Impact of right atrial pressure on decision-making using fractional flow reserve (FFR) in elective percutaneous intervention.

Background: We undertook a prospective study to assess the impact of routine incorporation of right atrial pressure into the calculation of FFR in a real world elective PCI cohort.

Methods: 42 patients with stenoses in 2 separate epicardial vessels at coronary angiography were studied. Using a temperature and pressure sensing guidewire (TPSG) FFR and FFRRAP were performed in the target vessel pre and post PCI and in a non-target vessel. FFR was defined as Pd/Pa, FFRRAP as Pd-Pv/Pa-Pv where Pv was right atrial pressure and Pd/Pa were the hyperemic distal and proximal arterial pressures respectively.

Results: Mean RAP was 9.1 ± 0.7 mmHg. Mean FFR was significantly lower when RAP was included in the calculation (FFRRAP 0.77 ± 0.19 vs. FFR 0.80 ± 0.16, p<0.001). In the target vessel pre PCI, incorporating RAP into the calculation of FFR resulted in a significant difference in the FFR value (FFR Pre-PCI 0.69 ± 0.02 vs. FFRRAP Pre-PCI 0.63 ± 0.03, p<0.0001). 21 patients had an FFR ≤ 0.8 in the group. If right atrial pressure were utilized to calculate FFR prior to PCI, an additional 9 patients would have been re-categorised to an FFR ≤ 0.8. Following PCI, mean FFR was lower when RAP was incorporated (Post PCI FFRRAP 0.93±0.05 vs. Post PCI FFR 0.95 ± 0.06, p<0.001).

Conclusion: Incorporation of right atrial pressure into the calculation of FFR significantly alters FFR values and may potentially reclassify lesions below ischaemic thresholds.