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Arquivos Brasileiros de Cardiologia
On-line version ISSN 1678-4170
TEIXEIRA, Flávia P.; RICARDO, Djalma R.; CASTRO, Claudia Lucia Barros de and ARAUJO, Claudio Gil S. de. Evaluating cardiac vagal activity on a conventional electrocardiogram. Arq. Bras. Cardiol. [online]. 2007, vol.88, n.4, pp. 378-383. ISSN 1678-4170. http://dx.doi.org/10.1590/S0066-782X2007000400002.
OBJECTIVE: To determine the viability of using a conventional electrocardiogram (ECG) tracing for assessment of CVA. METHODS: We retrospectively analyzed 1395 individuals (995 males), aged 46 ± 17.2 years (mean ± standard deviation) with conventional ECG tracings to measure the delta RR (which represents the difference in milliseconds (ms) between the greatest and smallest RR interval) and results of a second autonomic parasympathetic evaluation, the 4-second exercise test (T4s), that quantifies CVA by the cardiac vagal index (CVI). ROC curves were obtained to determine the values of Delta RR for a closer correlation with sensitivity and specificity for 1.20 and 1.95 ms, the low and high CVA cutoff points, respectively. RESULTS: The delta RR levels correlated significantly with those of the CVI (r=0.40; p<0.001). We identified < 60 and > 120 ms as the best cutoff points for low and high CVA. Sensitivity was 75% and 57%, specificity was 62% and 79%, and the areas of the ROC curves were 0.76 and 0.74, respectively. CONCLUSION: The visual measurement of delta RR on an ECG tracing seems to be a valid quick preliminary clinical evaluation of CVA and can be useful in medical offices, emergency units, or situations in which the use of more sophisticated methods may not be feasible, appropriate, or convenient.
Keywords : Exercise test; electrocardiography; heart rate.