Time-dependent change of relative apical longitudinal strain index in patients with wild-type transthyretin amyloid cardiomyopathy

AIM: This study was conducted to investigate the meaning of left ventricular (LV) apical sparing in patients with wild-type transthyretin amyloid cardiomyopathy (ATTRwt-CM). METHODS AND RESULTS: 165 patients who were diagnosed with ATTRwt-CM at Kumamoto University Hospital from January 2002 to December 2020 and had sufficient data for two-dimensional speckle tracking echocardiography were enrolled. Of these, 86 patients (52 %) had LV apical sparing (relative apical longitudinal strain index (RapLSI) > 1.0). Multivariable logistic regression analysis revealed the following variables were significantly associated with LV apical sparing: interventricular septal thickness in diastole (odds ratio (OR), 1.19; 95 % confidence interval (CI), 1.01–1.41; p < 0.05); E/e’ ratio (OR, 1.06; 95 % CI, 1.00–1.11; p < 0.05); and heart-to-contralateral ratio by (99m)Tc-labeled pyrophosphate scintigraphy (OR, 3.40; 95 % CI, 1.07–10.83; p < 0.05). Next, we compared RapLSI at the time of diagnosis with that during the follow-up period (396 days (346–458) after diagnosis) in 92 patients. RapLSI increased significantly during the follow-up period compared with RapLSI at diagnosis in the non-LV apical sparing group (0.89 ± 0.32 vs 0.74 ± 0.18, p < 0.01) but not in the LV apical sparing group (1.33 ± 0.53 vs 1.39 ± 0.45, p = 0.46). A total of 12 patients (29 %) in the non-LV apical sparing group developed LV apical sparing and 11 patients (22 %) in LV apical sparing group diminished LV apical sparing during the follow-up period. CONCLUSION: Approximately half of ATTRwt-CM patients did not have LV apical sparing at diagnosis. Because RapLSI in ATTRwt-CM significantly changed over time, repeated two-dimensional speckle tracking analysis is important for suspected ATTR-CM patients.