Abstract
In recent studies from Sweden an increased prevalence of HLA-B27 associated diseases and of HLA-B27 was found in an unselected group of men with permanently implanted pacemakers and with a heart block. Furthermore, a significantly increased prevalence of HLA-B27 was found in men with a pacemaker who had no clinical or radiological signs of HLA-B27 associated disease. To obtain more insight into the association between HLA-B27 and heart block, and the possible role of HLA-B27 in causing this block, a study was made of 35 patients with a pacemaker and heart block of unknown cause, selected from a total group of 350 men with pacemakers who were still alive at the time of the study. One of these 35 men had ankylosing spondylitis and two patients had an asymptomatic sacroiliitis, but all three were HLA-B27 negative. HLA-B27 was present in five (14%) patients, which is a significantly higher prevalence than in healthy controls (17/292, 6%). This percentage is equal to the percentage of HLA-B27 positivity found in the Swedish study on unselected men with an implanted pacemaker, in whom the presence of an HLA-B27 associated disease had been excluded. It suggests that factors other than HLA-B27 are important in the pathogenesis of heart block in most patients.