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Abnormal epicardial coronary resistance in patients with diffuse atherosclerosis but "Normal" coronary angiography
B De Bruyne1, F Hersbach, N H Pijls
1Cardiovascular Center Aalst, Aalst, Belgium. bernard.de.bruyne@olvz-aalst.be
Insights
Diffuse coronary atherosclerosis, even without visible blockages, reduces blood flow and pressure in coronary arteries. This finding impacts understanding of myocardial ischemia and treatment decisions.
Area of Science:
- Cardiovascular Medicine
- Interventional Cardiology
- Physiology
Background:
- Angiography often misses diffuse coronary atherosclerosis, a common process in coronary artery disease.
- Non-obstructive coronary arteries are typically considered to have normal flow dynamics.
- Atherosclerosis is a diffuse disease affecting the entire arterial length, not just focal stenoses.
Purpose of the Study:
- To investigate if non-stenotic coronary arteries in patients with coronary artery disease exhibit reduced pressure and flow.
- To quantify the pressure drop across non-obstructive coronary segments due to diffuse atherosclerosis.
- To determine the impact of diffuse atherosclerosis on coronary conductance and fractional flow reserve (FFR).
Main Methods:
- Measurement of coronary pressure and fractional flow reserve (FFR) in non-stenotic arteries.
- Comparison between healthy individuals (Group I) and patients with coronary artery disease (Group II).
- Analysis of pressure gradients at rest and during hyperemia to assess coronary resistance.
Main Results:
- Non-stenotic arteries in patients with coronary artery disease showed significantly higher pressure gradients compared to healthy controls.
- Fractional flow reserve (FFR) was significantly lower in non-stenotic arteries of patients with coronary artery disease, indicating increased resistance.
- A substantial percentage of non-stenotic arteries exhibited FFR values below normal, with some reaching the threshold for inducible ischemia.
Conclusions:
- Diffuse coronary atherosclerosis without focal stenosis causes a continuous pressure reduction along the coronary artery length.
- This continuous pressure fall contributes to myocardial ischemia.
- The presence of diffuse atherosclerosis in non-stenotic segments has implications for interventional cardiology decision-making.
Background:
Coronary arteries without focal stenosis at angiography are generally considered non-flow-limiting. However, atherosclerosis is a diffuse process that often remains invisible at angiography. Accordingly, we hypothesized that in patients with coronary artery disease, nonstenotic coronary arteries induce a decrease in pressure along their length due to diffuse coronary atherosclerosis.
Methods And Results:
Coronary pressure and fractional flow reserve (FFR), as indices of coronary conductance, were obtained from 37 arteries in 10 individuals without atherosclerosis (group I) and from 106 nonstenotic arteries in 62 patients with arteriographic stenoses in another coronary artery (group II). In group I, the pressure gradient between aorta and distal coronary artery was minimal at rest (1+/-1 mm Hg) and during maximal hyperemia (3+/-3 mm Hg). Corresponding values were significantly larger in group II (5+/-4 mm Hg and 10+/-8 mm Hg, respectively; both P<0.001). The FFR was near unity (0.97+/-0.02; range, 0.92 to 1) in group I, indicating no resistance to flow in truly normal coronary arteries, but it was significantly lower (0.89+/-0.08; range, 0.69 to 1) in group II, indicating a higher resistance to flow. In 57% of arteries in group II, FFR was lower than the lowest value in group I. In 8% of arteries in group II, FFR was <0.75, the threshold for inducible ischemia.
Conclusion:
Diffuse coronary atherosclerosis without focal stenosis at angiography causes a graded, continuous pressure fall along arterial length. This resistance to flow contributes to myocardial ischemia and has consequences for decision-making during percutaneous coronary interventions.
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