Early infarct size prediction with two-dimensional speckle tracking echocardiography compared with late gadolinium enhanced CMR

Objective

Infarct size measurement is crucial since it predicts both viability and left ventricular remodeling. A recent technique, two dimensional speckle tracking echocardiography (STE) allows accurate evaluation of myocardial deformation indices as compared to sonomicrometry and magnetic resonance imaging (MRI).

The aim of our study was to evaluate whether peak systolic longitudinal strain (SL) measured by STE was able to quantify the transmural extent of myocardial infarction (TEMI) as assessed by late contrast enhancement MRI.

Materials and methods

29 patients (55,4 ± 4,6 years, F 11/M 18) with a first reperfused myocardial infarction (MI) were included.

Echocardiography and MRI performed between day 2 and day 5 after infarction were analyzed with a 16 segment model. Segmental and global (average of segmental SL) longitudinal strain were measured by STE in apical views. Segments with MI were classified as non-transmural (TEMI<25%, TEMI<50%, TEMI<75%) and transmural MI (TEMI>75%) by late gadolinium enhanced (LGE) MRI. Infarct mass was also assessed by planimetry on LGE MRI.

Statistical analysis was performed using STATISTICA° software.

Results

464 segments were analyzed by MRI. Evaluation of SL by STE was feasible in 459/464 segments.

STE correctly identified segmental LV dysfunction induced by MI. Mean value of LS in the transmural MI segments (-8,56 ± 1,22%) was significantly lower compared to normal myocardium (-17,88 ± 0,8%) and to non-transmural MI segments (-16,43 ± 1,2% in TEMI<25% vs -12,18 ± 1,6% in 25–50%TEMI vs -11,49 ± 2,1% in 50–75%TEMI) (p < 0,001).

A significant relationship was found between the global longitudinal strain and the infarct mass measured by MRI (r = 0.61, p < 0,01). See Figure 1.

Figure 1

SL values plotted versus TEMI. A: normal myocardium, B: TEMI <25%, C: TEMI 25–49%, D: TEMI 50–74%, E: TEMI ≥ 75%.

Conclusion

Early after MI, STE evaluates both the global infarct mass by global longitudinal strain and can differentiate transmural from non transmural MI segments by segmental systolic longitudinal strain compared to LGE-MRI. This new technique is promising for early infarct size prediction.