MYOCARDIAL INFARCTION IN DIABETICS

CIRCADIAN PERIODICITY IN THE ONSET OF ACUTE ST SEGMENT ELEVATION

Abstract

Objective: To analyze the influence of diabetes mellitus on circadian rhythm affecting the onset of acute ST elevation myocardial infarction. Design: Observational study. Period: February to August 2010. Setting: Faisalabad Institute of Cardiology, Faisalabad. Materials and methods: Three hundred and seven consecutive patients who fulfilled the inclusion and exclusion criteria and presented with first MI were studied. All patients were divided into four groups according to the 6:00 hours interval of the day (Circadian rhythm). Group I comprised of patients presenting with onset of symptoms between 0-6 hours, Group II 6:01 to 12:00 hours, Group III 12:01 to 18:00 hours and Group IV 18:01 to 24:00 hours. Data was analyzed for variations within groups. Results: Two peaks of onset of symptoms were observed, first between 0-6 hours 144 (33.9%) patients and the second between 6:01 to 12:00 hours 87 (28.3%) and a non significant association was observed in time of onset of acute myocardial infarction P = 0.082. The trough was evening time 12:01 to 18:00 hours where only 63 (20.5%) patients had acute myocardial infarction. Mean age of study population was 56 ± 12.7 years. Mean age was similar in all the four groups P = 0.155. There were 228 (74.3%) males, 79 (25.5%) females. The circadian morning peak of MI symptom onset was attenuated in patients with diabetes as Group IV consisted of higher number 24 (37.5%) of diabetics followed by group I 23 (34.7%). Overall group II had the maximum number of hypertensive patients 41 (47.1%) as compared to other groups. Obesity was observed in 55 (18%) with similar number of patients in all groups P = 0.492. Majority of patients 117 (38.1%) presented between 4-8 hours after the onset of symptoms. Overall 170 (55.4%) patients had anterior wall myocardial infarction followed by inferior wall myocardial infarction in 82 (26.7%) patients. Conclusions: Our study demonstrates that the circadian morning peak of MI symptom onset was attenuated in patients with diabetes, suggesting a role of autonomic dysfunction. Inconsistency in observation of such an effect in patients with diabetes in the past may well have been due to differences in the duration of diabetes.