Ruling in or out the presence of cardiac amyloidosis based on cut-off values using T1-mapping – caution is required regarding the control group. (25th November 2020)

• Record Type: Journal Article
• Authors: Korthals, D; Chatzantonis, G; Bietenbeck, M; Meier, C; Florian, A; Yilmaz, A
• Is Part Of: European heart journal. Volume 41:(2020)Supplement 2
• Publication Date: 2020-11-25
• Subjects: Infiltrative Myocardial Disease; Cardiology -- Periodicals; Heart -- Diseases -- Periodicals; 616.12005
• DOI: 10.1093/ehjci/ehaa946.2119
• Languages: English
• ISSNs: 0195-668X

Abstract

Abstract: Background: Cardiac amyloidosis (CA) is an infiltrative disease that is characterized by accumulation of amyloid deposits in the interstitium of the myocardium. In contrast, hypertrophic cardiomyopathy (HCM) is caused by a disorganized arrangement of myocyte hypertrophy as well as expanded extracellular matrix, composed of interstitial and replacement fibrosis. Purpose: A diagnostic algorithm based on (native) T1-mapping using cardiovascular magnetic resonance (CMR) was suggested in a recent study for the diagnosis of CA: A native T1 <1, 036ms was mentioned to have a 98% negative predictive value (NPV) for ruling out CA whereas a native T1 >1, 164ms showed a 98% positive predictive value (PPV) for the presence of CA. In the present study, we critically addressed the calculation of such cut-off values considering possible differences in the composition of the control group. Methods: N=30 patients with CA, N=20 patients with HCM and N=15 healthy controls without relevant cardiac disease underwent dedicated CMR studies on a 1.5-T MR scanner. The CMR protocol comprised standard sequences for cine-imaging, native and post-contrast MOLLI-based T1-mapping and late-gadolinium-enhancement (LGE). ECV measurements were based on pre- and post-contrast T1-mapping images. Results: Native T1 and ECV were significantly increased in CA compared to HCM and receiver operating characteristic (ROC) analyses revealed an area-under-the-curve (AUC) = 0.984 for native T1 (p<0.001) and AUC = 0.985 for ECV (p<0.001) regarding the diagnosis of CA). When CA patients were compared to HCM patients (excluding healthy controls), a native T1 <1, 036ms or an ECV <33% were associated with a 99% NPV for ruling out CA whereas a native T1 ≥1, 082ms or an ECV ≥41% were associated with a 99% PPV for diagnosis of CA. However, when CA patients were compared to healthy controls (excluding HCM patients), a native T1 <1, 025ms or an ECV <34% were associated with a 99% NPV for ruling out CA whereas a native T1 ≥1, 025ms or an ECV ≥34% were associated with a 99% PPV for diagnosis of CA since there was no overlap in native T1 and ECV values between CA patients and healthy controls. Conclusion: Cut-off values for native T1 or ECV derived from ROC analyses (in a specific group of study patients) for ruling in or out the presence of CA are – amongst others - determined by the native T1 and ECV values of the respective "control group". A different composition of the control group (e.g. HCM patients vs. healthy volunteers) will result in different cut-off values. Hence, previously suggested cut-off values obtained in single center studies need to be considered carefully – with a special attention to the control group of the underlying study – and should not be transferred to other centers carelessly. Funding Acknowledgement: Type of funding source: None