Key Information
Cardiac amyloidosis is becoming increasingly recognized as an etiology for heart failure (HF). Most cases of amyloid cardiomyopathy will fall into one of two categories: light-chain amyloid (AL) amyloidosis resulting from misfolding of monoclonal immunoglobulin light chains or transthyretin amyloidosis with cardiomyopathy (ATTR-CM), due to misfolding of the transthyretin protein.1
The rise of newer imaging techniques over the last few years have allowed for accurate noninvasive diagnosis of ATTR-CM. This is incredibly important given the development of multiple therapeutic agents that can improve outcomes in these patients if they are diagnosed in an early stage of disease.
A Clinical Case
Imagine you're seeing Mr. M in clinic. He's a 75-year-old man who has had multiple recent hospitalizations for heart failure with preserved ejection fraction (HFpEF). He also has a history of atrial fibrillation (AFib) on apixaban and chronic kidney disease (CKD).
His blood pressure is 100/60 mm Hg with a pulse of 70 bpm. His medical history also includes bilateral carpal tunnel syndrome. A 12-lead echocardiogram shows AFib with slow ventricular response and a right bundle branch block. His recent echocardiogram confirms a normal EF with left ventricular hypertrophy (LVH).
Pathway to Diagnosis
Many patients will see multiple providers before receiving a diagnosis of cardiac amyloidosis. In one survey, less than 50% of patients received a diagnosis within six months of experiencing symptoms and some studies estimate that patients see more than five doctors before this diagnosis is reached.1-3
One may imagine that many older patients with HFpEF are comorbid with AFib and CKD. While this is true, it's important to keep one's eyes open for any red flags or clinical clues for cardiac amyloidosis. Some such clues are depicted in the Table. Our patient has evidence of conduction disease and has signs of LVH on his echocardiogram without systemic hypertension.
Cardiac Amyloidosis Suspected? What's Next?
Although cardiomyopathy due to AL amyloidosis is much rarer, it's essential that this be ruled out first, checking for monoclonal proteins, as the treatment pathway is significantly different and involves chemotherapeutic agents. This should include serum kappa/lambda free light chains as well as serum and urine immunofluorescence. If there's concern for a plasma cell disorder, hematology should be consulted for further diagnostic testing.