Myocardial change with microvasculer obstruction after acute myocardial infarction

Introduction

Microvascular obstruction detected by Cardiovascular Magnetic Resonance (CMR) has been linked to ventricular remodeling and adverse cardiovascular events in acute myocardial infarction (AMI).

Purpose

We analyzed how the changes of myocardium with MVO in human reperfused myocardium affect left ventricular function by using two imaging modalities, CMR and cardiac nuclear imaging.

Methods

We investigated 28 patients with anterior AMI in whom primary percutaneous coronary intervention was performed successfully (mean age : 63.4 +- 8.4 year old, female 14.3%). From nuclear imaging, ejection fraction (LVEF), left ventricular volumes, and summed defect score (SDS) 2 weeks and 3 months post-MI were obtained by using rest gated technetium-99 m tetrofosmin electrocardiography-gated single photon emission computed tomography. Gdlinium contrast enhancement CMR imaging was performed within 2 weeks after AMI using a 1.5 T imaging unit. The patient's characteristics and cardiac parameters were compared between two groups: with MVO (group M, n = 18) and without MVO (group nM, n = 10).

Results

Both groups had similar baseline characteristics about coronary risk factors. In group M, peak CK was higher (7208 IU/L and 3929 IU/L, P < 0.01) and reperfusion time was shorter (4.7 hr and 3.7 hr, P < 0.01) tnan group nM. Left ventricular end-diastolic volume (LVEDV) (142 ml and 134 ml, P < 0.01) and SDS (33 and 20, p < 0.05) showed significantly larger in early phase of AMI in group M. Although LVEDV at three months after AMI kept larger value (149 ml and 128 ml, p < 0.01) in group M, LVEF weren't different in each group. The improvement of LVEF was also remarkably larger in group M (21% and 9%). Any medication such as beta blocking agents and angiotensin converting enzyme inhibitors didn't affect these results. See Table 1.

Table 1 Cardiac performance

Conclusion

Although MVO detected by CMR predict the ventricular remodeling even in successful coronary intervention, this adaptation is thought to increase cardiac output to some extent.