Physiological thresholds associated with angina symptoms varied substantially according to cardiac workload and were consistently lower than standard ischemia-based revascularization thresholds, according to findings from the ORBITA-FIRE trial.

The study published in the Circulation included 65 patients with a mean age of 63.9±8.7 years; 74% were men, 69% had hypertension, 23% had diabetes, and 91% had Canadian Cardiovascular Society class II–III angina. Median pre-PCI FFR was 0.59 (interquartile range [IQR] 0.46–0.70), while median RFR was 0.61 (IQR 0.40–0.82).

Median FFRangina increased from 0.29 (IQR 0.23–0.35) at rest to 0.38 (IQR 0.30–0.48) during low-intensity exercise and 0.45 (IQR 0.36–0.55) during high-intensity exercise. Similarly, median RFRangina increased from 0.22 (IQR 0.16–0.30) at rest to 0.26 (IQR 0.18–0.36) and 0.32 (IQR 0.23–0.46) during low- and high-intensity exercise, respectively. All thresholds remained significantly below conventional diagnostic cut points (P<0.001).

Lower FFRangina and RFRangina thresholds were associated with greater reproducibility of symptoms across exercise conditions and predicted higher baseline angina burden and greater symptomatic improvement following PCI.

The findings suggest that angina-related physiological thresholds are individualized and workload dependent, supporting a more symptom-focused physiological approach to patient selection for PCI.