Recognizing the Role That Technetium Pyrophosphate Uptake Plays in Identifying Cardiac Transthyretin Amyloidosis

Transthyretin amyloidosis (ATTR) remains underrecognized and underdiagnosed in the clinical setting. As recognition increases and noninvasive diagnostic techniques become more widespread, patients are being diagnosed earlier when treatment can be more beneficial.

Seo and colleagues investigated the positive testing rate for Tc-99m-pyrophosphate (Tc-99m-PYP) scintigraphy and patient demographics and factors that can predict positive Tc-99m-PYP scans. The investigators reviewed the medical charts of 120 patients who received a Tc-99m-PYP scan and a transthoracic echocardiogram (TTE) between July 2015 and February 2019 within the Lifespan healthcare system. Electrocardiograms (ECGs) administered up to 1 year prior to the patients’ Tc-99m-PYP tests were reviewed for the presence of atrial fibrillation. TTEs closest to the time of Tc-99m-PYP testing were evaluated to ascertain echocardiographic characteristics linked with a positive scan.

Nearly half (47.5%) of the patients had positive Tc-99m-PYP scans and were found to be significantly older on average than patients who received negative scans (80.8 years vs 74.3 years). The patients who received positive scans were also more likely to be male than those who had negative scans (84.2% vs 68.4). Positive Tc-99m-PYP test results were associated with a higher likelihood of low-voltage ECGs (44.4% vs 19.7%). Patients with positive scans were also more likely to have thicker left ventricular posterior walls (15.9 mm vs 12.9 mm) and a significantly thicker interventricular septum (16.1 mm vs 13.0 mm).

The investigators noted that the high percentage of positive Tc-99m-PYP results suggests that there may be patients with ATTR who are not being identified in the routine diagnostic process. In the future, they plan to analyze other possible contributing factors, including echocardiographic features such as apical-to-basal strain ratio and global longitudinal strain.

By characterizing specific aspects linked with positive Tc-99m-PYP scans, the investigators’ goal is to develop an analytical tool that can aggregate and predict, and thereby improve, diagnostic rates for ATTR detection.

Source: Seo A, Ali H, Garg H, et al. Characteristics of patients diagnosed with cardiac transthyretin amyloidosis by technetium pyrophosphate uptake within a healthcare system. Presented at: American College of Cardiology 2020 Scientific Session (ACC.20)/World Congress of Cardiology (WCC); March 28-30, 2020. Abstract 1308-075.

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