Inter-vendor comparison of left atrial strain using layer specific strain analysis.

Left atrial strain (LAS) on transthoracic echocardiogram (TTE) is increasingly recognised to have clinical utility in cardiovascular disease. Differences in LAS measurements between vendors remains a barrier for clinical use. We sought to compare LAS between two commonly used software platforms; the layer-specific endocardial and mid-myocardial measurements of LAS on General Electric (GE) Echopac were compared to TomTec strain. LAS was measured in 88 individuals with no previous cardiac history and 40 paroxysmal AF (PAF) patients, in sinus rhythm at TTE. Conventionally, LAS measured using GE Echopac is mid-myocardial strain (GE-mid); additionally, endocardial (GE-endo) LAS was evaluated. Both LAS measurements by GE were compared to TomTec-Arena (v2.30.02) measurements. Reservoir (ƐR), contractile (ƐCT) and conduit (ƐCD) phasic strain were evaluated. Both GE-mid and GE-endo LAS correlated well with TomTec LAS. On Bland-Altman analysis, GE-mid LAS measurements were systematically lower than TomTec LAS (ƐR: mean difference (MD) - 6.08%, limits of agreement (LOA) - 12%, 0%, ƐCT: MD - 0.8%, LOA - 7%, 5%, ƐCD: MD - 5.2% LOA - 12%, 1%). GE-endo LAS demonstrated no systematic difference from TomTec LAS, but had wider limits of agreement (ƐR: MD 0.41%, LOA - 7%, 8%, ƐCT: MD 0.50%, LOA - 6%, 7%, ƐCD: MD - 0.08%, LOA - 7%, 7%). ƐR had the best reproducibility. Mid-myocardial LAS, routinely evaluated by GE Echopac software, systematically underestimates LAS compared to TomTec. Using GE endocardial LAS eliminated this bias, but introduced greater variation between measurements. Serial measurements of LAS should therefore be performed on the same vendor system.