Two-dimensional Speckle -tracking Echocardiography Derived Longitudinal Strain in Patients with Unstable Angina and Normal Left Ventricular Ejection Fraction

Longitudinal strain (LS) measurements by Speckle Tracking Echocardiography (STE) is a point of care imaging modality that had been documented to have a role in NSTEMI/STEMI and stable Coronary artery disease (CAD). This study aims to determine the accuracy of LS parameters in diagnosis and predicting severity of CAD in unstable angina patients with no regional wall motion abnormalities. It was a prospective analytical study in which 143 low-risk Unstable angina patients underwent STE. Based on Coronary angiogram results, the study participants were divided into obstructive CAD and control group. Patients with obstructive CAD (n = 79) had significantly higher GLS(Trans) and GLS(12) (-18.2 +/- 3.5% Vs -20.4 +/- 3.2%, p = 0.001 and -16.0 +/- 3.5% Vs -18.1 +/- 3.0, p = 0.001 respectively) compared to patients with normal/non-obstructive coronaries (n = 45). Both GLS(trans) and GLS(12) were independent predictors of obstructive CAD by multivariate logistic regression. However, the diagnostic accuracy of GLS(Trans) (AUC = 0.683) and GLS(12) (AUC = 0.687) were only modest. But the positive predictive value of grossly altered GLS >-16.1% was high (92.1%). Regional longitudinal strain (RLS) parameters were noted to be significantly higher in obstructive CAD group compared to the control one (RLSLAD: -18.8 +/- 4.8 Vs -21.2 +/- 4.5, p = 0.007; RLSLCX: -16.0 +/- 4.8 Vs -18.6 +/- 3.5, p = 0.001; RLSRCA: -18.8 +/- 3.6 Vs -20.2 +/- 3.4, p = 0.031). Diagnostic accuracy of GLS in patients with low-risk UA is only modest. However, the subgroup of patients with GLS >16.1% have a high probability of having obstructive CAD and in particular multivessel disease and hence these patients can be subjected to CAG without further ischemic testing.