[Third degree atrioventricular block.].

OBJECTIVE

Third degree atrioventricular block is considered present when none of the atrial impulses are conducted to the ventricles because of a disruption in the conducting system. Third degree atrioventricular block is usually considered a serious sign but most studies have been performed on hospitalized patients or certain professional groups. The objective of this study was to find the prevalence of third degree atrioventricular block in a representative population sample and estimate its prognostic significance.

MATERIAL AND

METHODS

In the Reykjavik Study, a prospective cardiovascular population study, 9139 men and 9773 women aged 33-79 years were exam notined in 1967-1991. A standard electrocardiogram was taken from all persons examined and coded according to the Minnesota code.

RESULTS

Third degree atrioventricular block was found in 11 persons, seven males and four females, an overall prevalence of 0.04%. All these individuals had signs of arrythmia on electrocardiograms taken later, and in addition some other heart disease. The heart block was temporary in seven individuals (64%) but six (55%) needed a pacemaker.

CONCLUSIONS

The prevalence of third degree atrioventricular block in this general population was low but nevertheless considerably higher than previously reported. The block was temporary in the majority of subjects. All had some underlying heart disease which seemed to affect the prognosis more than the heart block. In this survey fewer subjects than expected were found to need a pacemaker.