Use of resting non-hyperemic indices for avoidance of fractional flow reserve measurement: The goal of 100% accuracy


Aurora Cardiovascular Services, Aurora St. Luke's Medical Center


OBJECTIVES: Recent studies have suggested that fractional flow reserve (FFR) measurement can be avoided by using similar ranges of baseline mean coronary pressure (Pd) to mean aortic pressure (Pa) ratio (0.88-0.95). Further studies have suggested that too many significant coronary stenoses are misclassified based on these ranges. We hypothesized that with a certain range of baseline Pd/Pa, 100% positive predictive value (PPV) and negative predictive value (NPV) can be achieved to avoid misclassification.

METHODS: We retrospectively evaluated the pressure tracings of 555 consecutive intermediate coronary stenotic lesions that had undergone FFR measurement in the cardiac catheterization laboratory of a tertiary-care center. The baseline Pd/Pa was manually measured and correlated with final FFR. The operating test characteristics were calculated using an abnormal FFR of ≤0.80 as the criterion standard for the presence of hemodynamic, significant coronary stenosis.

RESULTS: The area under the receiver-operating characteristics curve of baseline Pd/Pa for predicting FFR was 0.89, very similar to published results for instantaneous wave-free ratio and Pd/Pa. However, a significant number of lesions were mischaracterized (ie, using a baseline Pd/Pa of ≤0.88 to >0.95, there were 22 misclassifications, with 6 false-positive and 16 false-negative results). At a Pd/Pa of ≤0.86, 100% PPV was achieved, and 100% NPV was achieved at >1.00.

CONCLUSION: A baseline Pd/Pa of ≤0.86 is associated with a PPV of 100%, which can avoid the misclassification errors seen in prior studies. This provides a more clinically useful application of baseline Pd/Pa.

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