The global myocardial work index (GWI) can be used to differentiate wild-type transthyretin amyloid cardiomyopathy (ATTR-CM) with aortic stenosis from aortic stenosis of different etiology as well as to predict survival in patients with ATTR-CM, according to a study published in Echocardiography.
The study was designed to evaluate the role of echocardiographic parameters in patients with ATTR-CM and aortic stenosis vs patients with aortic stenosis without ATTR-CM and to assess the role of myocardial work in the prognosis of patients with ATTR-CM.
The researchers recruited a cohort of 212 patients with ATTR-CM, including 50 patients with ATTR-CM and aortic stenosis, and another cohort of 354 patients with aortic stenosis of different etiology.
They used receiver-operated characteristic curves and area under the curve to measure the sensitivity and specificity of GWI, the relative apical sparing ratio, the apical-to-basal ratio, and the ejection fraction-to-global longitudinal strain ratio. Multivariable regression was used to assess the prognostic value of GWI in patients with ATTR-CM.
Read more about ATTR-CM testing
According to the results, the sensitivity and specificity of GWI for differentiating ATTR-CM and aortic stenosis vs just aortic stenosis were 80% and 70%, respectively. The area under the curve of GWI was larger than that of the apical-to-basal ratio (P =.01) and ejection fraction-to-global longitudinal strain ratio (P >.01) but not the relative apical sparing ratio (P =.15).
Moreover, multivariable regression found age-predicted mortality with an estimated hazard ratio (HR) of 1.086 (CI, 1.034-1.141), while GWI predicted survival with an estimated HR of 0.837 (CI, 0.733-0.956) per 100 mm Hg*% increase in patients with ATTR-CM.
“Measurement of GWI is both easily obtainable and of low cost since all that is needed is to apply the blood pressure of the patients to the strain analysis. However, studies designed specifically to examine the role of myocardial work in the differentiation of ATTR-CM from other causes of myocardial wall thickening are needed to truly determine its value in a clinical setting,” Ladefoged and colleagues noted.
ATTR-CM, a frequent cause of heart failure in the elderly population, is difficult to differentiate from other causes of heart hypertrophy. Before this study, echocardiographic parameters were examined in small samples of mixed cardiac amyloidosis.
Reference
Ladefoged B, Pedersen ALD, Clemmensen TS, Poulsen SH. Strain-derived myocardial work in wild-type transthyretin cardiac amyloidosis with aortic stenosis-diagnosis and prognosis. Echocardiography. Published online August 25, 2023. doi:10.1111/echo.15681
