Wolff-Parkinson-White (WPW) syndrome is associated with atrioventricular re-entrant tachycardia, but a patient showing a pre-excitation syndrome on electrocardiogram (ECG) may remain asymptomatic. The main problem is that some of these asymptomatic patients or patients with re-entrant tachycardia are at risk of sudden death.1 The studies of patients with aborted sudden death indicated that in most of these patients atrial fibrillation with a rapid conduction over the accessory pathway is the main finding. The risk of sudden death was reported as being relatively high (1.5%) in studies of symptomatic patients2,3 and lower in asymptomatic patients.4,5
Asymptomatic cohorts frequently considered relatively young people. Fitzsimmons et al.6 studied aviators and reported a sudden cardiac death risk of 0.02% per patient per year. However, among patients resuscitated from sudden death,7–9 ventricular fibrillation was the first manifestation of the WPW syndrome in 26 and 53%, respectively, of their series. Studies by Pappone et al. have confirmed the value of evaluating asymptomatic subjects, but their investigations involved only subjects below 35 years of age.10,11 Therefore, assessing children and young adults for WPW syndrome is recommended because of the risk of sudden death linked to this condition. There have been few studies involving older subjects with WPW syndrome, because elderly patients are generally considered to have a lower risk of serious events and because other heart diseases such as arrhythmia, hypertension, coronary heart disease, valvular disease or heart failure are more frequent than WPW syndrome. However, some studies indicate that a risk of life-threatening arrhythmias remains present in asymptomatic12 and symptomatic elderly patients with WPW syndrome.13 Therefore, when we identify WPW syndrome in the elderly, its management is debated. A recent study by our centre13 reported similar clinical and electrophysiological data in adults and patients over 60 years of age (see Table 1).
Prevalence of Wolff-Parkinson-White Syndrome According to the Age of the Patient
WPW syndrome is present in 0.1–0.5% of the total population.14,15 Its prevalence is higher in young children because the pattern of the syndrome can disappear spontaneously before 12 years of age, 16 mainly when the accessory pathway refractory period is long.17
When the refractory period is short, the spontaneous changes are rare and there is a stability of findings in children over 12 years of age and in adults with inducible supraventricular tachycardia.18 The prevalence of WPW syndrome has been determined in young adults,15 and its real prevalence in elderly subjects is unknown because these patients frequently have other heart diseases. In the centre, 7% of the individuals with WPW syndrome were over 60 years of age.13
Younger patients can be asymptomatic and syncope may be the first event.13,19 The presumed mechanisms of syncope are not considered to be age-related;20 syncope may be independent of WPW syndrome, but generally is directly related to the syndrome and provoked by a re-entrant tachycardia or a rapid atrial tachyarrhythmia. Re-entrant tachycardia is often poorly tolerated because it is rapid or associated with heart disease. This causes syncope, an acute ischaemic event or acute heart failure.13 Tachycardia-related cardiomyopathy is seen frequently in elderly patients.
The risk of atrial fibrillation increases in elderly patients, hence the risk of a first episode of rapid atrial fibrillation. Therefore, a life-threatening arrhythmia might be the first event of WPW syndrome.21,22 A rapid atrial tachycardia or fibrillation conducted through the accessory pathway is rare, and diagnosis is frequently missed. In elderly patients, ventricular arrhythmias are more frequent. In addition, the precipitating factors differ from those in younger patients. High-level sporting activity is rare in the elderly, but other causes of adrenergic tone increases might be encountered. For example, surgery was the cause of the development of a ventricular fibrillation in a 72-year-old asymptomatic patient, and a Sunday dance was the cause of rapid atrial fibrillation with syncope in another (see Figure 1). In one patient, rapid atrial fibrillation was an adverse event related to treatment with verapamil.
The diagnostic value of non-invasive studies is low. ECG usually indicates signs in favour of a left lateral bundle of Kent, which seems to be the most frequent location in the elderly13 and is not helpful for prognostic evaluation.
