Coronary collaterals in STEMI : Incidence, time of appearance , & Impact on outcome.
Coronary collateral circulation is one of the major determinants of symptoms and outcomes in chronic CAD. But, we generally shrug off the value of coronary collateral circulation in acute coronary syndrome. The fact is, it has a myocardial mitigating effect following sudden total occlusion.
When does it appear? We did a small analysis (PDF version)
We found it is noted in 25% of patients. With reference time of appearance, 6% had it within 12hrs and in few, it was noted as early as 6 hrs. One caveat is, we may not know whether its preexisting collateral due to chronic multivessel CAD. I am sorry to note this study did not address the outcome analysis. We however documented patients with good collaterals had negligible wall motion defect and near-normal function post PCI. Some of you can pursue research in this area.
Potential role of collaterals in ACS
- It limits the infarct size
- Keep the myocardium alive and give us time to intervene
- Can converts a potential Q-MI to non-Q MI
- Possibly prevent primary VT/VF and hence dreaded sudden death in early STEMI
- Prevent early adverse remodeling of the left ventricle.
When these points appeared just my assumptions, Dr. Ali Aldujeli, (Lithuanian University of Health Sciences, Kaunas) in his presentation, at TCT 2020 confirms many of them are Indeed true
I agree, in the era of instant gratification with primary PCI, relying on coronary collaterals may appear a lesser professional virtue. Still, we may need to respect nature. Many times it bails us out.