P866
Effects of successful percutaneous coronary intervention of chronic total occlusions on myocardial perfusion and left ventricular function

Background: Chronic total occlusions (CTO) are observed in up to 30% of patients with known or suspected coronary artery disease. Percutaneous coronary intervention (PCI) of CTO is technically challenging and its salutary effects are questioned.

Purpose: The aim of the present study was to investigate the effects of successful PCI CTO on absolute myocardial blood flow (MBF) and functional recovery.

Methods: Patients with a documented CTO were prospectively examined for ischemia and viability with (15O)H2O positron emission tomography (PET) and late gadolinium enhancement cardiac magnetic resonance imaging (LGE-CMR). Sixty-nine consecutive patients, in whom PCI was successful, underwent follow-up PET and CMR after approximately 12 weeks to evaluate potential improvement of MBF as well as regional and global systolic function.

Results: After PCI, stress MBF in the CTO area increased from 1.22±0.36 to 2.40±0.90 mL·min-1·g-1 (p<0.001), whilst stress MBF in the remote area also increased significantly between baseline and follow-up PET (2.58±0.68 to 2.77±0.77 mL·min-1·g-1, p=0.01). The ratio of stress MBF between CTO and remote area was 0.49±0.13 at baseline and increased to 0.87±0.24 at follow-up (p<0.001). MBF defect size of the CTO area decreased from 5.12±1.69 to 1.91±1.75 myocardial segments after PCI (p<0.001). Left ventricular ejection fraction significantly increased (46.4±11.0 vs. 47.5±11.4%, p=0.01) at follow-up, whereas mean systolic wall thickening of the myocardium subtended by the CTO artery did not improve after PCI (p=0.18). There was no relation between the extent of LGE (%) and change of systolic wall thickening at follow up (R=0.01, p=0.69), nor was improvement in stress MBF associated with recovery of systolic wall thickening (R=0.08, p=0.53).

Conclusions: The vast majority of CTO patients with documented ischemia and viability showed significant improvement in stress MBF and a reduction of ischemic burden after successful percutaneous revascularization with only minimal effect on left ventricular ejection fraction.