Presenter: Stefan Schumacher 13th Experts "Live" CTO Workshop 17th–18th September 2021 - Florence, Italy

1. Viability and Ischemia
in patients with a CTO
EURO GISE CTO 2021
Stefan Schumacher, MD
Cardiology Resident
Amsterdam UMC, location Vumc, Amsterdam, The Netherlands

2. CTO PCI vs Medical Therapy
• Large observational studies: improved prognosis and health status after successful CTO
PCI vs. failed CTO PCI or medical therapy.
• DECISION CTO trial (median 4-year FU)
• No difference in long-term prognosis
• No difference in health status
• EuroCTO trial
• No difference in long-term prognosis (3-year FU)
• Improved quality of life after CTO PCI (1-year FU)
Lee et al. Circulation 2019; Werner et al. Europen Heart Journal 2018 & presentation TCT Congress 2019

3. CTO program Amsterdam UMC
• Dedicated CTO PCI center (~175 CTO PCI procedures / year)
• Started in 2013 and ongoing
• Operators: Paul Knaapen & Alex Nap
• Technical success rate 90-95% using the hybrid algorythm
• Evaluation of clinical indication for CTO PCI in CTO team after heart team decision
• Symptoms, coronary anatomy, ischemia, viability
• During clinical work-up
• Low-threshold for viability testing by CMR
• Low-threshold for ischemia testing by [15O]H2O PET perfusion imaging

4. Eurointervention 2020
Schumacher et al. Eurointervention 2020; Schumacher et al. Eurointervention 2020

5. Collaterals and viability
‘’Collaterals cannot preserve myocardial viability’’

6. Collaterals and viability
• 218 out of 250 patients whom underwent CMR during work-up for CTO PCI in 2013-2018.
• Any documented prior MI in 118 (54%).
• Documented prior MI in the CTO area in 71 (33%).
• Excluded patients
• Non-occluded bypass graft on the CTO artery N=16
• Non-ischaemic cardiomyopathy N=7
• Signs of microvascular obstruction N=5
• Insufficient quality of CMR images N=4
• Visually assessed well-developed vs. poorly developed collaterals on ICA.
• 146 (67%) well-developed collaterals: CC score 2 and Rentrop grade 3.
• 72 (33%) poorly developed collaterals: CC score <2 or Rentrop grade <3.

7. Collaterals and viability
• Quantitative CMR analysis to evaluate the extent of myocardial viability in the CTO area.
• Observer was blinded to clinical and angiographic data
• Viability with potential for functional recovery = LGE ≤ 50% and SWT < 3mm
Standardized LV
17-segment model
Segmental wall
thickening (SWT)
Late gadolinium
enhancement (LGE)
• SWT ≥ 3mm = preserved function
• SWT < 3mm = dysfunctional
• LGE ≤ 50% = none / subendocardial
• LGE > 50% = transmural
Nijveldt et al. Journal of the American College of Cardiology 2008

8. Collaterals and viability
• Myocardial viability was predominantly present, with excessive scar observed in only 5% of CTO segments.
• Neither poorly developed collaterals nor a documented history of MI in the CTO area should be a reason
to defer a patient from considerations for CTO revascularisation.

9. Collaterals and ischemia
‘’Collaterals prevent myocardial ischemia’’

10. CTO myocardium is an ischemic zone
FFR<0.80
Invasively Non-invasively – [15O]H2O PET perfusion imaging
Hyperaemic MBF<2.3 mL∙min-1∙g-1
Sachdeva et al. Catheterization & Cardiovascular Interventions 2013; Stuijfzand et al. European Heart Journal Cardiovascular imaging 2017

11. Ischemic burden reduction after CTO PCI
• 193 patients underwent [15O]H2O PET perfusion imaging before and 3 months after
successful CTO PCI
• Definition of myocardial ischemia: Hyperaemic MBF <2.3 mL∙min-1∙g-1
• Definition of perfusion defect size (PDS): number of segments with hyperaemic MBF
• <2.3 mL∙min-1∙g-1
• <75% compared to a normal reference vascular territory (to correct for diffuse microvascular dysfunction)
Danad et al. Journal of the American College of Cardiology 2014

12. Ischemic burden reduction after CTO PCI

13. Ischemic burden reduction after CTO PCI
• Change in PDS within the CTO area compared among patients with at baseline a:
• limited perfusion defect (0-1 segment, N=15)
• moderate perfusion defect (2-3 segments, N=61)
• large perfusion defect (≥4 segments, N=117)
• Change in hyperaemic MBF compared among patients with baseline hyperaemic MBF in
the:
• Lowest tertile (N=64)
• Intermediate tertile (N=64)
• Highest tertile (N=65)

14. Ischemic burden reduction after CTO PCI

15. Summary
• Most patients have marked viability in the CTO area
• Poorly-developed collaterals and prior MI do not exclude viability
• Practically all patients (92%) had a perfusion defect ≥2 segments (>10% of the left
ventricle)
• Major reductions in ischaemic burden after CTO PCI, with more defect size reduction in
patients with a larger perfusion defect
• Hyperaemic MBF improves significantly irrespective of its baseline values (in all patients
were baseline values below threshold for ischemia)