Regional myocardial microvascular dysfunction in cardiac amyloid light-chain amyloidosis: assessment with 3T cardiovascular magnetic resonance

Coronary microvascular dysfunction is highly prevalent in patients with amyloid light-chain (AL) cardiac amyloidosis (AL-CA). The aim of this study was to clarify the feasibility of first-pass perfusion imaging using 3 T cardiovascular magnetic resonance (CMR) for evaluating the difference in left ventricular (LV) regional myocardial microvascular function among normal subjects and in patients with AL-CA. The amyloidosis patients were classified into those with impaired systolic function [LV ejection fraction (LVEF) < 50 %] and those with preserved systolic function.

In total, 32 patients with biopsy-proven AL-CA, including 11 AL-CA patients with systolic dysfunction, 21 AL-CA patients with preserved systolic function, and 25 healthy subjects, underwent CMR examination. LV regional myocardial perfusion parameters included upslope, time to maximum signal intensity (TTM) and max signal intensity (MaxSI) were compared among the three patient groups. Receiver operating characteristic analysis was performed to determine whether perfusion parameters could be used in discriminating regional myocardial microvascularity between AL-CA patients and normal subjects.

The patients with AL-CA had significantly reduced first-pass perfusion upslope and MaxSI, and increased TTM compared with the normal subjects (all P < 0.01). Compared with the patients with AL-CA and preserved LVEF, the patients with AL-CA and impaired systolic function had a longer TTM in the basal (47.05 ± 16.59 vs. 39.68 ± 19.11; P = 0.002) and mid-ventricular (44.61 ± 16.34 vs. 37.74 ± 18.25; P = 0.002) segments; lower upslope in the basal (2.41 ± 1.32 vs. 3.60 ± 1.68; P < 0.0001), mid-ventricular (2.82 ± 1.34 vs. 4.15 ± 2.02; P < 0.0001), and apical (3.71 ± 1.38 vs. 4.97 ± 2.55; P = 0.004) segments; and lower MaxSI (31.67 ± 15.23 vs. 37.96 ± 11.15; P < 0.0001) in the basal segment. The ROC curve analysis revealed that the first-pass upslope, TTM, and MaxSI may be used as indicators for differentiating microcirculation between AL-CA patients with preserved or impaired systolic function and normal subjects.

The differences in LV regional myocardial microvascular function among normal subjects, AL-CA patients with systolic dysfunction, and AL-CA patients with preserved systolic function can be monitored using first-pass perfusion CMR.