The impact of downstream coronary stenoses on fractional flow reserve assessment of intermediate left main disease.
OBJECTIVE
The aim of this study was to assess the validity of measuring fractional flow reserve (FFR) of the left main (LM) coronary artery in the setting of concomitant left anterior descending (LAD) or left circumflex (LCX) stenoses.


BACKGROUND
The theoretical impact of a stenosis in the LAD on the FFR assessment of intermediate LM disease with the pressure wire in an unobstructed LCX is currently unknown.


METHODS
A previously validated in vitro model of the coronary circulation was used to create a fixed intermediate stenosis of the LM and a variable downstream LAD or LCX stenosis. The true LM FFR (FFR(LM true)), with no concomitant downstream disease, was compared to the apparent LM FFR (FFR(LM apparent)), with concomitant downstream disease measured with different degrees of LAD or LCX disease. Additionally, an equation based on a resistors model was derived to predict the effect of downstream stenosis on LM FFR (FFR(LM predicted)).


RESULTS
In the setting of isolated moderate LM disease (FFR 0.72 ± 0.08), mild to moderate proximal LAD or LCX lesions did not significantly affect LM FFR. Lesions with a composite FFR (LM + downstream disease) ≥0.65 resulted in an FFR(LM apparent) that was not significantly different from FFR(LM true) (0.76 ± 0.06 vs. 0.76 ± 0.05, p = 0.124). Our equation for FFR(LM predicted) accurately modeled the effects of concomitant disease (r = 0.95, p < 0.001).


CONCLUSIONS
These data suggest that in the presence of proximal mild to moderate LAD or LCX disease, LM FFR can be reliably measured with the pressure wire placed in the uninvolved epicardial artery.
Stanford University Medical Center, Stanford, CA 94305, USA.
David V
DV
Daniels
Marcel
M
van't Veer
Nico H J
NH
Pijls
Arjen
A
van der Horst
Andy S
AS
Yong
Bernard
B
De Bruyne
William F
WF
Fearon
D003324:Coronary Artery Disease / Q000473:pathology*; D023903:Coronary Restenosis / Q000473:pathology*; D003331:Coronary Vessels / Q000473:pathology*; D018450:Disease Progression; D053805:Fractional Flow Reserve, Myocardial; D006801:Humans; D008962:Models, Theoretical; D011379:Prognosis; D015203:Reproducibility of Results; D012720:Severity of Illness Index