A rare presentation of cardiac amyloid deposits isolated to intramural vessels.

The present case illustrates the diagnostic challenges in symptomatic patients with heart failure of unknown etiology. The patients were previously diagnosed with κ-light chain amyloidosis without cardiac involvement. Echocardiography showed heart failure with mildly reduced ejection fraction but no signs of amyloidosis. Coronary angiogram showed normal arteries and 11C-PIB positron emission tomography was negative for amyloid deposits. Exercise testing revealed severe heart failure and reduced coronary flow velocity reserve. Endomyocardial biopsies showed amyloid in the intramural coronary arteries without interstitial amyloid deposits. Hence, the patient was diagnosed with microvascular dysfunction-induced heart failure due to vessel wall amyloidosis.