open access
Coronary artery height differences and their effect on fractional flow reserve
Affiliations- Essex Cardiothoracic Centre, Basildon University Hospital, Nethermayne, SS16 5NL Basildon, United Kingdom
- Anglia Ruskin University
- Imperial College Healthcare NHS Trust, London, United Kingdom
open access
Abstract
Background: Fractional flow reserve (FFR) uses pressure-based measurements to assess the severity
of a coronary stenosis. Distal pressure (Pd) is often at a different vertical height to that of the proximal
aortic pressure (Pa). The difference in pressure between Pd and Pa due to hydrostatic pressure, may
impact FFR calculation.
Methods: One hundred computed tomography coronary angiographies were used to measure height
differences between the coronary ostia and points in the coronary tree. Mean heights were used to calculate the hydrostatic pressure effect in each artery, using a correction factor of 0.8 mmHg/cm. This
was tested in a simulation of intermediate coronary stenosis to give the “corrected FFR” (cFFR) and
percentage of values, which crossed a threshold of 0.8.
Results: The mean height from coronary ostium to distal left anterior descending (LAD) was +5.26 cm,
distal circumflex (Cx) –3.35 cm, distal right coronary artery-posterior left ventricular artery (RCA-PLV)
–5.74 cm and distal RCA-posterior descending artery (PDA) +1.83 cm. For LAD, correction resulted in a mean change in FFR of +0.042, –0.027 in the Cx, –0.046 in the PLV and +0.015 in the PDA. Using 200 random FFR values between 0.75 and 0.85, the resulting cFFR crossed the clinical treatment
threshold of 0.8 in 43% of LAD, 27% of Cx, 47% of PLV and 15% of PDA cases.
Conclusions: There are significant vertical height differences between the distal artery (Pd) and its point of normalization (Pa). This is likely to have a modest effect on FFR, and correcting for this results in a proportion of values crossing treatment thresholds. Operators should be mindful of this phenomenon when interpreting FFR values.
Abstract
Background: Fractional flow reserve (FFR) uses pressure-based measurements to assess the severity
of a coronary stenosis. Distal pressure (Pd) is often at a different vertical height to that of the proximal
aortic pressure (Pa). The difference in pressure between Pd and Pa due to hydrostatic pressure, may
impact FFR calculation.
Methods: One hundred computed tomography coronary angiographies were used to measure height
differences between the coronary ostia and points in the coronary tree. Mean heights were used to calculate the hydrostatic pressure effect in each artery, using a correction factor of 0.8 mmHg/cm. This
was tested in a simulation of intermediate coronary stenosis to give the “corrected FFR” (cFFR) and
percentage of values, which crossed a threshold of 0.8.
Results: The mean height from coronary ostium to distal left anterior descending (LAD) was +5.26 cm,
distal circumflex (Cx) –3.35 cm, distal right coronary artery-posterior left ventricular artery (RCA-PLV)
–5.74 cm and distal RCA-posterior descending artery (PDA) +1.83 cm. For LAD, correction resulted in a mean change in FFR of +0.042, –0.027 in the Cx, –0.046 in the PLV and +0.015 in the PDA. Using 200 random FFR values between 0.75 and 0.85, the resulting cFFR crossed the clinical treatment
threshold of 0.8 in 43% of LAD, 27% of Cx, 47% of PLV and 15% of PDA cases.
Conclusions: There are significant vertical height differences between the distal artery (Pd) and its point of normalization (Pa). This is likely to have a modest effect on FFR, and correcting for this results in a proportion of values crossing treatment thresholds. Operators should be mindful of this phenomenon when interpreting FFR values.
Keywords
hydrostatic pressure, computed tomography coronary angiography, coronary stenosis
About this articleTitle
Coronary artery height differences and their effect on fractional flow reserve
Journal
Issue
Article type
Original Article
Pages
41-48
Published online
2019-03-14
Page views
1531
Article views/downloads
1448
DOI
10.5603/CJ.a2019.0031
Pubmed
Bibliographic record
Cardiol J 2021;28(1):41-48.
