Objectives: To compare infarct size and left ventricular ejection fraction in patients with non-ST-elevation myocardial infarction (NSTEMI) with and without acute coronary occlusions, and determine if myocardial strain by speckle-tracking echocardiography can identify acute occlusions in patients presenting with non-ST-elevation acute coronary syndrome (NSTE-ACS).
Methods: 111 patients with suspected NSTE-ACS were enrolled shortly after admittance. Echocardiographic measurements were performed a median of 1 h (interquartile range 0.5-4) after admittance, and coronary angiography 36 ± 21 h after onset of symptoms. Territorial longitudinal and circumferential strain was calculated based on the perfusion territories of the three major coronary arteries in a 16-segment model of the left ventricle, and compared with traditional echocardiographic parameters. Long-term follow-up was by echocardiography and contrast-enhanced magnetic resonance imaging (ceMRI).
Results: Patients with NSTEMI due to acute coronary occlusion had higher peak troponin T than patients with NSTEMI without acute occlusions (4.9 ± 4.7 vs 0.9 ± 1.1 μg/l, p<0.001), larger infarct size by ceMRI (13 ± 8% vs 3 ± 3%, p<0.001) and poorer left ventricular ejection fraction (48 ± 6% vs 57 ± 6%, p<0.001) at follow-up. Territorial circumferential strain was the best parameter for predicting acute coronary occlusion. A territorial circumferential strain value >-10.0% had 90% sensitivity, 88% specificity and area under the curve=0.93 for identification of acute occlusions.
Conclusions: Patients with NSTEMI due to acute coronary occlusions develop larger infarcts and more impaired left ventricular function than patients with NSTEMI without occlusions, regardless of infarct-related territory. Territorial circumferential strain by echocardiography enables very early identification of acute coronary occlusions in patients with NSTE-ACS and may be used for detection of patients requiring urgent revascularisation.