The myocardium in ankylosing spondylitis. A clinical, echocardiographic, and histopathological study

Myocardial dysfunction in ankylosing spondylitis

Echocardiographic evidence has suggested abnormalities of the myocardial function in patients with ankylosing spondylitis. In this work the cardiac function in patients with ankylosing spondylitis and in normal volunteers was evaluated. Twenty four normal volunteers and 21 patients with ankylosing spondylitis aged 18-45 were studied. None had overt cardiac disease. Cardiac function was assessed at rest with echocardiography, at rest and during supine bicycle exercise using radionuclide angiography in the left anterior oblique position following equilibration with 740 MBq of technetium-99. The subjects undertook supine bicycle exercise with 30 W increments every three minutes to the point of fatigue. Comparison of data from normal volunteers and patients with ankylosing spondylitis were made using Student's t test for independent samples or the Mann-Whitney non-parametric technique, as appropriate. Subjects were matched for age, sex, height, and weight. There were no echocardiographic differences; however, global nuclide left ventricular function showed several differences between normal volunteers and patients with ankylosing spondylitis. The peak filling rate during exercise was significantly lower in patients with ankylosing spondylitis: normal volunteers 6.5 (SD 1.2); patients with ankylosing spondylitis 5.7 (1.2). The time to reach peak filling during exercise was significantly lower in patients with ankylosing spondylitis: normal volunteers 102 (22); patients with ankylosing spondylitis 120 (23). Regional analysis also showed differences between patients with ankylosing spondylitis and normal volunteers both at rest and during exercise. In the anteroseptal region the filling fraction and peak filling rate were significantly lower in patients with ankylosing spondylitis. Most of the differences (although not all) were in the variables of diastolic function. This study shows that there are subtle abnormalities in cardiac function in patients with ankylosing spondylitis. The major abnormalities are in the diastolic function, suggesting a decrease in left ventricular compliance.

Paraspinal muscle fibrosis: a specific pathological component in ankylosing spondylitis

The histological appearance of percutaneous superficial paraspinal muscle biopsy specimens from eight patients with ankylosing spondylitis was compared with that of biopsy specimens from 13 control patients with similar degrees of disability and spinal immobility due to severe, chronic mechanical back pain. In both groups marked type II muscle fibre atrophy was shown. Additionally, in patients with ankylosing spondylitis there were obvious increases in perifibre connective tissue in association with central migration of cell nuclei but without evidence of inflammation. Qualitative electromyography failed to show denervation changes in either group. Paraspinal muscle fibrosis, occurring over and above atrophic changes due to disuse, seems to be a specific pathological component of ankylosing spondylitis which may be of particular importance in early disease as it may contribute towards back stiffness and weakness.

Heart conduction disturbance: an HLA-B27 associated disease

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.

Platelet aggregating activity in serum from patients with HLA-B27 associated rheumatic and cardiac disorders: a possible link to the proliferative vascular changes

OBJECTIVE

To search for possible serum factors (immunochemical abnormalities) that reflect HLA-B27 associated inflammatory process with the proliferative endarteritis, which is an important cause of severe bradycardia and aortic valve regurgitation.

PATIENTS AND METHODS

Seventy four men with pacemakers were studied: 24 were HLA-B27 positive and had associated rheumatic and cardiac disorders, 13 were B27 positive but had no clinical or radiographic signs of a related rheumatic condition, and 37 were B27 negative controls. Randomly obtained serum samples were examined for a series of serum factors.

RESULTS

Thirteen (57%) of the 23 patients with HLA-B27 and associated rheumatic and cardiac conditions had platelet aggregating activity in their serum. No such activity was found in sera from patients in the other groups. None the less, immunochemical abnormalities were common among patients of all groups; 30 (41%) had antinuclear antibodies or rheumatoid factor or both.

CONCLUSION

The platelet aggregating activity found in patients with HLA-B27 and associated rheumatic and cardiac conditions may reflect serum factors that increase the stickiness of platelets and increase their adhesion to the vessel wall. This suggests a link via release of platelet derived growth factor(s) with the characteristic histopathological feature of proliferative endarteritis. Immunochemical abnormalities were common in serum from all men with pacemakers.

Echocardiographic diastolic abnormalities of the left ventricle in inflammatory joint disease

Echocardiographic early diastolic abnormalities have been shown recently in 50% of men with ankylosing spondylitis. Similar techniques were used to investigate subjects with rheumatoid arthritis and psoriatic arthritis with or without spondylitis. These subjects had no clinical, radiographic, or electrocardiographic evidence of cardiac or respiratory disease. Echocardiographic abnormalities seen resembled those of ankylosing spondylitis in that the interval between minimum left ventricular dimension and mitral valve opening was prolonged in 12 of 22 subjects with rheumatoid arthritis and in seven of 11 subjects with psoriatic arthritis. Isovolumic relaxation time was significantly prolonged in four subjects with rheumatoid arthritis and one with psoriatic arthritis. Unlike ankylosing spondylitis, however, there was consistent reduction in peak rate of left ventricular dimension increase in subjects with rheumatoid arthritis and psoriatic arthritis. In addition, the dimension increase during atrial systole was greater than normal in nine subjects with rheumatoid arthritis and two with psoriatic arthritis. The most likely cause of these abnormalities is increased connective tissue deposition in the myocardium.

Spontaneous inflammatory disease in transgenic rats expressing HLA-B27 and human beta 2m: an animal model of HLA-B27-associated human disorders

Humans who have inherited the human class I major histocompatibility allele HLA-B27 have a markedly increased risk of developing the multi-organ system diseases termed spondyloarthropathies. To investigate the role of B27 in these disorders, we introduced the B27 and human beta 2-microglobulin genes into rats, a species known to be quite susceptible to experimentally induced inflammatory disease. Rats from one transgenic line spontaneously developed inflammatory disease involving the gastrointestinal tract, peripheral and vertebral joints, male genital tract, skin, nails, and heart. This pattern of organ system involvement showed a striking resemblance to the B27-associated human disorders. These results establish that B27 plays a central role in the pathogenesis of the multi-organ system processes of the spondyloarthropathies. Elucidation of the role of B27 should be facilitated by this transgenic model.

Cardiac alterations in ankylosing spondylitis

Forty patients, 30 men and 10 women with an average age of 38.47 +/- 11.07 years, suffering from ankylosing spondylitis and attending a Rheumatology Outpatient Clinic, were evaluated for cardiovascular involvement. The evaluation was based on patients' clinical observation, electrocardiography, echocardiography, and chest x-ray. More than a simple review, this study was undertaken with the aim of arriving at a better clinical definition of the cardiovascular manifestations found in ankylosing spondylitis. In fact, of the 40 patients, 8 (20%) had systemic hypertension for which an explanation could not be found, 4 of whom were less than forty-five years old; the echocardiogram showed mitral valve prolapse in 4 patients (10%), 2 of them with a systolic murmur and other 2 with a protosystolic click on auscultation. More significant than the changes in conduction was the finding of a sinus bradycardia in 9 patients (22.5%), and a PR interval below 120 msec in 3 patients (7.5%). The authors conclude that the extension of cardiovascular changes in ankylosing spondylitis is more vast than usually acknowledged.