Tracing the Journey Among Patients with Tc-Pyrophosphate–Positive Transthyretin Cardiac Amyloidosis

As a condition that is often unrecognized and therefore underdiagnosed, transthyretin cardiac amyloidosis (ATTR-CA) is more prevalent than previously thought.

As part of a phase 1 clinical phenotyping study, Andrew Abboud, MD, of Harvard Medical School, and colleagues identified a random sample of 46 patients with a grade 2 or 3 positive 99mtechnetium(Tc)-pyrophosphate (PYP) scan without light chain amyloidosis. Patient demographics, International Classification of Diseases (ICD) codes, clinical notes, laboratory data, and clinical encounters were identified from electronic health record data.

From the phase 1 cohort, baseline characteristics will be used to detect clinically relevant variables to be tested in a larger phase 2 phenotyping study. Included in the study were 41 male patients who constituted 89.1% of the overall study population. The median patient age was 77 years, and most (80.4%) patients were white.

Other studies have noted that total hip and knee arthroplasties are much more common in patients with ATTR-CA compared with the general population, and that arthroplasty often occurs significantly before an ATTR-CA diagnosis is made.1 In this study population, arthroplasty occurred at a rate of 19.6%.

Anemia, chronic kidney disease, coronary artery disease, and hyperlipidemia were diagnosed via ICD code in 28.3%, 30.4%, 37.0%, and 50% of participants, respectively. Nearly 1 in 5 (19.6%) of these patients had received a cardiac pacemaker. The overall prevalence of heart failure with preserved ejection fraction was 65.2%, prior to a positive PYP scan, with a median of 10.5 encounters before a positive PYP scan.

The researchers reported that of these patients, 97.6% had left ventricular hypertrophy or thickening on transthoracic echocardiography inspection, and nearly half (47.8%) had atrial fibrillation. In addition, more than one-fifth (21.7%) of these patients had spinal stenosis, and carpal tunnel syndrome was diagnosed in 10.9% of patients.

Circulating biomarkers prior to diagnosis were tracked and charted retrospectively with N-terminal-pro hormone B-type natriuretic peptide levels increasing from 1913 ng/L at visit –3 to 3108.0 ng/L at visit –2 to 3624.5 ng/L at visit –1. Similarly, high-sensitivity troponin T-levels increased from 46.0 ng/L at visit –3 to 50.5 ng/L at visit –2 and finally to 65.0 ng/L at visit –1.

The authors concluded that based on the heterogeneity of the clinical presentation of ATTR-CM, it often remains undiagnosed until the later stages of the disease.

Source: Abboud A, et al. Care trajectory and early clinical features among patients with 99mTc-pyrophosphate positive transthyretin amyloid cardiomyopathy (ATTR-CM). Presented at: American College of Cardiology 69th Annual Scientific Session & Expo. March 20-30, 2020. Poster 155.


  1. Rubin J, Alvarez J, Teruya S, et al. Hip and knee arthroplasty are common among patients with transthyretin cardiac amyloidosis, occurring years before cardiac amyloid diagnosis: can we identify affected patients earlier? Amyloid. 2017;24:226-230.

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