Cardiac amyloidosis screening using a relative apical sparing pattern in patients with left ventricular hypertrophy

Background Cardiac amyloidosis (CA) mimics left ventricular hypertrophy (LVH). It is treatable, but its prognosis is poor. A simple screening tool for CA would be valuable. CA is more precisely diagnosed with echocardiographic deformation parameters (e.g., relative apical sparing pattern [RASP]) than with conventional parameters. We aimed to 1) investigate incremental benefits of echocardiographic deformation parameters over established parameters for CA screening; 2) determine the resultant risk score for CA screening; and 3) externally validate the score in LVH patients. Methods We retrospectively studied 295 consecutive non-ischemic LVH patients who underwent detailed diagnostic tests. CA was diagnosed with biopsy or Tc-99m-PYP scintigraphy. The base model comprised age (>= 65 years [men], >= 70 years [women]), low voltage on the electrocardiogram, and posterior wall thickness >= 14 mm in reference to the literature. The incremental benefit of each binarized echocardiographic parameter over the base model was assessed using receiver operating characteristic curve analysis and comparisons of the area under the curve (AUC). Results Fifty-four (18%) patients had CA. RASP showed the most incremental benefit for CA screening over the base model. After conducting multiple logistic regression analysis for CA screening using four variables (RASP and base model components), a score was determined (range, 0-4 points). The score demonstrated adequate discrimination ability for CA (AUC = 0.86). This result was confirmed in another validation cohort (178 patients, AUC = 0.88). Conclusions We developed a score incorporating RASP for CA screening. This score is potentially useful in the risk stratification and management of LVH patients.