Instant Wave-Free Ratio or Fractional Flow Reserve for Hemodynamic Coronary Lesion Assessment?
Yes, Just Do It!
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- area under the curve
- coronary artery disease
- myocardial ischemia
- percutaneous coronary intervention
When you come to a fork in the road, take it.
Since the introduction of the instant wave-free ratio (iFR) in 2012,2 the field of coronary physiology has undergone a quantum leap in scientific progress, vigorous debate, and multitude of scientific publications. Although fractional flow reserve (FFR) is based on a plethora of data and well-conduced randomized trials demonstrating substantial clinical benefit,3 its uptake in daily practice has been limited. A potential reason for this may be the somewhat cumbersome technical aspects of the procedure, including the need for hyperemia. Interestingly, although much of the physiological information is present in the resting gradient, the use of that data point has been largely ignored, predominantly because hyperemia was considered a sine qua non for the proper assessment of a coronary stenosis.4
See Article by De Rosa et al
iFR represents a diastolic resting index that allows the assessment of coronary lesions during the phase in the cardiac cycle where microvascular resistance is at its lowest, allowing for increased myocardial perfusion and coronary flow.2 Although microvascular resistance during resting conditions is not as low and coronary flow not as high as during pharmacological hyperemia, iFR may still be sufficient for clinical decision-making under most circumstances. Initial studies comparing iFR against FFR as a reference standard demonstrated good correlation between the 2 indices,2 although subsequent analyses varied with respect to iFR diagnostic accuracy.5 A pooled analysis showed a ≈80% overall diagnostic accuracy of iFR6 which has been widely accepted as an accurate estimate (although the actual correlation can vary based on the patient population studied). The present meta-analysis by De Rosa …