Myocardial work in light-chain and transthyretin-related amyloidosis with preserved ejection fraction: a cardiovascular magnetic resonance study

Abstract Objectives To investigate pressure–volume loop (PV-loop) changes by cardiovascular magnetic resonance (CMR) imaging in cardiac amyloidosis (CA) patients with preserved left ventricular ejection fraction (LVEF), and to assess PV-loop parameters’ potential as subtype differential diagnostic markers. Materials and methods Between May 2017 and September 2023, 100 consecutive confirmed CA patients (14 transthyretin-related [ATTR-CA] and 86 light-chain [AL-CA]) and 40 age- and sex-matched healthy controls (HCs) were prospectively enrolled. PV-loop parameters were derived from CMR cine images and brachial blood pressure. Clinical and CMR parameters were compared between CA patients and HCs, as well as between CA subtypes. The correlations between PV-loop parameters and clinical and imaging parameters were assessed. Furthermore, the differential diagnostic performance of these PV-loop parameters was evaluated using the area under the receiver operating characteristic curve (ROC-AUC). Bootstrapping was performed 2000 times for internal validation. Results Compared to HCs, CA patients showed significantly lower stroke work index, potential energy index (PEI), and work efficiency (all p < 0.001). AL-CA patients had higher N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels (2358.00 [IQR: 903.25, 5559.00] vs 810.00 [IQR: 269.00, 1136.01] pg/mL, p = 0.002) and lower PEI (0.13 [IQR: 0.07, 0.15] vs 0.15 [IQR: 0.13, 0.19] J/m², p = 0.025) than ATTR-CA patients. NT-proBNP (β = −1.94, OR = 0.14, 95% CI: 0.03–0.64, p = 0.016) and PEI (β = 0.20, OR = 1.23, 95% CI: 1.07–1.44, p = 0.007) were independent predictors for AL-CA vs ATTR-CA differentiation, and combining these two parameters enhanced the diagnostic performance (bootstrapping AUC 0.847). Conclusion By providing pathophysiological insights into the distinctions between AL-CA and ATTR-CA, PV-loop parameters have the potential to serve as a complementary, contrast-free approach for differential diagnosis. Key Points Question PV-loop changes by CMR in CA patients with preserved LVEF remain unknown. Findings Light-chain CA patients with preserved LVEF had higher NT-proBNP levels and lower PEI than transthyretin-related CA patients. Critical relevance statement The CMR-derived PV-loop parameters revealed pathophysiological differences between the two subtypes of CA, suggesting potential differential diagnostic value.