109. Nuclear and Multimodality Imaging: Cardiac Amyloidosis

CardioNerd Amit Goyal is joined by Dr. Erika Hutt (Cleveland Clinic general cardiology fellow), Dr. Aldo Schenone (Brigham and Women’s advanced cardiovascular imaging fellow), and Dr. Wael Jaber (Cleveland Clinic cardiovascular imaging staff and co-founder of Cardiac Imaging Agora) to discuss nuclear and complimentary multimodality cardiovascular imaging for the evaluation of multimodality imaging evaluation for cardiac amyloidosis. Show notes were created by Dr. Hussain Khalid (University of Florida general cardiology fellow and CardioNerds Academy fellow in House Thomas). To learn more about multimodality cardiovascular imaging, check out Cardiac Imaging Agora!

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Show Notes & Take Home Pearls - Nuclear and Multimodality Imaging: Cardiac Amyloidosis

Episode Abstract:

Previously thought to be a rare, terminal, and incurable condition in which only palliative therapies were available, multimodality imaging has improved our ability to diagnose cardiac amyloidosis earlier in its disease course. Coupled with advances in medical therapies this has greatly improved the prognosis and therapeutic options available to patients with cardiac amyloidosis. Multimodality imaging involving echocardiography with strain imaging, 99mTc-PYP Scan, and cardiac MRI can help diagnose cardiac amyloidosis earlier, monitor disease progression, and even potentially differentiate ATTR from AL cardiac amyloidosis.

Five Take Home Pearls

Cardiac amyloidosis results from the deposit of amyloid fibrils into the myocardial extracellular space. The precursor protein can either be from immunoglobulin light chain produced by clonal plasma cells (in the setting of plasma cell dyscrasias) or transthyretin (TTR) produced by the liver (which can be  “wild type” ATTR caused by the deposition of normal TTR or a mutant ATTR  which is hereditary). These represent AL Cardiac Amyloidosis and ATTR Cardiac Amyloidosis respectively.Remember that amyloidosis can affect all aspects of the heart:the coronaries, myocardium, valves, electrical system, and pericardium! Be suspicious in a patient with history of HTN who has unexpected decrease in the need for antihypertensive agents with age or presents with a lower-than-expected blood pressure.Multimodality imaging can assist with the diagnosis of cardiac amyloidosis in patients with a high clinical suspicion, monitor disease progression, and even potentially differentiate ATTR from AL cardiac amyloidosis.Strain imaging assessment of global longitudinal strain (GLS) in patients with amyloid may demonstrate relatively better longitudinal function in the apex compared to the base, termed “apical sparing” or “cherry on top” (though in advanced stages the base to apex strain difference tends to become smaller). This has a 93% sensitivity and 82% specificity in identifying patients with cardiac amyloidosis and is particularly helpful with differentiating true cardiac amyloidosis from “mimics” such as hypertrophic cardiomyopathy, aortic stenosis, or hypertensive heart disease.When the clinical suspicion for cardiac amyloidosis is high, a semiquantitative grade ≥ 2 (myocardial uptake ≥ bone) on 99mTc-PYP Scan combined with negative free light chain and immunofixation assays (to rule out AL cardiac amyloidosis) can diagnose ATTR cardiac amyloidosis and exclude AL cardiac amyloidosis w/ 100% PPV! Furthermore, this can circumvent the need for endomyocardial biopsy. Echocardiography and cardiac MRI (CMR) are helpful for building the clinical suspicion for cardiac amyloidosis.When there is suspicion for AL cardiac amyloidosis, tissue biopsy is mandatory.

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