Background/Purpose:

Isolated Recurrent pericarditis (IRP) is a disease with high morbidity. IRP refers to recurrent pericarditis not associated with an autoimmune rheumatic disease or cardiac surgery/injury. Conventional therapy for IRP is a combination of NSAIDs, colchicine and Glucocorticoids (GC) termed triple therapy. A major cause of morbidity in these patients is the predictable side effects of prolonged GC therapy to prevent and treat flares. There is some evidence to support the use of azathioprine (AZA) as an immunomodulating agent in this setting.¹The purpose of our study was to evaluate whether AZA can be used as an effective steroid sparing agent in IRP. This goal was achieved by evaluating the average and cumulative GC requirement over 6 months before and after initiation of AZA in patients with IRP. 

Methods:

To be eligible for the study patients had to be followed for at least 6 months after initiating AZA and had to have at least 2 recurrences of IRP prior to initiation of AZA. After evaluating all patients with IRP, 13 patients satisfied the inclusion criteria. Patients’ charts were reviewed to determine the total dose of GC required in 2 week intervals over the course of 6 months. Each IRP flare (as defined by the cardiologist) was also documented. Since the onset of action of AZA is thought to be 2-3 months, the number of flares after starting AZA was documented between months 3 and 6. Paired t-tests and Wilcoxon rank sum tests were used for statistical analysis. All tests were performed at a significance level of 0.05. 

Results:

Twenty-eight patients were excluded because of evidence of systemic rheumatic disease or prior immunomodulator therapy. Out of 13 IRP cases, 10 were considered idiopathic or post viral and 3 were post myocardial injury. IRP patients had an average disease duration of 17 months prior to the initiation of AZA and all had at least 5 months of continuous prednisone use prior to initiation of AZA (12 patients had prednisone for >6 months). The mean daily dose of prednisone prior to AZA was 21 mg, and cumulative dose was 4,004 mg over 6 months. The mean daily dose of prednisone post AZA was 13 mg (p= 0.003), and cumulative dose was 2,229 mg (p=0.012) over 6 months. The average number of flares while on triple therapy in the 6 months prior to AZA was 3, and number of flares between months 3 and 6 of AZA therapy was 0.3 (p=0.001). The average dose of AZA was 1.8 mg/kg. Three patients were not able to lower their prednisone dose after AZA initiation and 2 of these patients were on < 1.5 mg/kg of AZA/day. 

Conclusion:

This is the first retrospective study that evaluated the average and cumulative dose requirement of GC in patients with IRP to maintain clinical remission before and after initiation of AZA. After the initiation of AZA, patients were able to have a significant reduction in the dose of GC required and had a significant reduction in the frequency of flares within a given time period.  In conclusion, this study suggests AZA is an effective steroid sparing agent in IRP. Further studies are needed to confirm these findings.

1. Vianello F, et al. Int J Cardiol. 2011 Mar 17;147(3):477-8

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/azathioprine-may-be-an-effective-steroid-sparing-agent-in-patients-with-isolated-recurrent-pericarditis/