Background/Purpose Rheumatoid arthritis (RA) is one of the major causes of amyloid A (AA) amyloidosis. The major organs affected are the kidneys and gastrointestinal (GI) tract. Although cardiac amyloidosis is the principal cause of death in patients with amyloid L amyloidosis, significant cardiac involvement in AA amyloidosis is thought to be rare. On the other hand, the survival rate of hemodialysis patients with AA amyloidosis associated with RA has been shown to be low, and our previous study revealed that cardiac failure accounted for more than half of the mortality in these patients. The purpose of this analysis was to clarify the cardiac involvement and its clinical significance in patients with RA-associated AA amyloidosis.

Methods Twenty-seven RA patients (4 males, 23 females) with AA amyloidosis who were followed up at Niigata Rheumatic Center between April 2007 and March 2014 were enrolled. Each patient fulfilled the 1987 American College of Rheumatology criteria for RA. All patients had undergone GI tract biopsies, and had been confirmed to have reactive AA amyloidosis by pathological examination. The patients’ background data and echocardiographic features were analyzed retrospectively. Differences were assessed by Mann-Whitney U test*, Fisher’s exact test^#, and log rank test**, and differences at p <0.05 were considered statistically significant.

Results The median age was 71 [range, 48-89] yr, the period between the onset of RA and echocardiographic examination was 20 [2-41] yr, and the period between the onset of AA amyloidosis and echocardiographic examination was 1007 [20-6458] day. Echocardiography showed that the left ventricular (LV) posterior wall thickness was 11.0 [7.4-17.0] mm, with an interventricular septal thickness of 10.5 [5.5-14.2] mm, and an ejection fraction (EF) of 72.1% [32.3-85.4%]. Thirteen patients with LV wall thickness exceeded 11.0 mm were assigned to a LV hypertrophy (LVH) group, and their clinical features were compared with a normal group (n=14). Fatalities in the LVH group vs normal group were 7 vs 0 at two year after echocardiography and 9 vs 2 at the last observation. Kaplan-Meier survival curves showed a significant association with reduced survival in the LVH group (p=0.039**). There were no significant differences between the LVH group and the normal group at the baseline in terms of patient age (p=0.512*), duration of RA (p=0.627*), serum albumin level (p=0.92*), estimated glomerular filtration rate (eGFR) (p=0.094*), disease activity score in 28 Joints based on erythrocyte sedimentation rate (p=0.19*), modified Health Assessment Questionnaire score (p=0.77*), and echocardiogram EF (p=0.21*). Patients in the LVH group had a higher systolic blood pressure (133 [116-160] vs 120.5 [110-142] mmHg, p=0.039*), in spite of higher usage of antihypertensive agents (12 vs 3, respectively, p<0.001^#). Although the LVH group appeared to have a lower eGFR, there was no significant difference in survival rate between the patients whose eGFR was under 45 ml/min/1.73 m² (n=12) and the others (n=15) (p=0.52**).

Conclusion Thickening of the LV wall is a notable cardiac feature of patients with AA amyloidosis and is strongly suspected to contribute to their poor prognosis.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/analysis-of-cardiac-involvement-in-patients-with-amyloid-a-aa-amyloidosis-due-to-rheumatoidarthritis/