[Wolff-Parkinson-White syndrome after 50 yars of age. Clinical and electrophysiological data].

The Wolff-Parkinson-White syndrome is usually observed in young people and is much rarer in patients over 50 years old. This fact may be explained by the demise of a certain number of patients before the age of 50 and/or a change in the clinical features of the syndrome with age and/or of the electrophysiological properties of the normal and accessory conduction pathways. To test the latter hypothesis, the clinical and electrophysiological data of 15 patients over 50 years old with the Wolff-Parkinson-White syndrome (Group I) were compared with that of 10 patients under 30 years old with the same syndrome (Group II). The same protocol of electrophysiological investigation was used in both groups of patients. The results showed a significant difference (p < 0.001) between the two groups in the incidence of associated cardiac disease. This was more common in Group I (1 4 out of 15 patients) than in Group II (2 out of 10 patients). The cardiothoracic ratio was significantly higher in Group I (p < 0.01). The two groups also differed in the age at which tachycardia first occured. 9 out of 11 patients in Group I only had symptoms after thirty years. On the other hand, there was no significant difference in the types of tachycardia and the frequency of attacks. There was no significant difference in QRS, PR, AH, HV intervals, in the ventriculo-atrial conduction time and the effective refractory periods of the atrium, right ventricle or atrio-ventricular node. There was no significant difference in the anterograde and retrograde refractory periods of the accessory pathways between the two groups. Reciprocating tachycardia, initiated by electrical stimulation in 7 patients in Group I and 6 patients in Group II, was conducted anterogradely to the ventricles through the normal pathway and retrogradely to the atria through the the accessory pathway. This study suggest that age-related changes in the electrophysiological properties of the accessory are not an important prognostic factor in the Wolff-Parkinson-White syndrome.