Serial cardiac magnetic resonance imaging after surgical coronary revascularization for left ventricular dysfunction

Objectives: Serial changes in segmental myocardial function after surgical myocardial revascularization have not been well demonstrated. This study was conducted to evaluate improvements in segmental myocardial function after coronary artery bypass grafting in patients with left ventricular dysfunction. Methods: Serial cardiac magnetic resonance with late gadolinium enhancement (LGE) was performed in 67 patients with left ventricular ejection fraction <= 0.35, preoperatively and at 3 months and 1 year after surgery. The wall motion score and transmural extent of LGE were evaluated on a 16-segment model. Changes in segmental myocardial function were evaluated according to the transmurality of LGE (5-point scale: grade 0 = absence of LGE, 1 = LGE 1%-25%, 2 = LGE 26%-50%, 3 = LGE 51%-75%, and 4 = LGE 76%-100%). Results: Of 908 segments in which 1-year graft patency was confirmed, 657 dysfunctional segments (378 hypokinesia, 275 akinesia, 2 dyskinesia, and 2 aneurysm) were evaluated. The LGE grades were 0, 1, 2, 3, and 4 in 235, 187, 127, 59, and 49 segments, respectively. Segmental myocardial function improved in 56.5% (371 out of 657 segments) and 58.9% (387 out of 657 segments) of dysfunctional segments at 3 months and 1 year, respectively. Of LGE grades 0, 1, 2, 3, and 4 segments, improved wall motion was observed with an inverse correlation in 71.1% (167 out of 235 segments), 55.1% (103 out of 187 segments), 49.6%(63 out of 127 segments), 40.7%(24 out of 59 segments), and 28.6%(14 out of 49 segments) at 3 months and in 74.0%(174 out of 235 segments), 57.2% (107 out of 187 segments), 52.8%(67 out of 127 segments), 44.1%(26 out of 59 segments), and 26.5% (13 out of 49 segments) at 1 year, respectively. Conclusions: One third of segments with a transmural extent of LGE>50% still had a chance for improvement after revascularization, although an inverse correlation was seen between the LGE grade and improvement of segmental myocardial function.