Assessment of ATTR Cardiac Amyloidosis in Patients with Left Ventricular Hypertrophy Using Tc-99m Pyrophosphate Scintigraphy.

Abstract

Introduction: Amyloidosis is characterized by the extracellular deposition of fibrillar proteins, leading to tissue damage and dysfunction. Cardiac amyloidosis (CA) occurs when these fibrils accumulate in the heart's extracellular matrix, causing infiltrative cardiomyopathy, heart failure, and potentially death. Early diagnosis is imperative in accurate management. Transthyretin amyloidosis, either hereditary or age-related, is a common cause of CA, often presenting with left ventricular hypertrophy (LVH) and heart failure with preserved ejection fraction (HFpEF). This study investigates the utility of Tc-99 m Pyrophosphate (Tc-99 m PYP) imaging in diagnosing Transthyretin Amyloidosis ((ATTR)-CA) in patients with unexplained LVH.

Materials and methods: This prospective observational study, conducted between January 2023 and June 2024, involved 52 patients with clinical suspicion of CA and left ventricular wall thickness >12 mm. Patients underwent Tc-99 m PYP scintigraphy, and the results were categorized as positive, negative, or equivocal.

Results: The study population's mean age was 64.6 years, with a male predominance (69%). Of the 52 patients, 9 (17.3%) had positive, 28 (53.8%) negative, and 15 (28.8%) equivocal Tc-99 m PYP scan results. Echocardiographic features, such as septal hypertrophy and granular speckled appearance, were significantly associated with positive scan findings. Comorbidities such as coronary artery disease and dyslipidemia were also common. Cardiac biomarkers NT-proBNP and troponin I showed elevated levels in patients with positive scan results.

Conclusion: Tc-99 m PYP imaging is an effective noninvasive tool for diagnosing ATTR CA, particularly in patients with unexplained LVH. The presence of HFpEF, abnormal ECG, and restrictive features on echocardiography should prompt further investigation for CA. Early diagnosis allows for timely management, improving patient outcomes.