The following is the summary of “Relation Between Coronary Plaque Composition Assessed by Intravascular Ultrasound Virtual Histology and Myocardial Ischemia Assessed by Quantitative Flow Ratio,” published in the January 2023 issue of Cardiovascular Disease by Smit et al.
Myocardial ischemia may be induced in part by the makeup of coronary plaques. Our primary focus was to understand better how coronary plaque composition relates to myocardial ischemia in patients experiencing chest discomfort. A total of 103 people who complained of chest pain were referred for diagnostic invasive coronary angiography after visiting an outpatient clinic or the emergency room. Assessment of coronary plaque composition was performed by intravascular ultrasound virtual histology.
A necrotic core and fibrofatty tissue made up what was called a noncalcified plaque. The gold standard for assessing myocardial ischemia was quantitative flow ratio (QFR), a coronary angiography-based technique that can quantify fractional flow reserve without inducing hyperemia or using a pressure wire. Plaques in the coronary arteries were regarded as abnormal if their QFR was less than ≤0.80, indicating they could cause ischemia. Of 149 coronary plaques examined, 21 were deemed anomalous (14%). Plaques with aberrant QFR had a larger percentage of noncalcified tissue than normal (38.2± 6.5% vs. 33.1 ±9.0%, P=0.014).
In univariate analysis, an increase in either plaque burden (odds ratio [OR] per 1% increase 1.081, P<0.001) or the proportion of noncalcified tissue (OR per 1% increase 1.070, P=0.020) was linked with a decrease in QFR. Multivariate analysis, however, revealed that only plaque load was independently linked to aberrant QFR (OR per 1% increase 1.072, P<0.001). In conclusion, the extent of noncalcified plaque was substantially greater in hemodynamically important coronary lesions than in nonsignificant lesions. When adjusted for regional plaque load, a significant correlation between increasing noncalcified plaque area and decreased QFR was no longer present.