Changes in left ventricular function and wall motion determined by cardiac magnetic resonance imaging after successful recanalization of true chronic total occlusion in native coronary arteries

Abstract

Purpose: True CTOs are defined by a thrombolysis in myocardial infarction flow 0 and duration of the occlusion of more than 3 months. In those lesions, successful recanalization reduced angina pain. We used cardiac magnetic resonance imaging (cMRI) to evaluate the effect of successful true CTO recanalization on left ventricular (LV) function and regional wall motion. Methods: Gadolinium contrast enhanced cMRI was performed on a 1.5 Tesla scanner in 43 patients who underwent successful recanalization of a true CTO in a native coronary artery by percutaneous coronary angioplasty. CMRI was performed prior to recanalization and repeated after 6 months. CTO was located in LAD (N=16, 37.2%), CX artery (N=9, 20.9%) or RCA (N=18, 41.9%). After successful balloon dilation drug-eluting stents with a mean stent length of 78.6±43.8mm (range 18-188mm) were implanted. In the cMRI short-axis views were split according to the 17-Segment model of the American Heart Association. For each segment the wall thickness (WT) was measured over the duration of one heart cycle and segmental WT (SWT) was calculated using the Formula SWT=(WTmax-WTmin)/WTmin. Results: In the total population cMRI showed a non-significant increase in LV ejection fraction (LVEF), as well as non-significant decreases in LV enddiastolic and endsystolic volumes. Improvement in LVEF (Δ+4.1%) was seven times higher in patients with a LVEF below the median compared with patients with a LVEF above the median (Δ+0.6%) at baseline CMRI (p<0.001). Improvement in LVEF in patients without scar tissue (Δ+3.2%) was higher than in patients with scar tissue (Δ+0.7%, p=0.029) in the target myocardium. 231 (33.5%) myocardial segments were located in the perfusion territories of the target vessel. SWT improved in all target segments significantly from 73.3±36.0% to 78.6±40.5% (p=0.008). Dysfunctional segments \[SWT<45% at baseline\] (N=58, 25.1%) showed a greater improvement in SWT (Δ+13.3%) than functional segments (Δ+2.7%, p=0.021). Segments without scar tissue (N=92) showed a significant improvement in SWT (Δ+9.2%, p=0.004). The greatest benefit of revascularisation on SWT was found in dysfunctional segments without scar tissue present (N=17, 7.4%, SWT Δ+16.6%, p=0.017). Conclusions: Successful recanalization of true CTOs in native coronary arteries is associated with a significant improvement of LVEF in patients with low baseline LVEF as well as in patients without scar tissue in the perfusion territory. Furthermore, successful true CTO recanalization is associated with a significant increase in segmental wall thickening in dysfunction segments without scar tissue.