Utility of Global Longitudinal Strain to detect significant coronary artery disease, its extent and severity in patients with stable ischemic heart disease.

BACKGROUND Early changes in cardiac function due to ischemia may be detected by global longitudinal peak systolic strain (GLS). Till date, no Indian data exist regarding role of GLS in stable ischemic heart disease (SIHD) and data showing correlation of GLS and SYNTAX score (SS) is meager in world literature. Our aim was to ascertain the role of GLS in SIHD. METHODS One hundred and seventeen subjects with angina and normal transthoracic echocardiogram (TTE) underwent strain echocardiography and coronary angiography (CAG). RESULTS There was significant correlation between GLS and SS values (R2  = .686, P < .0001). The correlation was weaker yet significant in the low SS (<22) group (R2  = .491, P < .0001) and high SS (≥22) group (R2  = .602, P < .0001). The cutoff value of GLS to detect significant CAD was -16.5 (87.6% sensitivity, 85.7% specificity, P < .0001), to predict high SS was -13.5% (sensitivity 78.3%, specificity 87.9%, P < .0001) and to predict triple vessel disease (TVD) was -14.5 (95.7% sensitivity, 73.4% specificity, P < .0001). The agreement between GLS and CAG for detection of significant CAD was substantial (κ = 0. 676, P < .0001), similar to that between territorial strain and CAG in detecting LAD disease (κ = 0.688, P < .0001) while agreement between strain imaging and CAG for detecting number of vessels diseased was moderate (κ = 0.406, P < .0001). CONCLUSION Global longitudinal peak systolic strain must be conducted on subjects with angina and inconclusive electrocardiogram (ECG) findings to rule out significant CAD even if conventional TTE was normal. This may facilitate early diagnosis of CAD or sub-clinical left ventricular systolic dysfunction (LVSD), preventive or treatment measures, and overall cost savings.