Intramyocardial Inflammation Predicts Adverse Outcome in Patients with Cardiac AL Amyloidosis

Abstract Aims To evaluate the influence of endomyocardial biopsy (EMB)-proven intramyocardial inflammation on mortality in patients with cardiac transthyretin amyloid (ATTR) or amyloid light-chain (AL) amyloidosis. Methods and results We included 54 consecutive patients (mean age 68.83 ± 9.59 years; 45 men) with EMB-proven cardiac amyloidosis. We followed up patients from first diagnostic biopsy to as long as 36 months (mean 11.5 ± 12 months) and compared their outcome with information on all-cause mortality with or without proof of inflammation on EMB. Intramyocardial inflammation was assessed by quantitative immunohistology. Patients suffering from amyloidosis revealed a significant poor prognosis with proof of intramyocardial inflammation in contrast to those without inflammation (log-rank P = 0.019). Re-grouping of patients indicated AL amyloidosis to have a significant impact on all-cause mortality (log-rank P = 0.012). The detailed subgroup analysis showed that patients suffering from AL amyloidosis with intramyocardial inflammation have a significantly worse prognosis compared with AL amyloidosis without inflammation and ATTR with or without inflammation, respectively (log-rank P = 0.014, contingency Fisher's exact test, P = 0.008). Conclusion Our study reports for the first time a high incidence (48.1%) of intramyocardial inflammation in a series of patients with EMB-proven cardiac amyloidosis and could show that in patients with AL amyloidosis, intramyocardial inflammation correlated significantly with increased mortality. Our data have a direct clinical impact because one can hypothesize that additional immunomodulating/anti-inflammatory treatment regimens in patients with biopsy-proven inflammation of heart muscle tissue could be beneficial for patients suffering from cardiac AL amyloidosis.