Abstract
The effect of hydrostatic pressure on physiological intracoronary measurements is usually ignored in the daily clinical practice. Our aim was to investigate this effect on Pd/Pa (distal/aortic pressure) and FFR (fractional flow reserve). 41 FFR measurements between 0.7 and 0.9 were selected. The difference in the height of the orifice and that of the sensor was defined in mm on the basis of 3D coronary reconstruction. Resting Pd/Pa and FFR were adjusted by subtracting the hydrostatic pressure gradient from the distal pressure. Height measurements were also performed from 2D lateral projections for each coronary segment (n = 305). In case of the LAD, each segment was located higher (proximal: − 13.69 ± 5.4; mid: − 46.13 ± 6.1; distal: − 56.80 ± 7.7 mm), whereas for the CX, each segment was lower (proximal: 14.98 ± 8.3; distal: 28.04 ± 6.3 mm) compared to the orifice. In case of the RCA, the distances from the orifice were much less (proximal: − 6.39 ± 2.9; mid: − 6.86 ± 7.0; distal: 17.95 ± 6.6 mm). The effect of these distances on pressure ratios at 100 Hgmm aortic pressure was between − 0.044 and 0.023. The correction for height differences changed the interpretation of the measurement (negative/positive result) in 5 (12%) and 11 (27%) cases for the FFR (cut-off value at 0.80) and the resting Pd/Pa (cut-off value at 0.92), respectively. The clinical implementation of hydrostatic pressure calculation should be considered during intracoronary pressure measurements. A correction for this parameter may become crucial in case of a borderline significant coronary artery stenosis, especially in distal coronary artery segments.
Highlights
Fractional flow reserve (FFR) and non‐hyperemic pressure ratio (NHPR) measurementsAccording to current guidelines, the physiological measurement of coronary artery stenoses is recommended in chronic coronary syndrome
Our aim was to investigate the effect of resting Pd/Pa and FFR adjustment based on the calculation of hydrostatic pressure gradient between the coronary orifice and the pressure wire sensor, to identify the relevance of hydrostatic pressure during clinical decision making, in cases where FFR values were near the cut-off
Given the dichotomous interpretation of stenosis severity by the FFR measurement, we found a similar rate in the change of classification of an intermediate severity coronary artery stenosis after adjusting for hydrostatic pressure as in previous publications [15,16,17,18]
Summary
Fractional flow reserve (FFR) and non‐hyperemic pressure ratio (NHPR) measurements. The physiological measurement of coronary artery stenoses is recommended in chronic coronary syndrome. FFR is considered to be a standard method for the evaluation of myocardial ischemia and the likely advantage of revascularization [1,2,3,4,5,6,7]. FFR is calculated as the ratio of distal coronary artery pressure (Pd) and aortic pressure (Pa) during maximal hyperemia, usually induced by intracoronary or intravenous adenosine [8]. The accuracy of physiological intracoronary measurements is influenced by several factors. Pitfalls may originate from the preparation (calibration, equalization) or from the measurement itself (submaximal hyperemia, drifting, whipping, wedging).
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