Prevalence and Predictors of Transthyretin Amyloidosis in Patients Who Underwent Transcatheter Aortic Valve Implantation

Transthyretin amyloidosis (ATTR) is present in patients with aortic stenosis and has been reported recently in several studies.1 Transthyretin cardiac amyloidosis (ATTR-CA) is a complex and underdiagnosed cause of heart failure. Recent advances in cardiac imaging enabling noninvasive diagnosis of ATTR-CA have precipitated an increase in identification of the disease. In patients with aortic stenosis, ATTR-CA has more frequently been identified. As aortic valve intervention becomes more common due to the aging population, it is highly clinically relevant to identify patients with ATTR-CA, to ensure appropriate therapeutic interventions are taken from both the diagnostic and treatment standpoints. Balciunaite and colleagues recently published a thorough synopsis of studies investigating the relationship between these 2 comorbid conditions.2 In their review, they concluded that, in the context of aortic stenosis, the detection of cardiac amyloid deposits may be particularly difficult due to overlapping aspects from both clinical and imaging perspectives. However, they noted that the occurrence of ATTR-CA is correlated with a more severe phenotype of aortic stenosis, (low-flow low-gradient aortic stenosis), and early data suggest that to date, this is associated with worse outcomes, regardless of therapeutic approaches. Therefore, it is important to investigate the relationship between these overlapping conditions, with the intention of elucidating optimal treatment approaches.

Yuki Muto, MD, of the Fukushima Medical University in Fukushima, Japan, and colleagues surveyed aortic stenosis patients undergoing transcatheter aortic valve implantation (TAVI) to understand the prevalence of ATTR and compare clinical characteristics between aortic stenosis patients with and without ATTR. The intent of this study was to detect predictors of ATTR amyloidosis in the aortic stenosis patient population.

The researchers analyzed 32 patients with severe aortic stenosis who were screened for ATTR prior to TAVI. In 24 patients, they performed cardiac technetium-99m pyrophosphate (Tc-PYP) scintigraphy and in 24 patients they performed biopsies of fat tissue from the puncture site.

Of the 32 aortic stenosis patients who were screened for ATTR, 18.8% (6) were diagnosed with the disease by fat biopsy (N = 5) and cardiac Tc-PYP scintigraphy (N = 2). Compared with non-ATTR patients, ATTR patients had greater levels of B-type natriuretic peptide (BNP; 242.3 vs 1101.4 ng/mL; P = .004), smaller left ventricular ejection fraction (LVEF; 62.3% vs 45.5%; P = .002), and smaller mean pressure gradient of aortic stenosis (50.2 vs 32.0 mm Hg; P = .016).

Age, sex, clinical frailty scale, Society of Thoracic Surgeons score, prevalence of chronic kidney disease and atrial fibrillation, as well as levels of albumin, estimated glomerular filtration rate, hemoglobin, and troponin I were similar between the 2 groups. There was also very little difference between the 2 groups with respect to echocardiographic factors such as posterior wall thickness, interventricular septal wall thickness, and aortic valve area. Analysis revealed that the area under the curve of BNP, LVEF, and mean pressure gradient was 0.814, 0.766, and 0.846, respectively; this was used to identify ATTR among aortic stenosis patients. TAVI was successfully completed in all patients, and there were no complications reported in association with procedures in either group. However, 1 patient was rehospitalized due to decompensated heart failure 3 weeks after TAVI.

Muto and colleagues concluded that screening of ATTR should be considered in aortic stenosis patients undergoing TAVI, particularly in cases of low-flow low-gradient pattern and high BNP levels. In this population, fat biopsy and cardiac Tc-PYP scintigraphy are useful tools for detecting latent ATTR.

References

  1. Muto Y, Yoshihisa A, Oikawa M, et al. Prevalence and predictor of transthyretin amyloidosis in patients who underwent transcatheter aortic valve implantation. Presented at: American Heart Association Scientific Sessions 2020; November 13-20, 2020. Abstract P1855-2020.
  2. Balciunaite G, Rimkus A, Zurauskas E, et al. Transthyretin cardiac amyloidosis in aortic stenosis: prevalence, diagnostic challenges, and clinical implications. Hellenic J Cardiol. 2020;61:92-98.
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