The role of segmental and global longitudinal strain in identifying culprit lesion localization in NSTEMI patients with preserved ejection fraction

In NSTEMI with preserved ejection fraction, conventional echocardiography frequently fails to demonstrate overt regional wall motion abnormalities despite clinically relevant coronary stenosis, limiting early anatomical targeting. Two-dimensional speckle-tracking echocardiography (STE) quantifies myocardial deformation and may reveal subtle, predominantly subendocardial, ischaemia-related dysfunction. A rapid, pre-angiography strain “map” could therefore support culprit territory localisation when standard imaging appears unremarkable. To assess whether global longitudinal strain (GLS) and territorial/segmental longitudinal strain derived from STE identify the angiographic culprit vessel in NSTEMI with preserved ejection fraction, and to quantify the relationship between strain impairment and stenosis severity. We analysed 100 consecutive NSTEMI patients undergoing early coronary angiography at a single centre (January 2019–January 2020). NSTEMI was defined by serial high-sensitivity troponin I (hs-TnI) measurements demonstrating a rise/fall pattern alongside clinical evidence of myocardial ischaemia. Speckle-tracking echocardiography was performed approximately 1 hour before angiography using a standard 17-segment model. Two experienced readers, blinded to clinical and angiographic data, quantified GLS and territorial longitudinal strain assigned to LAD, LCx, and RCA perfusion territories. Angiography was performed within 24 hours. Two blinded invasive cardiologists determined culprit vessel and stenosis severity. We assessed associations between stenosis severity and GLS/territorial strain using linear models and reported model fit (R²). Mean age was 57.8±12.6 years; 66.3% were male; mean ejection fraction was 59.8±3.0%. GLS was −17.5±0.6%. Territorial strain demonstrated a clear gradient consistent with culprit-territory dysfunction: strain was most impaired in the LAD territory (−16.8±2.3%) compared with LCx (−17.8±1.8%) and RCA territories (−18.8±2.2%). Culprit lesions were located in LAD (56%), LCx (29%), and RCA (15%). Mean stenosis severity was 89.4±10.5%. Stenosis severity showed only a weak association with GLS (R²=0.125), whereas territorial strain exhibited substantially stronger associations, particularly in the RCA and LCx territories (R²=0.334 for LAD, 0.488 for LCx, and 0.638 for RCA). In NSTEMI with preserved ejection fraction, pre-angiography territorial strain mapping shows territory-specific impairment and relates to stenosis severity more strongly than GLS. Territorial/segmental strain analysis may enhance early culprit territory localisation and assist anatomical targeting when conventional echocardiography appears normal.