Exercise testing is recommended in the evaluation of WPW syndrome,23 but it is rare to note an abrupt disappearance of WPW syndrome in favour of a benign form. The WPW pattern can be misdiagnosed, and false-positives from ECG on exercise are common. Electrophysiological study is the most reliable method of establishing the prognosis of WPW syndrome.24 The study can be performed by the transoesophageal13 or intracardiac route.25 The first route is indicated in asymptomatic patients, and the second in symptomatic patients to perform catheter ablation of the accessory pathway a second time. The end-points of the study are the determination of accessory pathway refractory period and the evaluation of the induction of re-entrant tachycardia and atrial fibrillation in the basal state and in adrenergic situations generally reproduced by isoproterenol infusion.24 At the end of the protocol, using the following definitions the prognosis of WPW syndrome can be established. WPW syndrome is considered to represent a risk of sudden death when the following association is observed: sustained atrial fibrillation is induced and the shortest respiratory rate (RR) interval between pre-excited beats is less than 250ms in the control state in adults or less than 200ms during isoproterenol infusion.
The shortest atrial pacing cycle length with 1=1 anterograde conduction via the bypass tract increases progressively with age.12,25–28 The effective refractory period of the accessory pathway increases with age,25–28 but the risk of atrial fibrillation also increases, hence the risk of a first episode of rapid atrial fibrillation, as seen in four elderly patients with WPW syndrome in the population we studied. The propensity for atrial fibrillation was shown to be higher in older patients compared with younger patients.12,25,29,30 Although the exact mechanism is uncertain, the risk of atrial fibrillation increases with the risk of associated heart disease,29 or may be associated with degenerative changes. The dispersion of atrial refractoriness was also shown to increase progressively with age.25,29 Therefore, the prevalence of a potentially malignant form of WPW syndrome in asymptomatic subjects does not decrease significantly with age.12Figure 1 reports the findings of an electrophysiological study performed in an asymptomatic 76-year-old subject. He presented a syncope related to a spontaneous atrial tachycardia at 76 years of age.
With an increase in sport in all age ranges, the risk of occurrence of a potentially severe arrhythmia in an asymptomatic WPW syndrome patient should not be underestimated. The reliability and simplicity of a transoesophageal study of WPW syndrome permits easy detection of those at risk of severe arrhythmia.
Management of Elderly Patients with Wolff-Parkinson-White Syndrome
Taking into account the possible risks linked to this condition, it is important to carry out investigations such as exercise testing and electrophysiological study for WPW syndrome, irrespective of the age of a subject, even if they are asymptomatic, particularly if the patient continues to exercise or needs to undergo extensive surgery. Prescription of drugs such as calcium antagonists or digoxin is contraindicated in these subjects without evaluation of the electrophysiological characteristics of the accessory pathway.31 Radiofrequency ablation, which is currently the recommended technique in symptomatic subjects and patients with a potentially serious form of WPW syndrome,11 is particularly interesting in elderly subjects, in whom tachycardia is often poorly tolerated, especially if it is associated with underlying heat disease. Nevertheless, due to the left lateral location, retrograde access is sometimes complicated if the aorta is particularly atheromatous with a high risk of arterial emboli.13,27 In addition, there is a risk of recurrence of atrial fibrillation after ablation of the bundle of Kent.32,33 The recurrence rate of paroxysmal atrial fibrillation after successful radiofrequency ablation of accessory pathways shows an age-related increase, being low in patients under 50 years of age (12%) and high in the older patients: 35% in patients over 50 years of age and 55% in patients over 60 years of age.32 These results have significant therapeutic implications concerning the decisions for pharmacological therapy after successful ablation in patients over 50 years of age. In addition, these data will help physicians to advise older patients properly about the risk of recurrence of atrial fibrillation after ablation.
When catheter ablation is not possible or is unsuccessful, the patient is treated with beta-blockers and/or antiarrhythmic drugs at a dosage adapted to the patient’s age. Flecainide, which is the drug recommended in children and adults, is indicated if there is no associated heart disease, which is a frequent condition in the elderly.34 The drug increases the accessory pathway refractory period34 and decreases the risk of atrial fibrillation.35 In the case of heart disease, amiodarone should be preferred.36 The effects of class I and III antiarrhythmic drugs decrease after isoproterenol administration or with exercise,37,38 and the association with beta-blockers is required in patients with arrhythmias related to an accessory pathway with a short refractory period.
In conclusion, WPW syndrome can be observed in subjects over 60 years of age. Although the incidence of WPW syndrome is low compared with the high number of coronary heart disease or heart failure patients, this syndrome is often due to the presence of a left lateral accessory pathway that may have retained its rapid conduction properties. We therefore recommend systematic examination, particularly if the patient continues to play sport or needs to undergo complex surgery. Ablation of the accessory pathway is indicated as soon as the patient becomes symptomatic, but this should be performed carefully due to the difficulty of accessing a left bundle of Kent.