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Coronary microemboli have long-term effects on regional left ventricular function: MRI 3D strain analysis

Introduction

Microembolization is common during coronary intervention in patients. The long-term effects of microemboli on regional 3D strain and global left ventricular (LV) function have not been examined.

Purpose

This experimental study investigated whether coronary microemboli have long-term deleterious effects on LV function using MRI strain analysis.

Methods

A hybrid X-ray and MRI system was used to catheterize the LAD in 6 pigs and deliver the embolic materials (40-120 μm, 250,000 count). The area at risk (AAR) was determined on first-pass perfusion (FPP) MRI before and after microembolization. Delayed enhancement (DE)-MRI and histochemical staining were used to visualize and measure microinfarcts. Analysis of longitudinal strain was performed on phase-contrast MRI and radial strain as well as global function on ssfp MRI using Segment http://segment.heiberg.se. Tagged MRI were analyzed to measure circumferential strain using HARP. The Student's t-test was used to determine if strain over the cardiac cycle differed between baseline, acute (1 h) and chronic phases (7-8 weeks).

Results

Coronary microemboli caused an acute reduction in ejection fraction (32 ± 3% vs. 50 ± 3%, P < 0.05) compared to baseline. Longitudinal strain in the AAR and remote acutely declined compared to baseline (P < 0.001, Figure), suggesting that microemboli has acute global effects. At the chronic phase the AAR displayed a partial and remote a full recovery of function compared to baseline (Figure). Radial strain also declined in the AAR (1.0 ± 7.2% vs. 58.1 ± 6.3%, P < 0.004) and remote (17.8 ± 6.8% vs. 51.1 ± 5.8%, P < 0.01) at the acute phase compared to baseline. There was a persistent decrease in the AAR but not in remote at the chronic phase (P < 0.001 and P = 0.18). On the contrary, there was a persistent decline in circumferential strain at the acute and chronic phase in the AAR compared to baseline, as well as in remote area (P < 0.001, Figure 1). FPP, DE-MRI and histopathology at postmortem confirmed the presence of microembolization and microinfarction. Microinfarcts could be detected in the acute phase as a perfusion defect on FPP but not on DE-MRI (0.1 ± 0.0%LV). No perfusion defect could be visually detected on FPP at the chronic phase but DE-MRI showed speckled hyperenhancement in the AAR. The microinfarct size was 6.6 ± 0.5%LV mass.

figure1

Figure 1

Conclusion

This serial MRI study demonstrated a persistent regional LV dysfunction in the microembolized area. Regional 3D strain measurements may be useful in predicting decreased contractility in the LV in patients with biomarker release after coronary intervention.

* P < 0.05, *** P < 0.001 compared to baseline and † p < 0.05 compared with AAR at the same stage.

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Correspondence to Robert Jablonowski.

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Open Access This article is published under license to BioMed Central Ltd. This is an Open Access article is distributed under the terms of the Creative Commons Attribution 2.0 International License (https://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Jablonowski, R., Carlsson, M., Martin, A.J. et al. Coronary microemboli have long-term effects on regional left ventricular function: MRI 3D strain analysis. J Cardiovasc Magn Reson 12, P57 (2010). https://doi.org/10.1186/1532-429X-12-S1-P57

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Keywords

  • Perfusion Defect
  • Chronic Phase
  • Longitudinal Strain
  • Circumferential Strain
  • Radial Strain