BACKGROUND AND OBJECTIVES: The aim of this study is to analyze the presence of circadian rhythm in the time of onset of symptoms of acute myocardial infarction treated by a prehospital emergency system and the influence of modifiable cardiovascular risk factors and non-modifiable as modulators of that circadian rhythm. PATIENTS AND METHODS: Retrospective analysis of 709 patients clinically diagnosed with acute myocardial infarction on-site in the prehospital setting. The variables were time to onset of symptoms, age, sex, previous ischemic heart disease, hypertension, diabetes mellitus, hyperlipidemia and smoking. We analyzed the rhythm with cosinor multiple sinusoid method, with 3 harmonics (24, 12 and 8h) for the adjustment. RESULTS: The time of onset of pain showed circadian rhythm (P <,001), peaking at 10.39 and a valley at 4.28, showing a sinusoidal curve fitting bimodal aspect with a predominant morning peak and another evening one of lower amplitude. All subgroups categorized by the study variables showed circadian rhythm, with a cosine curve similar to the global infarction. Smokers had a predominantly evening peak. CONCLUSIONS: Acute myocardial infarction shows a circadian rhythm. Smoking and diabetes mellitus can modify the standard incidence rate of occurrence of myocardial infarction.
BACKGROUND AND OBJECTIVES: The aim of this study is to analyze the presence of circadian rhythm in the time of onset of symptoms of acute myocardial infarction treated by a prehospital emergency system and the influence of modifiable cardiovascular risk factors and non-modifiable as modulators of that circadian rhythm. PATIENTS AND METHODS: Retrospective analysis of 709 patients clinically diagnosed with acute myocardial infarction on-site in the prehospital setting. The variables were time to onset of symptoms, age, sex, previous ischemic heart disease, hypertension, diabetes mellitus, hyperlipidemia and smoking. We analyzed the rhythm with cosinor multiple sinusoid method, with 3 harmonics (24, 12 and 8h) for the adjustment. RESULTS: The time of onset of pain showed circadian rhythm (P <,001), peaking at 10.39 and a valley at 4.28, showing a sinusoidal curve fitting bimodal aspect with a predominant morning peak and another evening one of lower amplitude. All subgroups categorized by the study variables showed circadian rhythm, with a cosine curve similar to the global infarction. Smokers had a predominantly evening peak. CONCLUSIONS:Acute myocardial infarction shows a circadian rhythm. Smoking and diabetes mellitus can modify the standard incidence rate of occurrence of myocardial infarction.