Dunning Classification of Coronary Artery-Aortic Dissections

The Dunning classification is specifically used to grade iatrogenic aortocoronary dissection (IACD), a rare but severe complication that occurs when an intimal tear during percutaneous coronary intervention (PCI) or diagnostic angiography extends from the coronary artery retrogradely into the aortic root. It is specific to catheter-induced injuries and should not be confused with the Stanford or DeBakey classifications, which are used to evaluate spontaneous aortic dissections.

The Classification System

Dunning divides aortocoronary dissections into three classes based on the extent of retrograde aortic involvement:

• Class I: The dissection is limited to the corresponding sinus of Valsalva (the ipsilateral aortic cusp).
• Class II: The dissection extends into the ascending aorta, but the extension is less than 40 mm.
• Class III: The dissection extends into the ascending aorta for greater than 40 mm.

Clinical Management

While the classification does not perfectly predict clinical manifestations, it provides a standard framework for determining whether to manage the complication percutaneously or surgically:

• Class I & Class II: Generally managed conservatively via percutaneous intervention. The standard approach is to rapidly deploy a stent at the coronary ostium to seal the entry point of the tear, thereby halting the propagation of the false lumen.
• Class III:Typically an indication for emergent surgical repair, as the extensive propagation carries a high risk of catastrophic aortic rupture, tamponade, or extension into the arch. However, in highly selected, hemodynamically stable cases, conservative medical management with strict blood pressure control and close tomographic follow-up has occasionally been utilized.

Original Foundational Paper

• The original diagnostic criteria and classification system were established by Dunning DW, Kahn JK, Hawkins ET, and O’Neill WW in 2000.
• The research paper is titled “Iatrogenic coronary artery dissections extending into and involving the aortic root” and was published in Catheterization and Cardiovascular Interventions.
• PubMed Reference: https://pubmed.ncbi.nlm.nih.gov/11108666/.

Recent Literature & Clinical Reviews

• A July 2026 literature review published in MDPI, titled “Morphology Matters,” discusses utilizing computed tomography (CT) or transesophageal echocardiography (TEE) to establish the most accurate Dunning classification during or immediately after a procedure.
• MDPI Link: https://www.mdpi.com/2571-841X/9/3/235.
• A recent case report documents a patient who suffered a Dunning Class III dissection following percutaneous coronary intervention for a chronic total occlusion, demonstrating that even severe classifications can occasionally be managed medically instead of surgically.
• PMC Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC13227941/.
• A January 2026 paper explores the use of intravascular ultrasound (IVUS) guidance to precisely manage IACD, reinforcing that Dunning class I indicates limited dissection while class III reflects severe aortic involvement.
• PMC Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC12956038/.