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Published on: April 13, 2015
Agreement of the Resting Distal to Aortic Coronary Pressure With the Instantaneous Wave-Free Ratio
Yuhei Kobayashi1, Nils P Johnson2, Frederik M Zimmermann3
1Stanford University School of Medicine, Stanford, California; Stanford Cardiovascular Institute, Stanford, California.
Insights
The resting distal to aortic coronary pressure (Pd/Pa) shows excellent agreement with the instantaneous wave-free ratio (iFR), suggesting Pd/Pa is a reliable index for guiding revascularization in patients with coronary artery disease.
Area of Science:
- Cardiology
- Interventional Cardiology
- Physiological measurements
Background:
- Recent trials show instantaneous wave-free ratio (iFR) noninferior to fractional flow reserve for revascularization guidance.
- Resting distal to aortic coronary pressure (Pd/Pa) is an available adenosine-free index, but its agreement with iFR is unknown.
Purpose of the Study:
- To investigate the agreement between Pd/Pa and iFR in patients undergoing coronary physiological assessment.
Main Methods:
- Prospective enrollment of 763 patients across 12 institutions.
- Simultaneous measurement of iFR and Pd/Pa under resting conditions.
- Assessment of Pd/Pa agreement with iFR (≤0.89) and determination of optimal cutoff value.
Main Results:
- Pd/Pa was analyzable in more patients (96.1%) than iFR (82.2%).
- High correlation (R²=0.93) and excellent agreement (AUC=0.98) between Pd/Pa and iFR were observed.
- Optimal Pd/Pa cutoff was ≤0.91, with high diagnostic accuracy (93.0%).
Conclusions:
- Pd/Pa is more frequently analyzable than iFR.
- Pd/Pa demonstrates excellent agreement with iFR, supporting its clinical utility.
- Findings were consistent across patients with acute coronary syndrome and stable angina.
Background:
Recently, 2 randomized controlled trials showed that the instantaneous wave-free ratio (iFR), a resting coronary physiological index, is noninferior to fractional flow reserve for guiding revascularization. The resting distal to aortic coronary pressure (Pd/Pa) measured at rest is another adenosine-free index widely available in the cardiac catheterization laboratory; however, little is known about the agreement of Pd/Pa using iFR as a reference standard.
Objectives:
The goal of this study was to investigate the agreement of Pd/Pa with iFR.
Methods:
A total of 763 patients were prospectively enrolled from 12 institutions. iFR and Pd/Pa were measured under resting conditions. Using iFR ≤0.89 as a reference standard, the agreement of Pd/Pa and its best cutoff value were assessed.
Results:
According to the independent core laboratory analysis, iFR and Pd/Pa were analyzable in 627 and 733 patients (82.2% vs. 96.1%; p < 0.001), respectively. The median iFR and Pd/Pa were 0.90 (interquartile range: 0.85 to 0.94) and 0.92 (interquartile range: 0.88 to 0.95), and the 2 indices were highly correlated (R2 = 0.93; p < 0.001; iFR = 1.31 * Pd/Pa -0.31). According to the receiver-operating characteristic curve analysis, Pd/Pa showed excellent agreement (area under the curve: 0.98; 95% confidence interval: 0.97 to 0.99; p < 0.001) with a best cutoff value of Pd/Pa ≤0.91. The diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value were 93.0%, 91.4%, 94.4%, 93.3%, and 92.7%, respectively. These results were similar in patients with acute coronary syndrome and stable angina.
Conclusions:
Pd/Pa was analyzable in a significantly higher number of patients than iFR. Pd/Pa showed excellent agreement with iFR, suggesting that it could be applied clinically in a similar fashion. (Can Contrast Injection Better Approximate FFR Compared to Pure Resting Physiology? [CONTRAST]; NCT02184117).
