Background: Although impaired left ventricular (LV) global longitudinal strain (GLS) with apical sparing is a feature of cardiac amyloidosis (CA), its diagnostic accuracy has varied across studies. We aimed to determine the ability of apical sparing ratio (ASR) and most common echocardiographic parameters to differentiate patients with confirmed CA from those with clinical and/or echocardiographic suspicion of CA, but with this diagnosis ruled out.
Methods: We identified 544 patients with confirmed CA and 200 controls as defined above (CTRL Patients). Measurements from transthoracic echocardiograms (TTE) were performed using artificial intelligence software (Us2.AI, Singapore) and audited by an experienced echocardiographer. Receiver-operating characteristic curve analysis was used to evaluate the diagnostic performance and optimal cutoffs for the differentiation of CA patients from CTRL Patients. Additionally, a group of 174 healthy subjects (Healthy CTRL) was included to provide insight on how Patients and Healthy controls differed echocardiographically.
Results: LV GLS was more impaired (-13.9 ± 4.6% vs -15.9 ± 2.7%, p < 0.0005) and ASR was higher (2.4 ± 1.2 vs 1.7 ± 0.9, p < 0.0005) in the CA group vs. CTRL Patients. Relative wall thickness and ASR were the most accurate parameters for differentiating CA from CTRL Patients (AUC: 0.77 and 0.74, respectively). However, even with the optimal cutoff of 1.67, ASR was only 72% sensitive and 66% specific for CA, indicating presence of apical sparing in 32% of CTRL Patients and even in 6% Healthy CTRLs.
Conclusions: Apical sparing did not prove to be a CA-specific biomarker for accurate identification of CA, when compared to clinically similar controls with no CA.
Keywords: artificial intelligence; echocardiography; myocardial deformation; ventricular function.
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