Prognostic value of left atrial function in systemic light-chain amyloidosis: A cardiac magnetic resonance study

Abstract

Background Cardiac involvement in systemic light-chain amyloidosis (AL) imparts an adverse impact on outcome. The left atrium (LA), by virtue of its anatomical location and muscular wall, is commonly affected by the amyloid process. Although LA infiltration by amyloid fibrils leads to a reduction in its pump function, the infiltration of the left ventricular (LV) myocardium results in diastolic dysfunction with subsequent increase in filling pressures and LA enlargement. Even though left atrial volume (LAV) is an independent prognostic marker in many cardiomyopathies, its value in amyloid heart disease remains to be determined. In addition, few data are available as to the prognostic value of LA function in systemic AL. Using cardiac magnetic resonance (CMR), the current study aims to assess the prognostic significance of the maximal LAV and total LA emptying fraction (LAEF) in patients with AL. Methods and results Fifty-four consecutive patients (age 66+10 years, 59% males) with confirmed systemic AL and mean LV ejection fraction of 60+12% underwent CMR. As compared with patients with no or minimal cardiac involvement (Mayo Clinic [MC] stage I), those at moderate and high risk (MC stages II and III) had significantly larger indexed maximal LAV (36+15 vs. 46+13 vs. 52+19 mL/m2, P 0.03) and indexed minimal LAV (20+6 vs. 34+11 vs. 44+17 mL/ m2, P , 0.001), lower LAEF (42+9 vs. 26+13 vs. 16+9%, P , 0.0001) but similar LVEF. Furthermore, myocardial late gadolinium enhancement (LGE) was more frequent and significantly associated with lower LAEF. LAEF was also significantly lower in symptomatic (NHYA II, 22+14%) as compared with asymptomatic patients (NYHA class I, 33+13%, P 0.006). Two-year survival rate was lower in patients with LAEF 16% as compared with those with LAEF . 16% (37+11 vs. 94+4%, P 0.001). In multivariate analysis, lower LAEF remained independently associated with a higher risk of 2-year mortality (HR 1.08 per 1% decrease, 95% CI: 1.02-1.15, P 0.003). Conclusion In patients with systemic AL, LAEF as assessed by CMR is associated with NYHA functional class, MC stage, myocardial LGE and 2-year mortality.