Disturbed coronary hemodynamics in vessels with intermediate stenoses evaluated with fractional flow reserve: a...

Area of Science:

• Cardiovascular Medicine
• Interventional Cardiology
• Physiology

Background:

• Chronic ischemic heart disease involves focal stenosis, diffuse atherosclerosis, and microcirculatory dysfunction (MCD), limiting myocardial blood flow.
• The prevalence of these conditions in vessels assessed by fractional flow reserve (FFR) is not well understood.

Purpose of the Study:

• To investigate the prevalence and patterns of hemodynamic disturbances in coronary arteries with intermediate stenoses.
• To explore the relationship between FFR, coronary flow reserve (CFR), and index of microcirculatory resistance (IMR) in defining ischemic heart disease.

Main Methods:

• Intracoronary measurements were used in 91 coronary arteries from 78 patients with intermediate stenoses.
• Vessels were classified into four groups based on FFR (>0.80) and CFR (<2) values.
• Index of microcirculatory resistance (IMR) and Gensini score (atherosclerotic burden) were assessed; MCD was defined as IMR ≥29.1.

Main Results:

• 59.3% of vessels had normal FFR (>0.80), but only 37% of these also had normal CFR and IMR.
• Among vessels with FFR >0.80, 63% exhibited disturbed hemodynamics, with abnormal CFR in 52% and MCD in 33%.
• Vessels with FFR >0.80 showed significantly higher IMR compared to those with FFR ≤0.80 (27.6 vs 17.3, p=0.001).
• Atherosclerotic burden correlated inversely with CFR (r=-0.207, P=0.055).
• Vessels with FFR >0.80 and CFR <2 displayed a wide range of IMR, suggesting combined diffuse atherosclerosis and MCD.

Conclusions:

• A significant proportion of coronary arteries with intermediate stenoses (FFR >0.80) exhibit abnormal hemodynamics.
• Integrating FFR, CFR, and IMR helps differentiate patterns of ischemic heart disease, including combinations of focal/diffuse stenosis and varying degrees of MCD.