Altered Myocardial Oxygenation and Impaired Energy Efficiency: A Pilot Study in Patients With Light Chain Cardiac Amyloidosis.

BACKGROUND

Cardiac magnetic resonance (MR) enables assessment of myocardial oxygenation without contrast media. However, how myocardial oxygen metabolism is altered in light chain cardiac amyloidosis (AL-CA) patients remains poorly understood.

PURPOSE: To leverage newly developed MR techniques for the evaluation of altered myocardial oxygen metabolism in AL-CA patients.

STUDY TYPE: Prospective.

SUBJECTS: Twenty participants: 10 AL-CA patients (8 males) and 10 healthy controls (HCs; 8 males).

SEQUENCE: 3 T, cine imaging, T1 mapping, first-pass perfusion imaging, and asymmetric spin echo prepared (ASEprep) sequence.

ASSESSMENT: All subjects underwent cine imaging for left ventricular global longitudinal strain (LVGLS), pre- and post-contrast T1 mapping for extracellular volume (ECV), and ASEprep sequence for myocardial oxygen extraction fraction (mOEF) mapping. Myocardial blood flow (MBF) was derived from first-pass perfusion images, and myocardial oxygen consumption (MVO2) and myocardial external efficiency (MEE) were quantified.

STATISTICAL TESTS: T-test, U test, Firth penalized logistic regression, a one-way analysis of variance, and correlation analysis.

RESULTS

Compared with HCs, AL-CA patients demonstrated higher mOEF (0.66 ± 0.04 vs. 0.59 ± 0.02), native T1 (1395.4 ± 109.25 vs. 1236.97 ± 41.32), and ECV (40.39 ± 8.99 vs. 25.48 ± 2.03), but lower MBF (0.08[0.08, 0.12] vs. 0.13[0.11, 0.15]), MVO2 (0.06 ± 0.01 vs. 0.08 ± 0.01), and LVGLS (-13.34 ± 3.75 vs. -17.65 ± 1.78). MEE (63.2 ± 21.18 vs. 77.15 ± 19.68, p = 0.156) in AL-CA patients was reduced, whereas total MVO2 (6.25 ± 2.98 vs. 4.6 ± 1.27, p = 0.115) was increased, though not statistically significant. mOEF correlated strongly with LV mass (r = 0.72), moderately with ECV (r = 0.60), native T1 (r = 0.64), LVGLS (r = -0.52), and MBF (r = -0.65). MVO2 correlated moderately with ECV (r = -0.57), native T1 (r = -0.56), and LV mass (r = -0.60). MEE correlated strongly with LVEF (r = 0.78) and moderately with LVGLS (r = 0.59).

DATA

CONCLUSION

Our pilot cardiac MR study demonstrated the feasibility of quantifying myocardial oxygenation and mechanical efficiency in AL-CA. Elevated mOEF and reduced MBF suggest microvascular dysfunction from amyloid infiltration, while impaired MEE and increased total MVO2 underscore metabolic-mechanical uncoupling.

EVIDENCE LEVEL: 2.

TECHNICAL EFFICACY: Stage 1.