Left atrial remodeling and the prognostic value of feature tracking derived left atrial strain in patients with light-chain amyloidosis: a cardiovascular magnetic resonance study

Systemic light-chain (AL) amyloidosis is characterized by the aggregation of misfolded immunoglobulin light chain, predominantly infiltrating in the heart, including left atrium (LA). LA remodeling, such as increased interatrial septal thickness and enlarged size, has been observed. However, LA strain assessed by cardiac magnetic resonance feature tracking (CMR-FT) and its prognostic role remains to be further determined. Using CMR, the current study sought to investigate the characteristic of LA remodeling and the prognostic value of LA strain in patients with AL. Eighty-seven consecutive patients who underwent CMR with histologically confirmed systemic light-chain amyloidosis were retrospectively enrolled. LA strain parameters were analyzed based on CMR-FT algorithm. Amyloid infiltration and burden loads were assessed with CMR late gadolinium enhancement (LGE) and extracellular volume (ECV). Patients were categorized according to the extent of amyloid infiltration in cardiac myocardium. The primary endpoint was defined as all-cause mortality. The prognosis value of LA strain indices was evaluated using Cox proportional hazards regression and Kaplan-Meier curves. Interatrial septal thickness (3 [2-5] vs. 4 [3-5] mm, p = 0.007) and indexed LA volume (34.6 [26.9-44.6] vs. 50.5 [36.1-58.5] ml/m(2), p = 0.001) were significantly higher in patients with atrial involvement (LA-LGE). Compared with patients with low amyloid burden loads (ECV group I), those at moderate and high (ECV group II and III) show progressive impairment in LA reservoir, conduit, and booster strains and strain rates. A total of 44 patients died during a median follow-up of 12 months. In multivariate analysis, LA reservoir strain, New York Heart Association (NYHA), and ECV remained independently associated with survival. On Kaplan-Meier analyses, low LA reservoir strain (< 8.6%) increased the risk of mortality. In moderate amyloid burden loads patients, low LA reservoir strain provides additive prognosis value. Progress left atrial remodeling and dysfunction are common findings in AL cardiac amyloidosis. The CMR-FT-derived LA reservoir strain provides independent and additive prognostic value for all-cause mortality in patients with AL cardiac amyloidosis.