Among patients with transthyretin amyloid cardiomyopathy (ATTR-CM), cardiovascular magnetic resonance (CMR) with extracellular volume mapping may track changes in cardiac amyloid burden and treatment response over time, according to a study published July 11 in EHJ.

Rishi K. Patel, MBBS, BSc, et al., looked at 189 patients diagnosed with ATTR-CM at the National Amyloidosis Centre (NAC), London, between June 2016 and June 2022 and assessed with CMR at baseline and follow-up; 119 patients were untreated, and 70 patients were treated with patisiran. Untreated patients were older (mean age, 74.2 vs. 64.1 years), more commonly men (90.8% vs. 70.0%), and had a more severe cardiac phenotype compared with patients treated with patisiran.

Results revealed that in the untreated population, 36% progressed after one year, with a significant increase to 62% after two years. The mean increase in extracellular volume was 4.1% after one year and 6.8% after two years. These increases were associated with progressive deterioration in functional and structural parameters.

For those treated with patisiran, no significant difference in mean extracellular volume was observed at either one (0.2% rise) or two (0.2% fall) years. Extracellular volume was stable (<5% change) in 88% of patients after one year and 100% after two years. After treatment, structural parameters and biomarkers also remained stable.

Notably, after adjusting for known predictors, extracellular volume progression (defined as ≥5% increase) after one year was independently associated with an increased risk of mortality (hazard ratio, 2.02; 95% CI, 1.08-3.78; p=0.028).

The authors write that the study findings should "support the adoption of a reduction in [extracellular volume] of ≥5% as the minimum threshold expected in patients treated with anti-ATTR amyloid therapies" and that the overall results highlight "the potential role of CMR with [extracellular volume] mapping in both clinical practice and clinical trials."