Asymptomatic coronary artery disease among diabetes mellitus patients at Mulago Hospital

Abstract

Cardiovascular disease is the major cause of morbidity and mortality for patients with diabetes. Compared with the general population, patients with diabetes have a 4 times greater incidence of Coronary heart disease and a 2 to 4 fold higher risk of a cardiovascular event. In most diabetic patients, the occurrence of acute myocardial infarction is often asymptomatic, usually because of autonomic neuropathy. Aims: To determine the proportion of diabetic and non-diabetic study participants with asymptomatic CAD using the exercise stress ECG and to establish the risk factors for CAD in these patients Materials and methods This was a cross sectional study involving 122 asymptomatic coronary disease diabetic and non-diabetic participants with no prior history of a cardiac event. Participants had a physical exam done after which blood samples were collected for analysis of lipid profiles, random blood glucose, and HbA1c levels. Participants then undertook a maximal ECG stress test for detection of exercise limited ischemia. Approval to carry out the study was sought from the School of Biomedical Sciences, research IRB and informed consent was given by the study participants.

Results The ECG stress test was positive for CAD in eight (8) out of 61 participants. Among them, 7 (88%) were diabetic and 1 (12%) was non-diabetic. More females (88%) tested positive for CAD than males (12%). CAD patients had a higher mean plasma random blood glucose (269 ± 168 mg/dl) than CAD negative subjects (155 ± 80 mg/dl), and the difference observed was statistically significant (p=0.003). Additionally, slightly more participants (63%) with a CAD diagnosis had a hemoglobin A1c greater 6.5%. Although Dyslipidemia was not independently associated with CAD (p=0.83) in this study, the mean total cholesterol (5.4 ± 1.4 mmol/l) and triglyceride (1.8 ± 1.2 mmol/l) levels were higher than normal in participants with positive ECG ischemic findings compared to those with negative results. CAD positive patients had a poor exercise tolerance during the exercise stress test (6.9 ± 2.8 minutes and 8.5 ± 3 METs Vs 7.3 ± 1.0 minutes and 8.7 ± 2.0 METs) Conclusion Exercise induced ischemia was present in 19% of diabetic patients compared to 4% of non-diabetic participants. More females than males tested positive for Coronary artery disease. In contrast to previous studies, although Coronary artery disease risk factors were highly prevalent in subjects with CAD, they were not significantly associated with inducible ischemia.