Comprehensive Diagnostic Assessment of Coronary Endothelial Function Impairment and Vasospasm with Continuous Thermodilution in Patients with Suspected Coronary Microvascular and Vasomotor Dysfunction (REDEFINE-CMD)

Research summary

Angina with Non-Obstructive Coronary Arteries (ANOCA) is a common condition where patients have chest pain despite no major blockages in their heart arteries. ANOCA is caused by problems in the smaller vessels, known as coronary microvascular dysfunction (CMD), or by sudden narrowing of the arteries, called vasospasm. CMD can occur through two main mechanisms: endothelium-dependent mechanisms, where the inner lining of the vessels (the endothelium) doesn’t properly control the widening of the blood vessels or increase in blood flow when needed, or endothelium-independent mechanisms. The assessment of endothelium-independent mechanisms is currently standard of care and involves infusing saline into a heart artery and measuring blood flow changes using a standard pressure/temperature sensor-tipped guidewire and the continuous thermodilution technique. The endothelium-dependent mechanism is traditionally tested by giving a drug called acetylcholine and measuring blood flow velocity using a Doppler wire. However, Doppler wires are technically difficult and not widely available. Diagnosing vasospasm is also challenging as it relies on the presence of all three criteria of chest pain, ECG changes, and artery narrowing seen on angiography in response to acetylcholine, but these signs are somewhat subjective and don’t always appear together. Therefore, many ANOCA patients are left undiagnosed or diagnosed late, leading to repeated hospital visits, unnecessary heart tests, patient frustration, and increased healthcare costs. International cardiology guidelines recommend invasive testing to pinpoint the exact cause of ANOCA, as treatment depends on the type of dysfunction. A clear diagnosis enables tailored therapy, which can significantly improve symptoms and overall quality of life. We are studying the feasibility and reproducibility of combining continuous thermodilution and acetylcholine to assess endothelium-dependent mechanisms and vasospasm by measuring volumetric blood flow changes, coronary pressure, and resistance to provide more objective criteria for assessing these patients. This could improve accuracy and access to testing in everyday care.

Principal Investigator

Dr Giovanni Luigi De Maria

Contact us

Email: cvm_nurses@cardiov.ox.ac.uk

IRAS number

356198