Development and Initial Results from the Canadian Cardiac Amyloidosis Pyrophosphate Imaging Registry (CAPER)

Transthyretin cardiac amyloidosis (ATTR-CM) is an increasingly recognized cause of heart failure in older adults. Technetium-99m pyrophosphate (PYP) imaging has emerged as a highly effective tool for diagnosing ATTR-CM. We established a multicentre Canadian registry to provide a platform for research regarding the prevalence of ATTR-CM and accuracy of methods for screening or diagnosis.

We included patients undergoing [^99mTc]PYP imaging at 4 Canadian centres. Medical history, red flags for cardiac amyloidosis, and laboratory biomarkers were collected. Diagnosis of ATTR-CM was established using standardized criteria. Deidentified clinical data and [^99mTc]PYP image files were transferred to the core laboratories.

In total, 2,118 patients are included in the registry with median age 77 (interquartile range: 68-83) and 1452 (68.6%) male patients. ATTR-CM was present in 618 (29.2%) patients and light chain amyloidosis in 112 (5.3%) patients. The volume of [^99mTc]PYP scans increased from 18 in 2016 to 515 in 2022, with the proportion of patients with ATTR-CM ranging from 41% to 19% since 2017. The risk score proposed by Davies et al. had higher area under the receiver operating characteristic curves for ATTR-CM (0.792, 95% confidence interval [CI], 0.771-0.813) compared with the score proposed by Nitsche et al. (0.750; 95% CI, 0.727-0.774; P = 0.002).

We assembled a large cohort of patients undergoing [^99mTc]PYP imaging at 4 Canadian centres, with detailed clinical and imaging data. This registry, which continues to grow over time, will serve as an important source for evidence regarding diagnosis and management of ATTR-CM.