Natural Bypass Score May Guide Care in Chronic Coronary Blockages

 

Researchers at the University of East Anglia (Norwich, UK), working with Norfolk and Norwich University Hospital, evaluated the Rentrop collateral score, an angiographic grading system of coronary “natural bypass” vessels. The score is derived during routine coronary angiography and reflects the effectiveness of collateral flow to myocardium beyond an occlusion. The investigation asked whether this readily available measure can indicate myocardial viability without immediate reliance on advanced imaging. 

 

Investigators analyzed patients with chronic total occlusion, defined as a completely blocked coronary artery persisting for months. They compared the Rentrop score with cardiac magnetic resonance imaging (MRI), regarded as the reference standard for distinguishing viable from permanently scarred myocardium. The analysis assessed how collateral grade aligned with downstream tissue viability. 

 

The cohort included 56 patients with completely occluded coronary arteries. Patients with stronger collateralization, defined as a Rentrop score above one, were more likely to have living myocardium despite the blockage. The Rentrop score was the only independent predictor of viability, and each one-step increase more than doubled the likelihood that the affected myocardium remained alive. Findings were published on May 31, 2026, in Open Heart, in a study led by the University of East Anglia with the Norfolk and Norwich University Hospitals NHS Foundation Trust and Leiden University Medical Centre. 

 

Opening a completely blocked artery is described as long, complex, and resource‑intensive, and not every patient benefits. Using information already visible on an angiogram could help clinicians decide who warrants further testing, prioritize MRI for those most likely to benefit, and avoid unnecessary procedures. The approach may be especially useful in settings where immediate access to cardiac MRI is limited. 

 

“We hope that our work could help doctors make faster, more informed decisions in the catheter laboratory, especially when advanced cardiac MRI is not immediately available. By simply looking at what’s already visible during a routine angiogram, doctors can quickly identify patients worth investigating further, prioritize MRI scans for those who need them most and avoid unnecessary procedures in patients unlikely to benefit. In other words, it could mean faster decisions, fewer risks, and better outcomes,” said Dr. Pankaj Garg, from UEA’s Norwich Medical School and a consultant cardiologist at the Norfolk and Norwich University Hospital.

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UEA’s Norwich Medical School