The Physiological Impact of CTO PCI on Coronary Pressure Measurements and Correlation in Donor Vessel

The Physiological IMPACT of Coronary Chronic Total Occlusion (CTO) Percutaneous Coronary Intervention (PCI) on Coronary Pressure --Derived Measurements, Its Correlation in the Donor Vessel and the Influence of Collateral Circulation

This study will be recording pressure wire readings from both blocked and narrowed arteries, to better guide treatment options; medications, stents or potentially bypass surgery, for patients with Chronic Total Occlusion (CTO).

The patients in this study are planned to have a Percutaneous Coronary Intervention (PCI) with recanalization of Chronic Total Occlusion (CTO) on clinical grounds alone.

This study will be recording pressure wire readings from both blocked and narrowed arteries, to better guide treatment option. To date there is no data available on instantaneous wave free ratio (iFR) measurement (a pressure derived assessment of flow limitation) in patients with blocked arteries.

Inclusion Criteria:

1. Age >18 years of age

2. Stable angina / ischaemic symptoms

3. Evidence of viability and / or ischaemia in the chronic total occlusion (CTO) territory

4. Participant is willing and able to give informed consent for participation in the study

5. Presence of a chronic total occlusion (CTO) in RCA:

   • Duration of the occlusion > 3 months;
   • Thrombolysis In Myocardial Infarction (TIMI) (50) coronary flow grade 0;
   • Spontaneously visible collaterals, Rentrop classification grade 1 or 2 or 3 from contralateral donor artery

6. Presence of minor to intermediate coronary stenosis (1-70 %) in the contralateral donor artery

7. Eligible for PCI to a chronic total occlusion (CTO)

Exclusion Criteria:

1. Previous CABG with patent grafts to the interrogated donor artery
2. Left main stenosis of > 40 %
3. Presence of severe flow limiting stenosis in the contralateral donor artery (typically > 70 % stenosis)
4. Haemodynamic instability at the time of intervention (heart rate <40 beats per minute, systolic blood pressure <90mmHg), balloon pump)
5. Significant contraindication to adenosine administration (e.g. heart block, severe asthma)
6. Contraindications to PCI
7. Severe hepatic or lung disease (chronic pulmonary obstructive disease)
8. Pregnancy
9. ACS within 48 hours of procedure
10. Severe valvular heart disease
11. Severe cardiomyopathy / Infiltrative heart disease
12. eGFR < 40