In 1930 Wolff, Parkinson and White1 described for the first time a syndrome characterized by an abnormal and distinctive type of electrocardiogram presented by healthy young people prone to paroxysmal tachycardia. Since then, more than two hundred articles on this syndrome have appeared in the literature. Most of these are reports of 1 or several cases, or deal with the mechanism of the abnormal electrocardiogram2 or with that of paroxysmal tachycardia,3 based on electrocardiographic analysis,3b the action of drugs,4 animal experimental investigation5 and histologic study in animals and man.6 Two extensive reviews of the literature have been published.7 There has, however, been little of a follow-up nature. In addition to the 11 cases reported in our original communication,1 we have seen 41 new cases, making a total of 52.
CLINICAL DATA
The clinical and electrocardiographic data of the new series are presented in table 1. There were 28