What is the risk of ACS after PCI in a CTO related artery ?

What is the risk of ACS after PCI in a CTO related artery ?

March 16, 2024 by dr s venkatesan

CTOs are opened primarily for four reasons

• Angina which is refractory to drugs
• Stress test positivity with or without angina
• Anxiety of having a blocked coronary artery in a self educated patient
• Cardiologist’s clandestine pride & pursuit*

* Personal experience included

Some evidence based observation

Most of the studies as on today do not give survival advantage of opening a CTO.(DECISION-CTO,EURO-CTO,EXPLORE,IMPACTOR)

Opening a CTO, for reasons other than angina (i.e. for relief of dyspnea or improving functional capacity) is largely conjectural and based on randomly accrued data backed by poor interpretation. The role of collateral circulation in CTO that can compensate even during exercise is well known at patient level data. This has become a difficult area of research because it involves spending more time with the patient, and hence not studied much. We are in the era of artificial intelligence ,virtual patients and statistical extrapolations that can steer the Kaplan Meyer curves in the desired direction.

Pure academicians shall follow the current guidelines. Surprise… surprise !, There is some good news. The normally aggressive American guidelines exercise much caution with a 2B punch. Still , even today it is weird to see hours of academic time is consumed in CTO Interventions in any interventional cardiology meets. (May be , they could get a breakthrough benefit , which I couldn’t appreciate)

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CTO-PCI follow up

The incidence of MACE including ACS varies between 12-28% depending on LV function.(Ref 2) How about Conferring 12% risk of ACS in a person who has normal LV by doing CTO-PCI ? Still it continue to be a smart move for many of us ? This is exactly the reason experts are struggling to come to term with truths behind negativity of most published CTO trials.

Image from Ref 2  Egypt Heart J 72, 28 (2020

Now, answer to the title question. What is the future risk of ACS in opening CTO related artery ?

Asymptomatic CTOs, with fair excercise capacity, should probably never be opened for the simple reason, a closed artery is naturally protected, against a future ACS at least in its territory

Final message

Currently, in the science of cardiac revascularization there is only evidence and it’s Interpretations, little patient level facts.

Reference

1. Hamzaraj K,Patient Selection and Clinical Indication for Chronic Total Occlusion Revascularization-A Workflow Focusing on Non-Invasive Cardiac Imaging. Life (Basel). 2022 Dec 20;13(1):4.)

2.El Awady, W.S., Samy, M., Al-Daydamony, M.M. et al. Periprocedural and clinical outcomes of percutaneous coronary intervention of chronic total occlusions in patients with low- and mid-range ejection fractions. Egypt Heart J 72, 28 (2020). https://doi.org/10.1186/s43044-020-00065-1

Post-amble

Living with a single coronary artery, is potentially a frightening scenario for the patient* which has to supply its own area and also, need to donate the occluded coronary artery . What will happen if a single donor (RCA/LCX) gets closed? One more remote risk in CTO is, acute collateral shutdown causing STEMI/NSTEMI. These statistically minuscule risks are well exploited by coronary caretakers. Meanwhile, there is little talk about the chances of CTO getting closed by itself after an apparently successful PCI. The consequences of anatomic and hemodynamic collapse of hitherto well flowing collaterals , after a CTO PCI will require a separate discussion.

*It is wiser to recall , left coronary artery is also single before bifurcating. Surviving an entire life span with a single10-20 mm tunnel called left main, rarely elicit the same fear in us.