Heparin infusion after successful coronary intervention is associated with more minor bleeding and vascular injury, prolonged length of stay and increased cost. In-hospital and one-month ischemic events rarely occur after successful intervention, irrespective of heparin use. Routine postprocedure heparin is not recommended, even in patients who present with unstable ischemic syndromes.
Background:
Invasive fractional flow reserve (FFR
INV
) is the standard technique for assessing myocardial ischemia. Pressure distortions and measurement location may influence FFR
INV
interpretation. We report a technique for performing invasive fractional flow reserve (FFR
INV
) by minimizing pressure distortions and identifying the proper location to measure FFR
INV
.
Methods:
FFR
INV
recordings were obtained prospectively during manual hyperemic pullback in 100 normal and diseased coronary arteries with single stenosis, using 4 measurements from the terminal vessel, distal-to-the-lesion, proximal vessel, and guiding catheter. FFR
INV
profiles were developed by plotting FFR
INV
values (
y
-axis) and site of measurement (
x
-axis), stratified by stenosis severity. FFR
INV
≤0.8 was considered positive for lesion-specific ischemia.
Results:
Erroneous FFR
INV
values were observed in 10% of vessels because of aortic pressure distortion and in 21% because of distal pressure drift; these were corrected by disengagement of the guiding catheter and re-equalization of distal pressure/aortic pressure, respectively. There were significant declines in FFR
INV
from the proximal to the terminal vessel in normal and stenotic coronary arteries (
P
<0.001). The rate of positive FFR
INV
was 41% when measured from the terminal vessel and 20% when measured distal-to-the-lesion (
P
<0.001); 41.5% of positive terminal measurements were reclassified to negative when measured distal-to-the-lesion. Measuring FFR
INV
20 to 30 mm distal-to-the-lesion (rather than from the terminal vessel) can reduce errors in measurement and optimize the assessment of lesion-specific ischemia.
Conclusions:
Meticulous technique (disengagement of the guiding catheter, FFR
INV
pullback) is required to avoid erroneous FFR
INV
, which occur in 31% of vessels. Even with optimal technique, FFR
INV
values are influenced by stenosis severity and the site of pressure measurement. FFR
INV
values from the terminal vessel may overestimate lesion-specific ischemia, leading to unnecessary revascularization.
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