Each myocardial segment is represented by a circle at each time point, with larger circles denoting greater transmural extent of infarction (TEI). Mean ± standard error of the mean are displayed for each time point. Hyperemic myocardial blood flow, measured in ml/min/g, in territories subtended by a chronic total occlusion (CTO) (stenosed segments) decreased significantly with increasing TEI. At baseline, stenosed segments had significantly worse hyperemic myocardial blood flow (MBF) in all patient groups. In both intervention groups, hyperemic MBF was greater in treated segments, relative to baseline, at both 24 h (24h) and 6 months (6m) after percutaneous coronary intervention (PCI), such that the differences in hyperemic MBF between treated segments and remote segments were no longer significant. There was no change in hyperemic MBF in untreated CTO segments or remote segments. Untreated CTO segments had lower hyperemic MBF than treated CTO segments at 6-month follow-up. *p < 0.01 for comparison with baseline; p < 0.01 for comparison between stenosed and remote segments at the same time point; p < 0.01 for comparison with CTO PCI group at the same time point. MRI = magnetic resonance imaging.

Shown is a patient with CTO in the middle portion of the right coronary artery. Baseline, hyperemic MBF is reduced in the midventricular inferoseptal segment, subtended by the CTO, compared with a remote segment in the same slice (top left). Six months after PCI, hyperemic MBF in the revascularized inferoseptal segment has normalized (bottom left). Representative MRI images on the right panels are peak stress midventricular slices at corresponding imaging time points, displaying perfusion deficits in the inferoseptal and inferior segments at baseline (top, borders of the inferoseptal segment delineated by white arrows), which are no longer present 6 months after PCI (bottom). Remote anteroseptal segments are indicated by the black arrow. a.u. = arbitrary units; SI = signal intensity; other abbreviations as in Figure 1.

A patient with CTO of the middle portion of the right coronary artery. At baseline, hyperemic MBF, measured in ml/min/g, is greatly reduced in this midventricular inferior segment, subtended by the CTO, compared with a remote segment in the same slice (top left). At 6-month follow-up, hyperemic myocardial blood flow in the CTO segment remains unchanged and greatly reduced (bottom left). Magnetic resonance imaging on the right panels are midventricular slices taken at peak stress at the corresponding imaging time points, displaying perfusion deficits in the inferoseptal and inferior segments at baseline (top), which remain at 6-month follow-up (bottom). The borders of the inferoseptal segment are delineated by white arrows; the remote anterior segment is indicated by the black arrow. Abbreviations as in Figures 1 and 2.

Each myocardial segment is represented by a circle at each time point, with larger circles denoting greater TEI. Mean ± standard error of the mean are displayed for each time point. Wall thickening in territories subtended by a CTO decreased significantly with increasing TEI. At baseline, CTO segments had worse contractility than remote segments. After successful CTO PCI, wall thickening in treated segments improved, such that, after simultaneous adjustment of wall thickening by TEI, the differences between treated segments and remote segments were no longer significant at 24 and 6 months after PCI. Improvement in contractility was less likely in segments with greater TEI before PCI. In patients scheduled for non-CTO PCI, wall thickening improved only at 6 months, relative to baseline. There was no change in wall thickening in untreated CTO segments or remote segments. Untreated CTO segments had significantly worse wall thickening than treated CTO segments at 6-month follow-up. *p < 0.01 for comparison with baseline; p < 0.01 for comparison between stenosed and remote segments at the same time point; p < 0.05 for comparison with CTO PCI group at the same time point. Abbreviations as in Figure 1.