An Introduction to iFR: Concepts, Principals, and Limitations - Dr. Justin Davies

Summary

Dr Justin Davies, Consultant Cardiologist, Imperial College London, UK

Dr Justin Davies introduces iFR (Instantaneous Wave-free Ratio), and discuses the concepts, principals and limitations.

Key learning points:-

• 1. Diastole provides the most sensitive phase of the cardiac cycle to identify stenosis severity
• 2. Pressure is proportional to flow when resistance is stable
• 3. In FFR resistance is stabilised using powerful vasodilator such as adenosine
• 4. In iFR resistance is stabilised by analysing the cardiac cycle over the diastolic Wave-free Period, without the need for drug administration
• 5. Pharmacological hyperaemia differs markedly from exercise induced hyperaemia
• 6. iFR provides a direct measure of the vasodilatory effect on the coronary microcirculation