Xiaohui Li ¹ Tongge Mu ² Yangxue Deng ³ Yu Zhang ¹ Yun Ti ¹ Lei Zhang ^1*

• ¹ Key Laboratory of Cardiovascular Remodeling and Function Research, Qilu Hospital, Shandong University, Jinan, Shandong Province, China
• ² Shandong University of Traditional Chinese Medicine, Jinan, Shandong Province, China
• ³ YanKuang New Journey General Hospital, Jining, China

Backgroud: Cardiac amyloidosis (CA) is a challenging diagnosis, particularly when the classic signs, such as increased wall thickness in a non-dilated left ventricle (LV), are absent. This makes the diagnosis more difficult in patients with normal LV wall thickness. We present a case of CA without increased wall thickness and without the characteristic granular sparking echotexture in a non-dilated LV.Case summary: A 50-year-old female presented with worsening breathlessness on exertion, paroxysmal nocturnal dyspnoea, oliguria and lower-extremity oedema.Electrocardiography showed low voltage in the limb leads and a pseudoinfact pattern in anterior leads. Echocardiographic evaluation revealed a non-dilated LV with normal wall thickness, no granular sparking echotexture of the myocardium, mildly dilated left atrium, restrictive filling (grade 3 diastolic dysfunction) and pericardial effusion. Two weeks later, a follow-up quantitive echocardiographic study showed a slight increase in LV wall thickness (still within the normal range), decreased global longitudinal strain (GLS), and a relative "apical sparing" pattern of longitudinal strain in the LV apex. After one month, LV wall thickness increased beyond the normal range, and the granular sparking echotexture became evident. Cardiac amyloidosis was subsequently confirmed by delayed gadolinium enhancement on cardiac magnetic resonance imaging, abnormal serum free light chains, positive serum immunofixation, and extracardiac biopsy positive for amyloid. Discussion: CA presented with normal wall thickness in the non-dilated LV might only be an early stage of CA. It can be easily overlooked and underappreciated. For smaller individuals, relative wall thickness (RWT) may be a more sensitive indicator for further investigation. In patients presenting with increased RWT, restrictive filling, and pericardial effusion in the absence of other plausible causes, CA should be considered, even in the absence of classical echocardiographic signs of amyloid deposition. Furthermore, two-dimensional speckle-tracking echocardiography can enhance clinical suspicion and should be recommended as part of the diagnostic workup.