Which imaging tests are best for distinguishing cardiac amyloidosis from other heart issues?

Cardiac amyloidosis (CA) is a condition where abnormal proteins build up in the heart muscle, causing it to thicken and stiffen. This can look like other heart problems, such as hypertrophic cardiomyopathy (HCM) or aortic stenosis. The right imaging tests can help tell them apart. Cardiac MRI (CMR) with contrast and bone scintigraphy are the most accurate tests, while echocardiography is often used first to raise suspicion.

What the research says

Echocardiography, especially with strain imaging, is often the first test that suggests CA. A pattern called 'apical sparing' (where the tip of the heart moves better than the base) is a key clue. A meta-analysis found that this pattern has moderate accuracy, with a sensitivity of about 66% and specificity of 83% for detecting CA ³. Another review reported similar results, with sensitivity 73% and specificity 77% ¹. However, this pattern can be less reliable in people with severe aortic stenosis ¹.

Cardiac MRI (CMR) provides more detailed tissue information. It can measure T1 relaxation time and extracellular volume (ECV), which are often elevated in CA. In patients with advanced kidney disease, a T1 time above 1390 ms had 75% sensitivity and 85% specificity for CA, while an ECV of 45% or higher had 75% sensitivity and 80% specificity ⁴. CMR also shows a distinct pattern of late gadolinium enhancement (LGE) — diffuse and subendocardial in CA, versus patchy mid-wall in HCM ⁵. A machine learning model using CMR data could distinguish CA from HCM and even tell apart the two main types of CA (AL and ATTR) ⁸.

Bone scintigraphy (a nuclear medicine scan) is highly accurate for detecting transthyretin (ATTR) cardiac amyloidosis, especially when combined with blood tests to rule out light chain (AL) amyloidosis ⁶. A machine learning tool called Amylo-Detect, which uses routine health data to guide bone scintigraphy referrals, showed excellent performance with an AUC of 0.91 in external validation ². Myocardial perfusion imaging (MPI), another nuclear test, can also detect the apical sparing pattern and may help identify CA in people with left ventricular hypertrophy ⁷.

What to ask your doctor

• Should I have an echocardiogram with strain imaging to check for an apical sparing pattern?
• Would a cardiac MRI with contrast help clarify whether my heart thickening is due to amyloidosis or another cause?
• Is bone scintigraphy appropriate to confirm or rule out transthyretin (ATTR) cardiac amyloidosis?
• Do I need blood tests for monoclonal proteins to help distinguish AL from ATTR amyloidosis?
• Given my kidney function, is it safe to receive contrast for cardiac MRI or bone scintigraphy?