Echocardiographic score for the screening of cardiac amyloidosis with positive 99m technetium pyrophosphate scintigraphy result

Introduction: Speckle-tracking-derived strains in cardiac chambers may provide better solutions for transthyretin amyloid cardiomyopathy (ATTR-CM) screening. This study aimed to evaluate the efficacy of biventricular strain measurements using speckle tracking for screening ^99m Tc-pyrophosphate (^99m Tc-PYP) scintigraphy-positive cardiomyopathy, which is nearly equivalent to ATTR-CM.

Methods: We performed a retrospective analysis of transthoracic echocardiographic studies using vendor-independent speckle tracking analysis in older patients (≥65 years) who underwent ^99m Tc-PYP scintigraphy to evaluate the etiology of suspected ATTR-CM in our institute between January 2019 and December 2022.

Results: The entire cohort (n = 89) was divided into two subgroups positive ^99m Tc-PYP scan results (n = 34) and negative ^99m Tc-PYP scan results (n = 55). In the multivariate analysis, posterior wall thickness (p = .003, odds ratio [OR]:1.48, 95% confidence interval [CI]:1.14 -1.92), left ventricular longitudinal strain apical/basal ratio (LVLSapi/bas) (p = .015, OR: 2.78, 95% CI: 1.23-6.32, and right ventricular longitudinal strain (RVLS) (p = .003, OR: 1.15, 95% CI: 1.05 -1.26) were selected to be the most representative echocardiographic findings in ^99m Tc-PYP positive cardiomyopathy. The receiver operating characteristic analysis indicated that posterior wall thickness (p < .0001, area under the curve [AUC]: .821, cut-off value: 14.0 mm), LVLSapi/bas (p < .001, AUC: .802, cut-off value: 2,16), and RVLS (p < .001, AUC: .791, cut-off value: -18.7%) could significantly detect ^99m Tc-PYP positive results with an excellent credibility. Echocardiographic score points calculated using the summary of these three parameters in each patient revealed that a 2-point score had a fair sensitivity (85%) and an excellent specificity (93%), while a 1-point score had an excellent sensitivity (91%) and a modest specificity (53%).

Conclusion: Our proposed echocardiographic screening tool for ^99m Tc-PYP scintigraphy-positive cardiomyopathy may help clinicians manage patients with suspected ATTR-CM.