RESUMO
BACKGROUND: The normal sinus heart rate standard of 60 to 100 beats per minute was set by the NYHA(New York Heart Association) in 1928. It has long been accepted to physicians, but clinical studies and experience suggest that both these limits are too high. Thus we reexamined to define operationally normal sinus heart rate that are scientifically and clinically acceptable. METHODS: Total 1,930 subjects(aged 20 to 92 years) were analyzed and evaluated for age, sex, body mass index(BMI), systolic blood pressure, diastolic blood pressure, and resting heart rates by electrocardiogram. We used Pearson's correlation test and t-test to analyze these data. RESULTS: Among 1930 subjects, 982 cases were male(51%) and 948 cases were female (49%), whose mean age was 48 years in male and 51 years in female. For the entire sample, mean heart rate and standard deviation was 68 +/- 11 beats/min. There was statistically significant difference between male(67+/-11 beats/min) and female(68+/-10 beats/min)(P<0,05). The prevalence of sinus tachycardia and bradycardia, calculated by current normal standard of 60 to 100 beats/min, was 22.0% (424 cases) and 0.9% (18 cases). Mean +/- two standard deviation yields rounded extremes of 46 to 89 beats/min for normal sinus heart rate. A positive correlations between resting heart rate and age(r=0.11), systolic blood pressure(r =0.17), diastolic blood pressure(r=0.12) were found(P<0.01). CONCLUSIONS: Two extremes of the normal sinus heart rate standard of 60 to 100 beats/min are set too high. They result in lower sensitivity for tachycardia and lower specificity for bradycardia. We propose that normal range for sinus heart rate should be 50 to 90 beats/min which is statistically justified, more realistic for clinical investigation.