Thresholds of the Invasive Physiological Indices Associated with Anginal Symptoms and an Impaired Exercise Capacity in Patients with Chronic Coronary Syndrome

The Symptom Registry

Abstract

Objective: The thresholds of the fractional flow reserve (FFR) and non-hyperemic pressure ratios (NHPRs) for identifying myocardial ischemia and guiding coronary revascularization are well-established (FFR ≤ 0.80 and NHPRs ≤ 0.89). However, the values associated with patient symptoms remain unclear. This study aimed to identify the thresholds associated with anginal symptoms and an impaired exercise capacity in patients with chronic coronary syndrome (CCS).

Materials and methods: Between July 2022 and January 2025, patients suspected of having CCS and scheduled for coronary angiography were prospectively enrolled at five Japanese institutions. All patients completed a 6-minute walk test (6MWT) and reported the presence or absence of angina symptoms. The exercise capacity was considered impaired if the walking distance was below the predicted value. Subsequently, they underwent angiography with FFR and diastolic pressure ratio (dPR) measurements. A receiver operating characteristic curve analysis was used to determine the thresholds.

Results: Of the 208 enrolled patients, 34 without FFR and dPR measurements were excluded. Anginal symptoms occurred in 40 (23%) patients during the 6MWT, and 39 (22%) had an impaired exercise capacity. The area under the curve for predicting anginal symptoms was 0.68 (95% confidence interval, 0.57–0.78; P < 0.001) for both FFR and dPR measurements. The optimal cutoff values were 0.52 for FFR and 0.60 for dPR, with sensitivities and specificities of 45% and 91%, and 50% and 86%, respectively. In contrast, neither index was associated with an impaired exercise capacity.

Conclusion: The thresholds of FFR and dPR for the occurrence of anginal symptoms were lower than those established for detecting ischemia-inducing lesions and guiding coronary revascularization.