Sequential changes of myocardial function during acute myocardial infarction, in the early and chronic phase after coronary intervention described by ultrasonic strain rate imaging.

OBJECTIVE: The aim of this prospective clinical study was to follow up patients with acute myocardial infarction from the ischemic event, over the primary coronary intervention (PCI), up to the chronic phase after survived myocardial infarction by noninvasive strain rate (SR) imaging and to determine its role in the assessment of transmurality of infarction.
METHODS: In all, 41 patients with acute S-T elevation infarction were examined immediately before, 3 days after, and 5 months after PCI. Regional myocardial function was assessed by the use of ultrasonic SR imaging and peak systolic SR and systolic strain were extracted. In addition, late-enhancement (LE) imaging with magnetic resonance imaging was done after 5 months to assess the transmurality of residual scar distribution.
RESULTS: Magnetic resonance imaging showed that 8 patients had no LE (complete recovery = no-scar group), 16 patients had subendocardial LE (nontransmural infarction = NT group), and 17 patients had a transmural LE (transmural infarction = T group) in the region of interest. Before PCI both SR and strain were markedly reduced in the ischemic segments compared with the nonischemic remote region in all 3 groups (SR: ischemia = -0.6 +/- 0.3 s(-1); remote = -1.3 +/- 0.4 s(-1), P < .001). Three days after PCI, systolic SR only increased significantly in the regions that were not transmurally infarcted. After 5 months the measurement of systolic strain could accurately distinguish the different groups. (no-scar group = -24 +/- 5%, NT group = -13 +/- 4%, T group = -1 +/- 3%).
CONCLUSIONS: This clinical study shows that with SR imaging: (1) the ischemic segment can be precisely detected; (2) the absence of transmurality early after coronary intervention can be predicted; and (3) in the chronic phase the transmurality of scar distribution can be assessed.