[Classification and prevalence of supraventricular tachyarrhythmia].

The prevalence of supraventricular tachyarrhythmias in the general population is still a debated issue. This appears mainly due to the few works in the literature which correctly deal with the complex methodologic aspects of such a research. Data are often taken from different populations, with different methods for data recording. Moreover Holter monitoring, the most employed recording technique, lacks the desired sensitivity to this aim. However recent reports suggest that the prevalence of supraventricular tachyarrhythmias is higher than commonly thought. The prevalence of supraventricular premature beats increases with aging: they are found in 10%-20% of subjects less than 20 years, in 30%-60% of those between 20 and 60 years, in 90% of subjects older than 75 years. They are few (generally less than 100/24 hours) in people without an evident heart disease. In the Framingham study the incidence of the atrial fibrillation is 1.7%; it increases with aging, and is very rare in young. In 60% of the cases it is chronic, and in 40% it is paroxysmal. The true prevalence of the ectopic atrial tachycardia is not known; however it is frequent in older subjects with various types of heart disease, with sick sinus syndrome, with chronic pulmonary disease. The reentrant paroxysmal supraventricular tachycardia is reported in about 1% in the general population. Electrophysiologic studies have shown that in 70% of cases the reentrant circuit is entirely localized in the A-V junction whereas in the remaining 30% a concealed Kent bundle with only retrograde conduction is involved.(ABSTRACT TRUNCATED AT 250 WORDS)