Abstract 16808: Inflammasome Formation in Acute, Subacute and Chronic Myocarditis

Abstract

Background: Myocarditis is a syndrome of inflammation resulting in myocardial injury. The inflammasome is formed in response to injury and may lead to further injury and fibrosis. We assessed for differences in inflammasome formation in patients with biopsy-proven myocarditis myocarditis (>90 days of symptoms onset) as acute (<30 days), subacute (31-90 days), chronic myocarditis. Methods: We studied inflammasome formation by immunofluorescence for the scaffold protein of the inflammasome, apoptosis-associated speck-like protein containing a caspase-recruitment domain (ASC), in 23 patients with biopsy-proven lymphocytic myocarditis. The number of inflammasome (cells with ASC aggregates) were counted in random high-power fields (x40). Clinical data, including the duration of symptoms, was retrieved from the Cardiomyopathy Registry. Data are presented as N [%] or median [interquartile range]. Differences between groups were assessed with Kruskal-Wallis test and correlations with Spearman test. Results: Of the 23 patients (13 [56%] males, 45 [36-52] years of age), 9 were studied during the acute phase (10 [1-20] days), 7 in the subacute phase (60 [40-67] days) and 7 during the chronic phases (150 [150-180] days). Inflammasome formation was detected in all 23 (100%) patients. We found no statistically significant differences in the total number of inflammasomes comparing acute, subacute, and chronic myocarditis (8.2 [4.2-15.5], 6.2 [3.1-22.0], 5.0 [3.7-23.0], and respectively, P=0.99, Figure), and no statistically significant correlation between the duration of symptoms and inflammasomes (R=-0.37; P=0.87). Conclusions: Patients with biopsy-proven myocarditis show persistent inflammasome formation over a range of time from symptom onset, with no significant difference between acute, subacute and chronic presentation. Further studies are needed to determine whether the inflammasome contributes to ongoing injury in patients with myocarditis.