Objective: Ischemic heart disease is associated with high rates of mortality and it is the most prevalent among cardiovascular diseases. It is a multifactorial disease, and its prevention depends on control of risk factors. Resting electrocardiogram can be used to detect manifestations of ischemic heart disease, since some electrocardiographic abnormalities are indicative of coronary disease in asymptomatic subjects. The aim of the study was to analyze the relationship between electrocardiographic abnormalities and risk factors for ischemic heart disease in an adult population from the metropolitan area of São Paulo.
Methods: A cross-sectional study was carried out in an adult population (age 20 years and over) from Cotia, near São Paulo, southeastern of Brazil. The study population comprised 1067 subjects. The subjects were interviewed using a questionnaire. The variables studied were: gender, age, smoking behaviour, physical activity, body mass index, waist-to-hip ratio, blood pressure, diabetes mellitus, blood lipids (total cholesterol, LDL-cholesterol, HDL-cholesterol and triglycerides) and electrocardiographic abnormalities. Electrocardiographic abnormalities were grouped according to the classification: ST-T changes, left ventricular hypertrophy and abnormalities non related to ischemic myocardial disease or without abnormalities.
Results: The population was relatively -young (79% younger than 50 years, mean age 39.8 +/- 13.2 years old), and 59.3% were female. The resting electrocardiogram showed ST-T changes in 9.5% of the subjects and left ventricular hypertrophy in 3.3%. Female gender, age over 65 years for women and 55 years for men, diabetes, hypertension, total cholesterol >/= 200 mg/dl, LDL-cholesterol >/=130 mg/dl, Triglycerides >/=200 mg/dl, body mass index >/= 25 Kg/m2 and abnormal waist-to-hip ratio, were positively related to ST-T changes. Male gender, diabetes, hypertension and smoking behaviour were positively related to left ventricular hypertrophy. In the presence of ST-T changes on the ECG, we observed an odds ratio of 3.54 for the diagnosis of systolic hypertension an of 1.83 for total cholesterol >/= 200 mg/dl. In the presence of left ventricular hypertrophy on the ECG, we found an odds ratio of 5.92 for systolic hypertension diagnosis. Among the three most important risk factors correlated to electrocardiographic abnormalities indicative of myocardial ischemia, two can be controlled by nutritional intervention (hypertension and total cholesterol >/= 200 mg/dl). This findings suggest the importance of its early detection. Future studies should determine the predictive value of the electrocardiogram, a simple and inexpensive method, suggesting the presence of cardiovascular risk factors in epidemiological and nutritional studies.