Prevalence of Right Atrial Impairment and Association with Outcomes in Cardiac Amyloidosis

Background: Cardiac amyloidosis (CA) is an infiltrative cardiomyopathy in which abnormally folded proteins deposit within the myocardium and the atrial walls. While left atrial dysfunction has been previously reported, the impact of CA on right atrial (RA) structure and function is unknown.

Methods: We retrospectively studied 118 patients (67 immunoglobulin light chain [AL-CA], 51 transthyretin [ATTR-CA]; age, 70 ± 12 years; 57% men) who underwent transthoracic echocardiogram in sinus rhythm. Right atrial reservoir, conduit, and booster strain were quantified using speckle-tracking and compared between patients with CA and 50 healthy age-, sex-, and race-matched controls using the chi-squared or Mann-Whitney test. The relationship between RA parameters and mortality was assessed using Cox regression.

Results: Right atrial volume was significantly larger in cases with CA compared with in controls: 29 (22-37) vs 21 (15-25) mL/m², P < .001. Right atrial reservoir (21% [14%-35%] vs 37% [34%-43%], P < .001), conduit 11% [18%-6%] vs 14% [11%-17%], P < .001), and booster (10% [17%-5%] vs 23% [20%-27%], P < .001) strains were all significantly more impaired in the CA group compared with controls. Compared with AL-CA, ATTR-CA patients had significantly larger RA volume (34 [26-44] vs 28 [20-35] mL/m², P = .005) and significantly more impaired RA reservoir (17% [10%-30%] vs 27% [17%-37%], P = .007), conduit (8% [13%-6%] vs 13% [20%-8%], P = .031), and booster (7% [14%-4%] vs 11% [18%-6%], P = .030) strain. Among CA patients, RA reservoir (hazard ratio = 0.97 per %, P = .006) and RA conduit (hazard ratio = 1.05 per %, P = .004) were significantly associated with mortality, while RA volume (P = .362) and RA booster strain (P = .180) were not.

Conclusions: In CA, abnormalities in RA size and strain are highly prevalent and associated with worse prognosis, suggesting the presence of intrinsic RA atriopathy. Right atrial strain appears to be a potentially useful marker in the diagnosis, subtype differentiation, and risk stratification of CA.