Keywords
hydrostatic pressure
computed tomography coronary angiography
coronary stenosis
Authors
Firas Al-Janabi
Grigoris Karamasis
Chritopher M. Cook
Alamgir M. Kabir
Rohan O. Jagathesan
Nicholas M. Robinson
Jeremy W. Sayer
Rajesh K. Aggarwal
Gerald J. Clesham
Paul R. Kelly
Reto A. Gamma
Kare H. Tang
Thomas R. Keeble
John R. Davies
References (15)- Zimmermann FM, Ferrara A, Johnson NP, et al. Deferral vs. performance of percutaneous coronary intervention of functionally non-significant coronary stenosis: 15-year follow-up of the DEFER trial. Eur Heart J. 2015; 36(45): 3182–3188.
- Pijls NHJ, Fearon WF, Tonino PAL, et al. Fractional flow reserve versus angiography for guiding percutaneous coronary intervention in patients with multivessel coronary artery disease: 2-year follow-up of the FAME (Fractional Flow Reserve Versus Angiography for Multivessel Evaluation) study. J Am Coll Cardiol. 2010; 56(3): 177–184.
- Xaplanteris P, Fournier S, Pijls NHJ, et al. Five-Year outcomes with PCI guided by fractional flow reserve. N Engl J Med. 2018; 379(3): 250–259.
- Davies JE, Sen S, Dehbi H-M, et al. Use of the Instantaneous Wave-free Ratio or Fractional Flow Reserve in PCI. N Engl J Med. 2017; 376(19): 1824–1834.
- Tebaldi M, Biscaglia S, Fineschi M, et al. Evolving Routine Standards in Invasive Hemodynamic Assessment of Coronary Stenosis: The Nationwide Italian SICI-GISE Cross-Sectional ERIS Study. JACC Cardiovasc Interv. 2018; 11(15): 1482–1491.
- Nijjer SS, de Waard GA, Sen S, et al. Coronary pressure and flow relationships in humans: phasic analysis of normal and pathological vessels and the implications for stenosis assessment: a report from the Iberian-Dutch-English (IDEAL) collaborators. Eur Heart J. 2016; 37(26): 2069–2080.
- Härle T, Luz M, Meyer S, et al. Effect of coronary anatomy and hydrostatic pressure on intracoronary indices of stenosis severity. JACC Cardiovasc Interv. 2017; 10(8): 764–773.
- Davies JE, Whinnett ZI, Francis DP, et al. Evidence of a dominant backward-propagating "suction" wave responsible for diastolic coronary filling in humans, attenuated in left ventricular hypertrophy. Circulation. 2006; 113(14): 1768–1778.
- Kobayashi N, Maehara A, Brener SJ, et al. Usefulness of the Left Anterior Descending Coronary Artery Wrapping Around the Left Ventricular Apex to Predict Adverse Clinical Outcomes in Patients With Anterior Wall ST-Segment Elevation Myocardial Infarction (from the Harmonizing Outcomes With Revascularization and Stents in Acute Myocardial Infarction Trial). Am J Cardiol. 2015; 116(11): 1658–1665.
- Härle T, Meyer S, Bojara W, et al. Intracoronary pressure measurement differences between anterior and posterior coronary territories. Herz. 2017; 42(4): 395–402.
- Petraco R, Escaned J, Sen S, et al. Classification performance of instantaneous wave-free ratio (iFR) and fractional flow reserve in a clinical population of intermediate coronary stenoses: results of the ADVISE registry. EuroIntervention. 2013; 9(1): 91–101.
- Härle T, Luz M, Meyer S, et al. Influence of hydrostatic pressure on intracoronary indices of stenosis severity in vivo. Clin Res Cardiol. 2018; 107(3): 222–232.
- De Bruyne B, Hersbach F, Pijls NH, et al. Abnormal epicardial coronary resistance in patients with diffuse atherosclerosis but "Normal" coronary angiography. Circulation. 2001; 104(20): 2401–2406.
- Tebaldi M, Biscaglia S, Fineschi M, et al. Fractional flow reserve evaluation and chronic kidney disease: analysis from a multicenter italian registry (the FREAK study). Catheter Cardiovasc Interv. 2016; 88(4): 555–562.
- Ramanathan T, Skinner H. Coronary blood flow. Contin Educ Anaesth Crit Care Pain. 2005; 5(2): 61–64.
