Early systolic lengthening may identify minimal myocardial damage in patients with non-ST-elevation acute coronary syndrome

Abstract

Aims: Ischaemic myocardial segments tend to stretch as the intraventricular pressure rises steeply during the isovolemic contraction phase, before they contract during ejection. We hypothesized that the time they remain stretched, called duration of early systolic lengthening (DESL), correlates with final infarct size as defined by contrast enhanced magnetic resonance imaging (CE-MRI). We also assessed whether DESL could identify patients with acute coronary occlusion, and compared it with traditional measures for myocardial function.

Methods and results: In this retrospective study, 150 consecutive patients with Non-ST-elevation acute coronary syndrome (NSTE-ACS) referred for coronary angiography were included. Speckle tracking echocardiography was performed prior to angiography to determine DESL. The final infarct size was quantified at follow-up 9 ± 3 months after initial admission in 61 patients and echocardiography performed in 143 patients. DESL showed good correlation with the final infarct size (r = 0.67, P < 0.001). Thirteen patients had no visible sign of infarct on CE-MRI (minimal myocardial damage), and DESL was significantly shorter in these patients than in patients with signs of infarct (27 ± 19 vs. 84 ± 41 ms, P < 0.001). Compared with left ventricular ejection fraction, wall motion score index, and global longitudinal strain, DESL showed the best accuracy in detecting patients with minimal myocardial damage, with an area under the receiver operating characteristic curve of 0.92 (0.82 to 0.99, P < 0.001). DESL was more prolonged in patients with coronary occlusions, compared with those without occlusions (86 ± 45 vs. 63 ± 31 ms, P < 0.01). DESL was significantly shorter at follow-up, compared with baseline (P = 0.04).

Conclusions: DESL could identify patients with minimal myocardial damage, differentiate between occlusion and non-occlusion, and may be helpful in the risk stratification of patients with NSTE-ACS.

Keywords: echocardiography; magnetic resonance imaging; myocardial infarction.