RESUMEN
INTRODUCTION: The relation between heart rate and age during the exercise test is dependent on the altitude over the sea level in which the test is made. OBJECTIVE: To observe the behavior of the heart rate during a maximal exercise test and its relation to age and to the altitude of Mexico City. METHOD: Observational, non randomized study of 1,853 healthy subjects who underwent maximal exercise test done with Bruce's protocol, in the Department of Cardiology of the Spanish Hospital of Mexico City. RESULTS: The distribution by age groups showed a normal curve. They were divided by gender (67% males and 33% females) with a mean age of 47.6 +/- vs 49.6 +/- 13.7 years respectively (p = 0.003). Maximal heart rate according to gender (167.9 +/- 17.4 vs 160 +/- 18.2 bpm, p = 0.001). Trained vs sedentary (85.7% vs 14.3%). Maximal heart rate by grade of training (169.1 +/- 16.4 vs 167.6 +/- 17.8 bpm, p > 0.05) and the lineal correlation of maximal heart rate dependent on age of the subject (r-0.61, Y = 204.37 + (-0.810*X), p = 0.001). CONCLUSIONS: The maximal heart rate during maximal exercise test at the altitude of Mexico City is lower than those reported in the literature. This is statistically significant and depends on age and it does not bear any relationship to the degree of training, at least in our subgroup of subjects studied. The same is true for females and the dependence on age remains the same too.
Asunto(s)
Altitud , Prueba de Esfuerzo , Frecuencia Cardíaca/fisiología , Adolescente , Adulto , Distribución por Edad , Factores de Edad , Anciano , Análisis de Varianza , Femenino , Humanos , Masculino , México , Persona de Mediana Edad , Aptitud Física , Análisis de Regresión , Factores SexualesRESUMEN
INTRODUCTION: The calcium score (CS) of the coronary arteries by computed tomography (CT) is an useful procedure for the diagnosis of obstructive coronary disease (OCD), with an average sensitivity of 82 +/- 6%, specificity of 88 +/- 2%, positive predictive value (PPV) of 57 +/- 7% and negative predictive value (NPV) of 96 +/- 2%. The objective of this trial was to compare helicoidal CT Scan with the traditional method and define sensitivity, specificity, Positive predictive value and negative predictive value against the coronary angiography. METHODS: From June of 1998 to March of 1999, one hundred and sixty six patients with coronary arteries CT were studied. The CT was done with an ELSCINT-CT Twin equipment and a software for the quantification of the coronary arteries CS in Hounsfield units. In forty one, coronary angiography was performed. A significant obstructive lesion was defined as > or = 70% of luminal stenosis in at least one artery, or > or = 50% in the left main and > or = 50% if some other artery was involved. This group was divided in accordance to the CS in two subgroups: A with a CS < or = 150 and B those with a CS > or = 151. RESULTS: In group A, 45% had significative lesions vs 95% in group B (p = 0.001). The sensitivity was 65%, specificity 95%, PPV 64% and the NPV 92%. Relative risk 2.08 (CI 95% 1.38-3.54) and Odds ratio 21.6 (CI 95% 2.43-191.37). CONCLUSIONS: Even though the small sample, CT is an useful procedure for the diagnosis of the OCD.