Clinical red flags associated with transthyretin amyloid cardiomyopathy in patients with left ventricular hypertrophy: results of the TTRACK study

Abstract

Abstract Background Transthyretin amyloid cardiomyopathy (ATTR-CM) is a life-threatening, systemic disorder that results in progressive physical disability, substantially reduced quality of life, and high morbidity and mortality rates. ATTR-CM is an underrecognized cause of increased left ventricular (LV) wall thickness in older adults, and delayed diagnosis can lead to worse clinical outcomes. To facilitate early identification of patients with LV hypertrophy (LVH) at risk for ATTR-CM, greater recognition of diagnostic ‘red flags’ is required. Purpose To determine the association between diagnostic red flags and ATTR-CM in patients with LVH. Methods TTRACK is a multicentre, non-interventional epidemiological study (ClinicalTrials.gov: NCT03842163). Eligible patients were ≥50 years of age and had unexplained LVH (LV maximum wall thickness ≥15 mm [echocardiogram]). After undergoing technetium-99m-DPD/-PYP/-HMDP-labelled bone scintigraphy, scans were categorized by the degree of tracer uptake in the heart; Perugini grades 0, 1, 2 and 3 represented absent, low, moderate and high uptake, respectively. Immunofixation electrophoresis was used to detect monoclonal protein abnormalities; grade 2 and 3 scans without evidence of monoclonal gammopathy were considered diagnostic for ATTR-CM. The frequency of predetermined clinical disease markers was compared in patients without monoclonal protein abnormalities and grade 0 or grade 2/3 scans. Results Of 766 eligible patients with scintigraphy data, 521 (68.0%) had grade 0 cardiac uptake; 37 (4.8%) had grade 1; and 208 (27.2%) had grade 2/3. Among patients with moderate/high uptake, 137 (65.9% of those with grade 2/3 uptake; 17.9% of the overall cohort) had no monoclonal protein abnormalities (ATTR-CM); 56 (26.9%) had monoclonal gammopathy of undetermined significance or light chain amyloidosis; and 15 (7.2%) patients had unknown monoclonal test findings. On univariable analysis, carpal tunnel syndrome (odds ratio [95% CI], 27.7 [16.7, 46.1]), permanent atrial fibrillation (3.4 [2.2, 5.2]), male sex (2.9 [1.8, 4.8]) and advanced heart failure (1.8 [1.2, 2.9]) were the strongest predictors for grade 2/3 scans; on multivariable analysis, carpal tunnel syndrome (50.3 [23.4, 108.0]), male sex (9.1 [3.9, 21.3] and age (1.7 [1.4, 2.1]) were the strongest predictors (Figure). Conclusions In the TTRACK study, 18% of patients ≥50 years of age with unexplained LVH ≥15 mm had ATTR-CM. Carpal tunnel syndrome, male sex and advanced age were associated with a greater likelihood of ATTR-CM.