Figure 1. shows the bull’s eye pattern of global longitudinal strain with the typical pattern of a decreasing gradient of strain from apex to base or what is termed apical sparing. In a study by Phelan et al. (ref.) the bull’s eye map of longitudinal strain was divided into three rings: the basal, mid-ventricular and apical rings. A relative apical longitudinal strain was calculated as follows:
Relative apical LS = (average apical LS/ (average basal LS + mid-LS)
I55 consecutive patients with cardiac amyloidosis (CA) were compared with 30 control patients with LV hypertrophy (n=15 with hypertrophic cardiomyopathy, n=15 with aortic stenosis).
A value relative apical (LS) of >1.0 was sensitive (93%) and specific (82%) in differentiating CA from controls (area under the curve 0.94).
In a logistic regression multivariate analysis, relative apical LS was the only parameter predictive of CA (p=0.004). Only relative apical LS was found to be significantly predictive of CA (p<0.004) using multivariable logistic regression analysis with the diagnosis of CA as the outcome variable and the following as predictors: age, gender, New York Heart Association grade, a history of hypertension or diabetes, EF, E/e’, E/A, DT, global LS, peak gradient across the aortic valve, low voltage on ECG and relative apical LS.
In the above case performing the above calculation on the GLS values in the bull’s eye map above, would yield a ratio of 1.22 which is highly in favor of cardiac amyloidosis.
Dermot Phelan, Patrick Collier, Paaladinesh Thavendiranathan, Zoran B Popovic, Mazen Hanna, Juan Carlos Plana, Thomas H Marwick, James D Thomas
Relative apical sparing of longitudinal strain using two-dimensional speckle-tracking echocardiography is both sensitive and specific for the diagnosis of cardiac amyloidosis