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Changes in absolute flow, myocardial resistance and FFR after chronic total occlusion percutaneous coronary
Sarosh A Khan1,2, Osama Alsanjari1,2, Daniëlle C J Keulards3
1Essex Cardiothoracic Centre, Basildon University Hospital, Basildon, UK.
Insights
Coronary blood flow improves significantly three months after percutaneous coronary intervention (PCI) for chronic total occlusion (CTO). Patient factors like prior coronary artery bypass grafting (CABG) and kidney function influence outcomes more than procedural choices.
Area of Science:
- Cardiovascular Medicine
- Interventional Cardiology
- Physiology
Background:
- Outcomes of percutaneous coronary intervention (PCI) for chronic total occlusion (CTO) remain inconsistent.
- A deeper understanding of coronary physiology in CTO patients is needed.
- This study aimed to measure absolute coronary blood flow recovery post-PCI in CTO patients.
Purpose of the Study:
- To assess the recovery of absolute coronary blood flow after successful CTO PCI.
- To identify patient and procedural factors associated with favorable physiological outcomes.
Main Methods:
- Prospective observational study of 81 patients undergoing CTO PCI.
- Physiological measurements using continuous thermodilution were taken immediately post-PCI and at 3-month follow-up.
- Contemporary PCI techniques and the hybrid algorithm were employed.
Main Results:
- Absolute coronary blood flow increased by 30% and microvascular resistance decreased by 16% from immediately post-PCI to 3-month follow-up.
- Fractional flow reserve (FFR) showed a significant increase.
- Prior coronary artery bypass graft (CABG) and higher estimated glomerular filtration rate (eGFR) were linked to greater flow improvement.
Conclusions:
- Coronary blood flow continues to improve, and microvascular resistance decreases up to 3 months post-CTO PCI.
- Patient characteristics, including prior CABG and eGFR, were stronger predictors of flow change than procedural factors.
- An extraplaque strategy was associated with less improvement in absolute flow.
Background:
Randomised studies of percutaneous coronary intervention (PCI) in patients with chronic total occlusion (CTO) have shown inconsistent outcomes, suggesting incomplete understanding of this cohort and their coronary physiology. To address this shortcoming, we designed a prospective observational study to measure the recovery of absolute coronary blood flow following successful CTO PCI Aims: We sought to identify patient and procedural characteristics associated with a favourable physiological outcome after CTO PCI.
Methods:
Consecutive patients with a CTO subtending viable myocardium underwent PCI utilising contemporary techniques and the hybrid algorithm. Immediately after PCI, and at 3-month follow-up, physiological measurements were performed utilising continuous thermodilution.
Results:
A total of 81 patients were included with a mean age of 63.6±8.9 years, and 66 (81.5%) were male. Physiological measurements of absolute coronary blood flow in the CTO vessel increased by 30% (p<0.001) and microvascular resistance reduced by 16% (p<0.001) from immediately post-CTO PCI to follow-up assessment. Fractional flow reserve increased by 0.02 (p=0.015) in the same period. Prior coronary artery bypass graft (CABG) and a higher estimated glomerular filtration rate (eGFR) were associated with a larger change in absolute flow. An extraplaque strategy was associated with a smaller change in absolute flow.
Conclusions:
Post-CTO PCI, there is a continued augmentation in absolute coronary blood flow and reduction in microvascular resistance from baseline to follow-up at 3 months. Prior CABG and a higher baseline eGFR were predictors of a larger change in absolute coronary flow, whilst an extraplaque final wire path strategy predicted a smaller change. Lastly, the patient characteristics and comorbidities had a larger influence than procedural factors on the observed change in absolute flow.
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