmentation index. The data were analysed using Medtech®, TensioWin® and Carelink iPro® softwares. We used SPSS® version 20.0 (IBM) for the statistical analysis. The results are presented as median and interquartile range (IQR). Results and Discussion: Ten type 2 diabetes patients (4 males, 6 females) with anterior (4/10) and inferior acute myocardial infarction (6/10) were included. They were treated with insulin (3/10), sulphonylurea (Gliclazide) plus Metformin (4/10), Metformin monotherapy (2/10), or all three (1/10). The patients had a median age of 67.5 (3.25) years with a median disease duration of 8 (7.75) years. The median body mass index was 29.54 (5.65) kg/m2. The median HbA1c was 7.9% (3.15) % and C-peptide 3.3 (2.66) ng/ml. There were no significant differences regarding the number of atrial or ventricular premature beats, ventricular or atrial tachycardia or fibrillation, the duration of QT interval, systolic and diastolic blood pressure, aortic pressure, augmentation index, pulse wave velocity between subjects with hypoglycaemia and those without. There was a negative correlation between QTc and glucose values in patients with hypoglycaemia (Spearman coefficient correlation r = -0.232; p < 0.01). Conclusion: Mild hypoglycaemia in type 2 diabetes patients with systolic dysfunction after ST-elevated myocardial infarction did not increase the number of supraventricular premature beats and QTc duration. We suggest that non-severe hypoglycaemia does not increase the risk of arrhythmias in patients with type 2 diabetes.