Impact of right atrial pressure on fractional flow reserve calculation in the presence of a chronic total occlusion.

BACKGROUND

The aim of this study was to assess the impact of right atrial pressure (Pra) on non-CTO vessels FFR measurements in patients with a chronic total occlusion.

METHODS

Consecutive patients who underwent PCI for a CTO of the right coronary artery (RCA) were included. Prior to RCA recanalization, FFR and FFRmyo were measured in non-CTO vessels. FFR was calculated using the Pd/Pa equation during maximum hyperaemia and also accounting for right atrial pressure (Pd-Pra/Pa-Pra). Non-CTO vessels were characterised as major or minor donors based on angiographic assessment of provided collaterals.

RESULTS

FFR and FFRmyo were measured in 68 arteries (34 LAD and 34 Cx) in 34 consecutive patients with successful RCA CTO PCI. Patients' mean age was 62 ± 10 years old and 88% were male. Mean left ventricular ejection fraction was 51% ± 20. During maximum hyperaemia, mean Pra, Pa, and Pd were 4.1 ± 3.8 mm Hg, 82.6 ± 12.2 mm Hg, and 63.8 ± 14.3 mm Hg, respectively. In the major donor vessel, FFRmyo showed a difference of 0.007 to FFR (0.760 ± 0.113 vs. 0.767 ± 0.112, p = 0.004). In the minor donor vessel the difference was 0.004 (0.895 ± 0.067 vs. 0.899 ± 0.065, p < 0.001). There was a strong positive correlation between the FFR and FFRmyo in both the major and minor donor vessel groups (r = 0.993, p < 0.001 and r = 0.996, p < 0.001 respectively).

CONCLUSION

In the presence of a CTO, RA pressure adjustment of FFR in the non-CTO vessels leads to trivial numerical changes, which are statistically significant but clinically negligible.