Circadian periodicity in the onset of acute ST segment elevation

ABSTRACT

To analyze the influence of diabetes mellitus on circadian rhythm affecting the onset of acute ST elevation myocardial infarction. Observational study. February to August 2010. Faisalabad Institute of Cardiology, Faisalabad. 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 600 hours interval of the day [Circadian rhythm]. Group I comprised of patients presenting with onset of symptoms between 0-6 hours, Group II 601 to 1200 hours, Group III 1201 to 1800 hours and Group IV 1801 to 2400 hours. Data was analyzed for variations within groups. Two peaks of onset of symptoms were observed, first between 0-6 hours 144 [33.9%] patients and the second between 601 to 1200 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 1201 to 1800 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. 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