[Reproducibility of electrophysiological tests of sinus node function in patients with sick sinus syndrome. Reproducibility of tests of sinus node recuperation time, corrected sinus node recuperation time and sino-atrial conduction time].

In order to clarify whether SNRT, CSNRT and SACT are reproducible tests, 20 patients with sick sinus syndrome underwent two successive electrophysiological studies with an interval of 24 hours; mean sinus cycle, SACT, SNRT, CSRNT were evaluated. Although no significant differences were found between the mean values of the two studies, in isolated cases remarkable variations of one or more parameters were observed. We conclude that SNRT, CSNRT and SACT are reproducible tests only if mean values in a large number of patients are considered, while they are not as useful in quantifying sinus node dysfunction in single cases. In conclusion, while SNRT, CSNRT and SACT are reproducible and useful in comparing data from relatively large number of patients, great caution should be used before drawing conclusions of potentially serious diagnostic and prognostic consequence in the single patient.