Resting Non-hyperemic Indices and the Goal of 100% Accuracy

By Khawaja Afzal Ammar, MD

We all use fractional flow reserve (FFR) in evaluating intermediate lesions in coronary arteries. This increases the procedure time, but it also increases the probability of appropriate interventions that will actually help the patients with their symptoms. In order to decrease procedure time, resting non-hyperemic indices such as instantaneous wave-free ratio (iFR) and the ratio of coronary pressure to aortic pressure (Pd/Pa) prior to infusion of adenosine have been promoted. In an article published in this month’s Journal of Invasive Cardiology, we looked at almost 1000 FFR measurements made in our practice and discovered that if we use a Pd/Pa of <0.87 as indicative of an FFR of <0.8, then the positive predictive value is 100% with a 0% error rate. Other classification guidelines, whether using iFr or Pd/Pa of 0.88 to 0.93, result in too many classification errors and a much lower positive predictive value than 100%. Since FFR measurement after adenosine infusion does not add more than 5 to 8 minutes in the cath lab, we should not settle for anything less than 100% accuracy, 100% positive predictive value, and 0% misclassification rate.

Read the entire article in this month’s JIC:
Use of Resting Non-hyperemic Indices for Avoidance of Fractional Flow Reserve Measurement: The Goal of 100% Accuracy.
Khawaja Afzal Ammar, MD;  Syed Shahab Kazmi, MBBS;  Mirza Nubair Ahmad, MBBS;  Mirza Mujadil Ahmad, MBBS;  Arsalan Riaz, MBBS;  Imran Husain, BS;  Fatima Husain, MBBS;  Suhail Allaqaband, MD;  Tanvir Bajwa, MD;  Anjan Gupta, MD
J INVASIVE CARDIOL 2016;28(7):265-270

Read the accompanying commentary:

No Stenosis Left Behind – The Holy Grail of 100% Predictive Accuracy

James R. Wilentz, MD

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