iFR

Instantaneous wave-free ratio (iFR) is haemodynamic resting index for assessment of coronary artery stenosis severity. iFR uses high frequency sampling to calculate a gradient across a coronary lesion during a period of diastole – the “wave-free period”.

The new guidelines have provided the highest recommendation for iFR alongside fractional flow reserve (FFR) for the objective assessment of the hemodynamic relevance of coronary lesions. In 2017, the DEFINE-FLAIR and iFR Swedeheart studies, the largest randomised coronary physiology outcome studies published to date, showed iFR to be a non-inferior method to FFR during risk stratification in coronary stenosis.