Pitfalls for the non-invasive diagnosis of wild-type transthyretin amyloid cardiomyopathy in a young adult: a case report

Hao-Chih Chang; Ling Kuo; Fa-Po Chung; Wen-Chung Yu

doi:10.1093/ehjcr/ytad308

Pitfalls for the non-invasive diagnosis of wild-type transthyretin amyloid cardiomyopathy in a young adult: a case report

Eur Heart J Case Rep. 2023 Jul 13;7(7):ytad308. doi: 10.1093/ehjcr/ytad308. eCollection 2023 Jul.

Authors

Hao-Chih Chang^{1

2

3

4}, Ling Kuo^{2

3

5

6}, Fa-Po Chung^{2

3

5

7}, Wen-Chung Yu^{2

3

5}

Affiliations

¹ Department of Medicine, Taipei Veterans General Hospital Taoyuan Branch, 100, Sec.3, Chenggong Road, Taoyuan District, Taoyuan 330023, Taiwan.
² Cardiovascular Research Center, National Yang Ming Chiao Tung University, 155, Sec. 2, Linong Street, Beitou District, Taipei 112304, Taiwan.
³ Department of Internal Medicine, College of Medicine, National Yang Ming Chiao Tung University, 201, Sec. 2, Shi-Pai Road, Beitou District, Taipei 112201, Taiwan.
⁴ Institute of Public Health, National Yang Ming Chiao Tung University, 155, Sec. 2, Linong Street, Beitou District, Taipei 112304, Taiwan.
⁵ Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, 201, Sec. 2, Shi-Pai Road, Beitou District, Taipei 112201, Taiwan.
⁶ Department of Biomedical Imaging and Radiological Sciences, National Yang Ming Chiao Tung University, 155, Sec. 2, Linong Street, Beitou District, Taipei 112304, Taiwan.
⁷ Institute of Clinical Medicine, National Yang Ming Chiao Tung University, 155, Sec. 2, Linong Street, Beitou District, Taipei 112304, Taiwan.

Abstract

Background: Using technetium (Tc)-labelled pyrophosphate (PYP) cardiac scintigraphy, a non-invasive diagnosis of transthyretin amyloid (ATTR) cardiomyopathy can be made without histopathological confirmation. In patients suspected of ATTR cardiomyopathy, however, atypical presentations may necessitate further investigation.

Case summary: A 30-year-old man with hypertension and end-stage renal disease on peritoneal dialysis presented with progressive exertional dyspnoea. Left ventricular hypertrophy (LVH) with a maximal end-diastolic wall thickness up to 16 mm was detected on echocardiography. Speckle-tracking analysis revealed a reduced longitudinal strain of left ventricle with a relative apical sparing pattern. Although the absence of monoclonal gammopathy, a grade 3 myocardial uptake in ^99mTc-PYP cardiac scintigraphy, and negative TTR gene mutation inferred the diagnosis of wild-type ATTR, the relative youth of the patient still raised concerns regarding the diagnosis. Under clinical doubt, he underwent further testing. In non-contrast cardiac magnetic resonance (CMR) with native T1 mapping, the native T1 myocardial value was within the normal range. In endomyocardial biopsy (EMB), there was no evidence of amyloid deposition, negative Congo red staining, and no immunohistochemical evidence of transthyretin expression. These results excluded the diagnosis of ATTR cardiomyopathy and prevented subsequent unnecessary treatments.

Discussion: When patients with unexplained LVH meet the non-invasive diagnostic criteria for ATTR cardiomyopathy, an EMB should be considered in selected cases. Patients presenting at an atypical age for wild-type ATTR cardiomyopathy, absence of extracardiac symptoms/signs or classic electrocardiogram features for cardiac amyloidosis should be suspected of another diagnosis and require further CMR or EMB to confirm.

Keywords: Case report; Endomyocardial biopsy; Technetium-labelled cardiac scintigraphy; Transthyretin amyloid cardiomyopathy.

Publication types

Case Reports