Transthyretin amyloid cardiomyopathy in France: A cross-sectional multi-centre study (333 patients)

Aims

We designed a two-part epidemiological study, an observatory for amyloid transthyretin amyloidosis (OBSAMYL). The first objective was to identify and count the number of patients diagnosed with ATTR amyloidosis in participating French centres. The second was to evaluate the use and safety profile of tafamidis meglumine in real-world settings.

Methods

This was a non-interventional descriptive retrospective multi-centre national study. A census was conducted to estimate the number of patients diagnosed with ATTR amyloidosis who were still alive at the time of the study (defined as 1 June 2017). Patients with ATTR amyloidosis were contacted by French centres from the French Rare Diseases network program. Patients aged ≥18 years with hereditary transthyretin-mediated amyloidosis (ATTRv) or wild-type transthyretin amyloidosis (ATTRwt) or a pathogenic transthyretin (TTR) mutation were eligible.

Results

Of the 38 centres (13 cardiology and 25 neurology) invited to participate, 22 (60.5%) (10 cardiology, 12 neurology) participated. There were 333 patients in cardiology census population. Before diagnosis one-fourth of the patients had cardiac decompensation, and one-fifth had a pacemaker. The 177 ATTRwt-CM patients were older (80.1 ± 7.0 years versus 64.2 ± 14.3 years; P < 0.001), had a higher incidence of hypertension (51.4% versus 35.3%; P = 0.003), and a higher incidence of arrhythmia (45.8% versus 28.3%; P = 0.001) than 156 ATTRv patients. There were no differences in disease severity according to New York Heart Association classification. The ATTRv-mixed + CM group had more neurological symptoms (paraesthesia or dysesthesia, neuropathic pain, digestive disorders, and orthostatic hypotension) than the ATTRwt-CM group (P < 0.001). Biopsies were performed on nearly 90% of patients with most of them being positive. The most common biopsy sites were salivary glands (137 biopsies) and cardiac tissues (77 biopsies). Tafamidis meglumine was administered to 174 cardiology patients, including 96 with ATTRv-mixed, 61 with ATTRwt-CM, and 17 with ATTRv-CM. Tafamidis meglumine was generally well tolerated. 18 adverse events, including 12 severe adverse events were reported in 174 patients as safety-related incidents. Tafamidis meglumine was likely responsible for five adverse events, one of which was severe.

Conclusion

This study of real-world clinical ATTR amyloidosis cases in France further elucidated the characteristics of and diagnostic approach to a cardiology patient population census of 333 patients. As of June 1, 2017, 177 ATTRwt-CM, 117 ATTRv-mixed, and 39 ATTRv-CM patients were alive. Our experience with tafamidis meglumine in the cardiology population confirmed its good tolerance.