[Prevalence and course of Wolf-Parkinson-White syndrome in a population of 138,048 subjects]. / Prévalence et évolution du syndrome de Wolff-Parkinson-White dans une population de 138 048 sujets.

The prevalence of the Wolff-Parkinson-White (WPW) syndrome, frequency of arrhythmias and their evolution were studied in a group of volunteers consisting in 79,978 men and 59,070 women, aged from 20 to over 70. The higher prevalence of WPW in men than in women (p less than 0.001) decreased significantly with age, much more in men (p less than 0.001) than in women (p less than 0.05). Ventricular pre-excitation was intermittent in 6.7 p. 100 of men and in 16 p. 100 of women. The probable site of pre-excitation, determined on the orientation of the delta wave was more often left than right (104 vs 66, p less than 0.02). The frequency of paroxysmal tachycardia increased with age: 10 p. 100 of the cases from 20 to 39 years of age, 29 p. 100 from 40 to 59, 36 p. 100 at 60 and over (p = 0.05). It was 1.7 times more frequent in cases of left pre-excitation. A hundred and fifty-one patients were followed-up from 1 to 11 years (4.6): 5 patients died, 3 of non-cardiac and 2 of undetermined causes, with one sudden death in a 29 year old man. Fifty-three patients were reviewed 4.5 years after the initial examination: 9 pre-excitations (7 right, 2 left) had disappeared. In conclusion, the higher prevalence of WPW in men decreases with age. This decrease appears to be essentially due to the disappearance of the ventricular pre-excitation and not to an increased mortality. Arrhythmias are more frequent in older patients with left-sided pre-excitation.

[Prevalence and electrocardiographic forms of the Wolff-Parkinson-White syndrome]. / Prévalence et formes électrocardiographiques du syndrome de Wolff-Parkinson-White.

In a routine electrocardiographic study of 133929 subjects aged from 20 to 73, 136 cases of the Wolff-Parkinson-White syndrome were detected, 6 with intermittent pre-excitation. In this study, the prevelance of WPW was about 1 in a 1000, the highest incidence being in the 20-40 year age group with an equal sex ratio. The ECG analysis of the 136 cases consisted in determining the orientation of the delta wave in the precordial leads to establish the right or left ventricular origin of the pre-excitation, calculating the direction of the delta wave vector in the frontal plane to find out the anterior, lateral or posterior origin of the pre-excitation and analyse the position of the QRS axis to assess the appearances of the latest ventricular activity. The 136 ECGs were then classified according to electrophysiological criteria and the results of mapping: 1. Left ventricular pre-excitation; 74 cases characterised by a dominant delta wave in the right precordial leads. These cases were subdivided into: - 30 cases with posterior paraseptal pre-excitation, axis of the delta wave deviated superiorly and to the left, between -30 degrees and -60 degrees; - 20 cases of lateral pre-excitation with the vector of the delta wave deviated inferiorly and to the right between +100 degrees and +120 degrees; - 24 cases of anterior paraseptal pre-excitation with high amplitude delta and QRS deflections in all precordial leads and a delta wave axis between +50 degrees and +80 degrees. 2. Right ventricular pre-excitation; 62 cases characterised by a negative or isoelectric delta wave in the right precordial leads, including: - 14 posterior paraseptal pre-excitation with significant delta wave axis deviation between -30 degrees and -60 degrees; - 33 lateral pre-excitation with the delta and QRS axis pointing directly to the left at about 0 degrees; - 15 cases of anterior paraseptal pre-excitation with the delta wave axis between +50 degrees and +80 degrees. The cases with terminal forces of left ventricular activation in the same direction as the delta wave, superiorly and to the left at -60 degrees or inferiorly and to the right at +120 degrees, forming a single deflection of over 0,12 seconds' duration, are the result of delayed activation of the anterior or posterior fascicle of the left bundle after a long delay. On the other hand, the cases in which the direction of the pre-excitation is the same but the final part of ventricular activation moves away from the delta are probably the result of tension between the activation of the normal and accessory pathways.