PMC8588756_01
(A) Electrocardiography at presentation showed atrial fibrillation with rapid ventricular response but no evidence of low QRS voltage. (B) Echocardiography showed severe global hypokinesis of the left ventricle with a concentric wall thickness.
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F1
AF with rapid ventricular response and voltage criteria for left ventricular hypertrophy as per Cornell criteria (Figure 1A). Although his chest pain resolved, cardiac enzymes revealed acute myocardial injury (troponin I increased from 10 ng/mL to > 40 ng/mL, normal limit < 0.4 ng/mL). Electrocardiography showed globally reduced biventricular systolic function with concentric left ventricular (LV) wall thickness of 17 mm (Figure 1B).
Cardiovascular magnetic resonance imaging showed (A, B) diffusely increased left ventricular wall thickness with (C-E) diffuse patchy late gadolinium enhancement (LGE) in the left ventricle and both atria consistent with cardiac amyloidosis. (D, E, arrow) There also is dense focal transmural LGE in the basal anterior and anterolateral wall with microvascular obstruction at its center and myocardial edema noted on T2 mapping images (F, arrow) that suggest acute myocardial infarction in a ramus or diagonal artery distribution. Image enlarged using letsenhance.io.
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Cardiovascular magnetic resonance (CMR) imaging confirmed diffusely increased LV wall thickness (maximum thickness 20 mm; Figure 2A, B), severely reduced biventricular systolic function, and diffuse patchy late gadolinium enhancement (LGE) in the left ventricle and both atria consistent with cardiac amyloidosis (CA) (Figure 2C, E). Interestingly, CMR also showed dense, focal, transmural LGE in the basal anterior and anterolateral wall (Figure 2D, E) with evidence of localized myocardial edema on T2 mapping images (Figure 2F) and microvascular obstruction (Figures 2D, E and 3A-E), which suggested acute myocardial infarction in the ramus or diagonal branch artery.
Cardiovascular magnetic resonance imaging with inversion recovery sequence using long inversion time showed area of no contrast uptake at the basal anterior and anterolateral wall (A, B, E, blue arrows) that improved on the similar sequence repeated 30 minutes later (C, D, arrows) consistent with microvascular obstruction. (E, F) Left atrial appendage thrombus (yellow arrow) was also discovered on this sequence. Image enlarged using letsenhance.io.
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F3
Interestingly, CMR also showed dense, focal, transmural LGE in the basal anterior and anterolateral wall (Figure 2D, E) with evidence of localized myocardial edema on T2 mapping images (Figure 2F) and microvascular obstruction (Figures 2D, E and 3A-E), which suggested acute myocardial infarction in the ramus or diagonal branch artery. Additionally, a 1.1-cm thrombus was visualized in the left atrial appendage (LAA) on inversion recovery images using a long inversion time (Figure 3E-F). Endomyocardial biopsy confirmed transthyretin CA (ATTR-CA; Figure 3F), and genetic testing uncovered a Val122Ile mutation.
(A-C) Coronary angiography showed patent coronary arteries. (D, E) 99mTechnetium pyrophosphate imaging demonstrated significant (grade 2) myocardial uptake. (F) Endomyocardial histology with Congo red stain under polarized light showed the characteristic "apple green birefringence" that confirmed diagnosis of cardiac amyloidosis.
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Repeat coronary angiography confirmed patent coronary arteries (Figure 4A-C). Serum and urine immunofixation excluded monoclonal gammopathy; however, the serum kappa/lambda free light chain ratio was borderline abnormal. 99mTechnetium pyrophosphate imaging showed significant (grade 2) myocardial uptake (Figure 4D-E).