Influence of arterial hypotension on fractional flow reserve measurements

AIMS: To assess fractional flow reserve (FFR) variability in case of arterial hypotension in the clinical setting. FFR measurement is supposed to be independent of haemodynamics; there is, however, a strong relationship between trans-stenotic pressure variation and coronary flow. Non-clinical models suggest an inverse relationship between arterial pressure and FFR, but no clinical data have as yet confirmed this hypothesis. METHODS AND RESULTS: In case of arterial hypotension (mean arterial pressure [Pa] \textless/=80 mmHg) during routine clinical FFR measurement (FFR1), a second measurement (FFR2) was performed after pressure normalisation by 0.5 mg IV phenylephrine. Fourteen intermediate chronic stenoses (%DS 58+/-21%, FFR1= 0.81+/-11) in 12 male patients showed 70+/-10 mmHg Pa at the time of measurement. After phenylephrine, Pa increased to 101+/-14 mmHg and FFR2 decreased to 0.75+/-12 (p\textless0.001) without heart rate variation. After Pa elevation, 40% of cases with FFR1 \textgreater0.80 changed to FFR2 \textless/=0.80. CONCLUSIONS: In the present study, in case of arterial hypotension, FFR decreased with rising pressure. Whether repeated FFR measurement after haemodynamic normalisation is of clinical benefit remains at this point speculative and should be validated in a larger data set.