Imaging for prevalence assessment of cardiac transthyretin amyloidosis in patients > 60 years hospitalized in cardiology : the IMPACT study

Abstract

Abstract Introduction Transthyretin cardiac amyloidosis (ATTR-CA) is a severe condition with poor prognosis if left untreated (1). Its true prevalence remains unknown because of frequent underdiagnosis, and most published series have focused on highly selected populations (2-3). The objectives of this prospective study were 1) to determine the prevalence of ATTR-CA in consecutive patients > 60 years hospitalized in cardiology wards and presenting with left ventricular hypertrophy (LVH) ≥ 12 mm on transthoracic echocardiography (TTE), using a systematic 99mTc-HMDP bone scintigraphy for diagnosis screening 2) to analyze the characteristics associated with the final diagnosis of ATTR-CA. Population & methods: Between october 2021 and june 2022, 251 patients with echocardiographic LVH (from any cause, including high blood pressure or aortic stenosis) and without any previous diagnosis of CA, were prospectively included and underwent 99mTc-HMDP bone scintigraphy. A monoclonal gammapathy was systematically sought-after to exclude light-chain cardiac amyloidosis (AL-CA) (4). Genetic analysis of the TTR gene was systematically performed in case of definite diagnosis of ATTR-CA. The design of the trial is provided in Figure 1. This is an interim analysis of a private funded study currently being finalized, with a target of 400 patients to be included. Results Among the 251 patients, definite ATTR-CA was diagnosed in 17 patients (6.8%), all of them being wild-type. No AL-CA was identified. The 2 subgroups of patients with the highest prevalence of ATTR-CA (>10%) were patients ≥ 65 years with either heart failure or bilateral carpal tunnel syndrom. The majority of diagnosed patients had symptoms or signs suggestive of ATTR-CA, even though CA was never looked-after during their medical pathway, while 30% had no or only one red flag of ATTR-CA. Using multivariable analysis, we found four parameters independently associated with the diagnosis of ATTR-CA as presented in Table 1, one clinical and three echocardiographic, including the alteration of left atrial strain. Conclusion We report a high prevalence (6.8%) of ATTRwt-CA in a non-selected cardiological population with LVH from any cause. Most patients were underdiagnosed since they had at least 2 red-flags for ATTR-CA, thus emphasizing the need for continuous and strengthened education on CA. On the other hand, 30% of patients had no obvious sign for CA and the diagnosis was only established by our systematic screening strategy. We report 4 factors significantly associated with ATTR-CA in our population, including the alteration of left atrial reservoir strain. These new data confirm the interest of a complete echocardiographic analysis in case of LVH, to refine the selection of patients who could benefit from 99mTc-HMDP bone scan screening.Study designPredictive factors of ATTR-CA