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Improvement of LV functional performance in the chronic total coronary occlusion during the late stage is associated with the extensive collateral development
Journal of Cardiovascular Magnetic Resonance volume 13, Article number: O52 (2011)
To investigate whether left ventricular (LV) function and regional wall motion improvement are associated with the extent of collateral development in coronary chronic total occlusion (CTO).
In nine pigs a CTO was created by percutaneously inserting a fibrin plug (AngiosealΤΜ) into the mid-to-distal left anterior descending artery (LAD). Animals were studied six (n=3) or twelve weeks (n=6) later prior to sacrifice. An x-ray angiogram confirmed the LAD CTO at those time points. Cardiac MR (CMR) studies were then conducted on a 1.5T (n=6) or on a 3.0T MRI system (n=3), which included SSFP short axis sections for wall motion and post-gadolinium LGE-MRIs for viability. After sacrifice, both right and left coronary systems were injected with Microfil. X-ray or MSCT angiography of the fixed heart was obtained. A longitudinal cardiac section including the CTO lesion, proximal/distal LAD and the borders of infarction was removed and prepared in gel, then imaged in a micro-CT system at 27 micron resolution. LV functional parameters including wall thickness at end-systole (WTES) and end-diastole (WTED) were measured in border zone, infarct and remote region. Systolic wall thickening (SWT) was calculated using as (WTES-WTED) x100/WTED. CMR and micro-CT data were processed using commercial software. The extent of collaterals on micro-CT images was rated qualitatively using a score from 0 to 3, indicating that no, minimal, moderate, or extensive collaterals were observed. A Student’s t-test was used for the statistical significance of differences between measurements at 6 and 12 weeks.
LGE-MRI determined the presence of LV myocardial infarction (MI). Tables 1 and 2 summarize the results of global and regional LV function measurements at both time points. Ejection fraction (LVEF) at 12 weeks was significantly greater than at 6 weeks (39.45±5.38% vs. 26.27±5.77%, P=0.01) although the extent of infarct was similar between these two groups (P=0.16). In border zone the WTES (11.31±1.72 vs. 8.67±0.57mm, P=0.04) and SWT (68.31±11.55% vs. 35.87±19.14%, P=0.01) increased at 12 versus 6 weeks. On the visual scores of collateral development, between 6 and 12 weeks, there was an increase in collateral number (1.33±0.58 vs. 2.83±0.41, p<0.003). Figure 1 similarly illustrates increased collateral development at the later time point.
Extensive collateral development during the late stage of myocardial repair after CTO may contribute to LV functional improvement through increased SWT in the border zone. This provides a potential explanation for preserved LV function witnessed in some patients with CTO.
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Yang, Y., Strauss, B., Qiang, B. et al. Improvement of LV functional performance in the chronic total coronary occlusion during the late stage is associated with the extensive collateral development. J Cardiovasc Magn Reson 13 (Suppl 1), O52 (2011). https://doi.org/10.1186/1532-429X-13-S1-O52
- Leave Anterior Descend
- Border Zone
- Chronic Total Occlusion
- Regional Left Ventricular Function
- Preserve Left Ventricular