CMR imaging can now quantify myocardial amyloid burden and predict survival in ATTR. A study published in JACC: Cardiovascular Imaging defined reproducible ECV thresholds that improve both diagnostic accuracy and prognostic assessment in patients across the ATTR spectrum.

The analysis included 1,541 subjects, classified as transthyretin variant carriers (n=123), extra-cardiac ATTR (n=41), early-stage ATTR cardiomyopathy (n=70), and overt ATTR-CM (n=1,308). ECV rose progressively from early to overt disease. Diagnostic thresholds were robust: values below 30% excluded cardiac involvement, 30–39% indicated early infiltration, and levels ≥40% confirmed cardiac amyloid deposition.

Over a median follow-up of 2.8 years, 40% of participants died. Mortality risk increased with higher ECV categories and remained independent of conventional markers such as NT-proBNP, hs-troponin, Perugini grade, and left ventricular mass index. These findings establish CMR-derived ECV as a quantitative tool for staging and therapeutic planning in ATTR amyloidosis.