Abstract

MIRAGAYA, María Agustina  and  MAGRI², Osvaldo Federico. More convenient equation for predicting maximum heart rate expected in exercise testing. Insuf. card. [online]. 2016, vol.11, n.2, pp.56-61. ISSN 1852-3862.

Objective. To compare the maximum heart rate (HRmax) reached with the expected according to the classical formula (220 minus age) and that proposed by Tanaka [208,75 - (0,73 x age)] in different populations to determine which is the most accurate equation, given that this parameter is used to evaluate the chronotropic and coronary reserve. Material and method. Descriptive, observational and cross-sectional study with 910 patients who underwent exercise stress test graduated at the Medical Institute Rio Cuarto (Cordoba, Argentine) during 2012-2013. Åstrand protocol was used. HRmax achieved and expected of each patient by the classic formula and Tanaka's formula were evaluated. These results were compared by gender, age range, body mass index (BMI), presence of risk factors (hypertension, diabetes mellitus, dyslipidemia, previous coronary disease and/or smoking) and use of beta blockers. Microsoft Excel for statistical analysis and SPSS was used, and the statistical probability by Pearson index with a value <0.01. Results. The 910 patients, 554 (61%) of male and 356 (39%) female, mean age was 47±16 years, BMI was 27±5 were analyzed. The 48% of the population had one or more risk factors and 15% were treated with beta blockers. When analyzing the HRmax reached by the patient and compared with the expected according to both formulas, an overestimation was found by them, resulting in more accurate Tanaka's formula in the under 40 years and the classic formula those over 40 years. In patients with BMI >25 and in those treated with beta blockers, an overestimation of HRmax expected with both formulas was evidenced. Conclusions. Tanaka's formula was more accurate in patients younger than 40 years without sex differences, so we suggest using this equation for this population and reserve the classic formula for over 40 years. This relationship remained in subpopulations according to presence or absence of risk factors and BMI. These findings would have the effect of underestimating the true level of physical stress imposed during the stress test and the right intensity of exercise prescribed programs. The population using beta blockers showed an overestimation with both formulas, being more pronounced the younger was the patient.

Keywords : Maximum heart rate; Exercise stress test; Equation; Tanaka.

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