Suspected transthyretin cardiac amyloidosis by cardiac scintigraphy in heart failure with preserved ejection fraction, left ventricular hypertrophy and red flag manifestations

Abstract

Background Transthyretin Cardiac Amyloidosis (ATTR) is a type of restrictive cardiomyopathy, which typically manifests as Heart Failure with Preserved Ejection Fraction (HFpEF). The presence of unexplained left ventricular hypertrophy (LVH) associated with HF and red flag manifestations could increase the diagnostic probability. However, the diagnostic prevalence of this triad by cardiac scintigraphy remains uncertain. Methods From August 1st to December 31st, 2021, 22 consecutive patients diagnosed with a HF (ejection fraction more than 40%), LVH with unexplained etiology and at least one red flag clinical manifestation, underwent pyrophosphate scintigraphy (99mTc-PYP). The patients were divided into two groups: “Positive” and “Negative” (as defined by grade 2 or 3 uptake). Multiple logistic models were made with variable 99mTC-PYP and explanatory variables. Results Among 22 patients, 15 had a positive 99mTc-PYP study for ATTR. The prevalence of ATTR using the triad of HFpEF, unexplained LVH and at least one red flag was 68% (CI 95%; 45-86%). Patients with 99mTc-PYP positive tended to be male, older, and with an aortic mean gradient and interventricular septum higher, as compared to the group with a negative study. The most frequent red flag clinical manifestations were proteinuria (55%) and pseudoinfarction pattern (55%). The presence of 2 or more red flags could increase the diagnostic probability of the test (OR 1.6 (CI95% 0.52-4.89). Conclusions The diagnostic probability of ATTR by 99mTc-PYP scan could increased when a clinical manifestation of a red flag was added to the suspected diagnosis of heart failure and left ventricular hypertrophy. The use of non-invasive techniques allows early identification and treatment of this underdiagnosed disease.