Background/Purpose:  Systemic rheumatic diseases (SRDs) are associated with increased cardiovascular (CV) morbidity due to accelerated atherosclerosis. However, SRDs are associated also with cardiac vasculitis that may contribute to the increased CV risk (1). The objective is to examine the occurrence and extent of inflammatory cell infiltrates (ICI) and small vessel vasculitis in all layers of the right atrium (epicardium, myocardium and endocardium) in patients with coronary artery disease (CAD) with and without SRDs.

Methods:  We examined biopsies from the right atrium taken in a standardized way during coronary artery bypass grafting from the edge of the openings for cannulation due to extracorporeal circulation from patients with and without SRD (matched for age, sex and acute coronary syndrome) included in Feiring Heart Biopsy Study (2). The specimens were fixed with paraffin and stained by hematoxylin and eosin, and one 3-mm thick section from each specimen was examined by light microscopy in a blinded manner.  The number and extent of ICIs in the three layers of the heart wall were semi-quantified.

Results:

	IRD (n = 40)	Non-IRD (n = 48)	Fisher mid-p test
Age, mean ± SD (years)	66,83 ± 10,5	66,42 ± 10,2	0.85
Male (%)	27 (67,5)	28 (58,3)	0.39
ICIs of epicardium (%)	24 (60%)	27 (56,2)	0.75
ICIs of myocardium (%)	0 (0%)	3 (6,2%)	0.17
ICIs of endocardium (%)	0 (0%)	1 (2,1%)	0.73
Vasculitis (%)	0 (0%)	0 (0%)	1.00

The infiltrates consisted predominantly of lymphocytes. Perivascular infiltrates occurred in all patients except for one. All the infiltrates in the myocardium were perivascular. There was no significant difference in the scores for the size and number of ICIs in the epicardium between the groups.

Conclusion:  In patients with CAD, vasculitis was not observed, but the occurrence of ICIs in the right atrium was high, mostly localized around small vessels. The ICIs were found predominantly in the epicardium, and the occurrence and extent of epicardial ICIs was similar in SRD and non-SRD patients. In the myocardium and endocardium, the ICIs occurred in a low frequency, and in the non-SRD group only (but the difference was not statistically significant). In theory, the observed ICIs might be secondary to or independent of cardiovascular disease (CVD), but the inflammation might also contribute to CAD by compromising of the function of epicardial coronary arteries. Interestingly, abnormalities in epicardium (increased mass of epiicardial adipose tissue) are related to CV prognosis, and we propose that inflammation in the epicardium might be of particular importance. Our findings do not support the hypothesis that inflammation in the heart including small vessel cardiac vasculitis is more common in SRD than non-SRD patients. However, this possibility cannot be completely ruled out as the number of examined specimens were small, taken from apparently healthy tissue, and the right atrium was the only site sampled.

References:
(1) Bely M, Apathy A. Orv Hetil 1996; 137(29):1571-8
(2) Hollan I et al. Arthritis Rheum 2007; 56: 20072-9

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/inflammatory-cell-infiltrates-in-the-heart-of-patients-with-coronary-artery-disease-with-and-without-inflammatory-rheumatic-disease-a-biopsy-study/