Comparison Of Regional Circumferential Strain By Different Speckle Tracking Methods With Tagged Mri In Patients With Left Bundle Branch Block

Background: The application of speckle tracking echocardiography has shifted towards global longitudinal strain, despite its potential to measure regional strain. Especially in left bundle branch block (LBBB) patients these often complex, regional strain patterns are of importance. Methods: Twenty-one LBBB patients, with a median LVEF of 29%, were examined by using tagged magnetic resonance imaging (MRI) and echocardiography. Circumferential strain curves were measured and correlated by using commercially software (QLAB), an in-house block matching technique (PULS/IT), and MRI. Septal rebound stretch (SRS) was also determined. Results: Compared with MRI, there is good correlation for both global circumferential strain (r=0.98 and r=0.97 for QLAB and PULS/IT, respectively) and lateral wall circumferential strain (r=0.95 for both techniques). For septal circumferential strain however, correlation with MRI is poor (r=-0.19 and r=0.49 for QLAB and PULS/IT respectively). SRS correlates poorly with MRI irrespective of the method used (r=0.40, r=0.29 for QLAB and PULS/IT respectively). Minimal Fourier regularization of our method (PULS/ITfit) did reduce the standard deviation of error, albeit with reduced correlation for septal strain. Conclusion: In patients with LBBB, speckle tracking algorithms do not accurately determine septal circumferential strain. Given the need for reliable measure of regional strain, further research and refinement of these contemporary algorithms is needed.