The impact of chronic total occlusion percutaneous coronary intervention on vessel physiology

Background

Chronic total occlusions (CTO) are complete coronary occlusions which can be treated with percutaneous coronary intervention (PCI) to improve anginal symptoms. Using a novel physiological index which is easily incorporated into the catheter lab after treating these patients, we set out to assess the recovery of absolute flow and collateral function in patients undergoing CTO PCI.

Aims

The primary aim was to determine the presence and degree of absolute flow recovery in patients post CTO PCI in a longitudinal analysis with two time points, immediately after CTO PCI and at a 3 month angiographic follow up.

Methods

This was a multi-centre study involving two centres in the UK and a centre in the Netherlands. A cohort of consecutive patients with CTOs involving viable myocardium underwent PCI using contemporary techniques and the hybrid algorithm. Physiological measurements were performed immediately after PCI and at a 3-month follow-up, utilizing continuous thermodilution.

Results

There is an easily measurable increase of absolute coronary blood flow and fall in microvascular resistance in the treated CTO territory which occurs between the PCI procedure and 3 months follow up. There was also a significant reduction in collateral supply to the CTO territory during the same time period. Prior CABG (coronary artery bypass grafting) and higher baseline eGFR (estimated glomerular filtration rate) were predictive of a larger change in absolute coronary flow, while utilizing an extraplaque final wire path strategy predicted a smaller but also statistically significant change.

Contribution to knowledge

This study provides evidence that the absolute coronary blood flow continue to improve over time following CTO PCI. The use of an extraplaque crossing strategy during the procedure was found to be associated with a lower change in absolute flow and served as the only independent procedural related predictor.