Influence of age, gender, and serum triglycerides on heart rate in a cohort of asymptomatic individuals without heart disease Roge ´rio Silva de Paula * , Ivana Antelmi, Marcos Antonio Vincenzi, Carmen D.S. Andre ´, Rinaldo Artes, Cesar Jose ´ Grupi, Alfredo Jose ´ Mansur Heart Institute (InCor), University of Sa ˜o Paulo Medical School, General Outpatient Clinics, Av. Dr. Ene ´as de Carvalho Aguiar, 44, Sa ˜o Paulo, 05403-000, Brazil Received 23 August 2004; accepted 13 November 2004 Available online 12 March 2005 Abstract Background: Age, sex and blood lipids were demonstrated in epidemiological studies to influence heart rate measured on physical examination, on 12-lead electrocardiogram or with automatic devices for short-term measurements. We hypothesized that in healthy individuals, age, sex and other clinical variables may also influence heart rate measured on 24-h ambulatory electrocardiographic monitoring. Methods: We studied 625 asymptomatic individuals with normal clinical examination, aged 15 to 83 (mean 42, standard deviation 11.9) years, 276 (44.2%) men and 349 (55.8%) women. Heart rate was evaluated on 24 h ambulatory electrocardiographic monitoring. Variables selected in univariate analysis (v 2 and Student t tests) were further submitted to multivariate analysis with canonical correlation to assess the strength of associations between heart rate and other variables, and multiple linear regression models to generate reference curves. Results: Age was the most significant influence on canonical variable of heart rate relative to other clinical and laboratory variables (0.55; p b0.01). There was an increase in the minimum heart rate and a decrease of maximum heart rate with increasing age in both genders. The increase was steeper in men and the decrease was steeper in women. Minimum heart rate increased with increasing serum triglycerides and decreased as estimated maximum oxygen consumption increased. Conclusions: There was a narrower variation of heart rate with increasing age in both genders in healthy individuals. This variation was less pronounced in women. In addition, status of body haemostasis associated with peculiar metabolic conditions expressed in serum triglycerides levels may also be associated with heart rate. D 2005 Elsevier Ireland Ltd. All rights reserved. Keywords: Heart rate; Ambulatory electrocardiographic monitoring; Ambulatory care; Preventive health service Epidemiological and clinical studies demonstrated that heart rate was an independent variable associated with cardiovascular mortality. Heart rate was evaluated either through pulse rate on physical examination [1,2], 12-lead electrocardiogram [3–6], short-term monitoring [7], or 24 h ambulatory electrocardiographic monitoring [8,9]. Heart rate was also demonstrated to be modulated by age [10– 12] and gender [12,13]. In addition, metabolic variables such as cholesterolemia and serum triglycerides [7] were also demonstrated to be related to heart rate [14]. Studies of heart rate with ambulatory electrocardio- graphic monitoring in healthy individuals relative to age and gender were performed in smaller samples, in the range between 37 and 191 participants [10,11,15–18], in restricted population strata [10,12,19–27] with different recording methods [15,19,28,29]. Higher resting heart rate was also demonstrated to be associated with increasing age and increasing blood pressure [14]. Studies of heart rate in healthy individuals may contrib- ute to the knowledge of the heart rate as a variable related to 0167-5273/$ - see front matter D 2005 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijcard.2004.11.023 T Corresponding author. Tel.: +55 11 3069 5237; fax: +55 11 5521 8749. E-mail address: casrspaula@incor.usp.br (R.S. de Paula). International Journal of Cardiology 105 (2005) 152 – 158 www.elsevier.com/locate/ijcard