Hereditary and wild type transthyretin amyloid cardiomyopathy in Bulgaria in patients suspected for cardiac amyloidosis

Introduction: Transthyretin amyloid cardiomyopathy (ATTR-CM) is a severe progressive disease, more common than previously expected. The main objectives were to evaluate hereditary and wild type ATTR-CM frequency and clinical manifestations. Material and methods: One hundred seventy-eight patients at mean age 68 ± 13 years (129 males), referred by cardiologists with suspected cardiac amyloidosis (left ventricular wall thickness ≥ 12 mm and red flags) were evaluated. Pyrophosphate scintigraphy (99mTc-PYP) grade 2-3 myocardial uptake in the absence of monoclonal protein confirmed the diagnosis. Genetic test differentiated variant from wild type ATTR-CM. Endomyocardial biopsy with amyloid typing was performed in two patients. Results: Cardiac amyloidosis was diagnosed in 69 patients: light chain in 24 (13%) and ATTR-CM in 45 patients (25%). Wild type (ATTRwt) was found in 21 (12%) male patients at mean age 81 ± 6 years and variant type (ATTRv) in 24 patients (13%) at mean age 58 ± 7 years (15 males). In all ATTRv-CM patients some degree of peripheral polyneuropathy was found. The most common clinical red flags at diagnosis in both ATTRv and ATTRwt were heart failure in all patients, atrial fibrillation (16; 36%), pacemaker (5; 11%), and carpal tunnel syndrome (8; 18%). Severe aortic stenosis (4; 19%), spinal stenosis (2;10%), biceps tendon rupture (1; 5%) were characteristic for the wild type. At follow up, four patients needed a pacemaker for high degree AV block, six patients developed new onset atrial fibrillation, seventeen patients needed either initiation or an increase of the dose of loop diuretic, another 7 patients were hospitalized for heart failure exacerbation. Eight patients (18%) died, 7 (33%) with ATTRwt-CM and 1 (4%) with ATTRv-CM, all with advanced heart failure, 4 with concomitant severe aortic stenosis. Conclusions: This study provides the first nationwide estimates of the frequency and the clinical manifestations of ATTR-CM. Confirming the severity of the disease and poor prognosis, a low threshold for screening is needed for early diagnosis and timely treatment.