Regional amyloid distribution and impact on mortality in light-chain amyloidosis: a T1 mapping cardiac magnetic resonance study

BACKGROUND: T1 mapping allows quantitative assessment of "diffuse" deposition of amyloid protein in the myocardium. Early detection of cardiac involvement and potential prognostic improvement could benefit patients with AL amyloidosis. OBJECTIVES: This study aims to evaluate the regional variation of amyloid infiltration in the left ventricle and the prognostic value of T1 mapping in patients with AL amyloidosis. METHODS: We prospectively enrolled 77 patients with AL amyloidosis who underwent cardiac magnetic resonance on a 3.0-T scanner. Native T1 and extracellular volume (ECV) were quantitated on the basal, mid, and apical levels of the left ventricle. Late gadolinium enhancement (LGE) pattern (no or non-specific LGE, sub-endocardial LGE, and transmural LGE) was also assessed. Forty healthy subjects served as controls. The primary end point was all-cause mortality. RESULTS: Basal ECV (26.9 ± 2.8% versus 31.1 ± 4.9%, p < .001) were lower than apical ECV in the healthy controls; however, basal ECV (60.6 ± 11.5% versus 53.0 ± 9.6%, p = .003) were significantly higher than apical ECV in patients with transmural LGE. During the follow-up period (median duration, 28 months; 25th-75th percentile, 13.5-38.0 months), 46 patients died. Basal ECV has the largest area under the curve of 0.845 (95% CI, 0.747-0.917) to predict all-cause mortality. Multivariable Cox analysis indicated that basal ECV was an independent prognostic factor and showed incremental prognostic value beyond NYHA class, Mayo stage, and LGE pattern. CONCLUSION: We demonstrated that T1 mapping may have the potential to detect a characteristic amyloid deposition with a decreasing gradient from base to apex. Furthermore, myocardial ECV indicated that basal amyloid infiltration provided robust and incremental prognostic value in patients with AL amyloidosis.