The Relationship Between Intravascular Ultrasound-derived Percent Total Atheroma Volume and Fractional Flow Reserve in the Intermediate Stenosis of Proximal or Middle Left Anterior Descending Coronary Artery

Background: It remains undefined whether the atherosclerotic disease extent of the conductive vessel (expressed as intravascular ultrasound [IVUS]-derived percent total atheroma volume [%TAV]), correlates with functional severity of intermediate stenosis of left anterior descending artery (LAD).

Methods: An IVUS study and fractional flow reserve (FFR) measurements performed in 130 patients with coronary angiographic intermediate stenosis of proximal or middle LAD. %TAV was calculated as the percentage of total vessel volume occupied by total atheroma volume on IVUS.

Results: A significant correlation was observed between %TAV and FFR (r=-0.71, p<0.001). Minimal lumen area (MLA) correlated moderately with FFR (r=0.54, p<0.001). The independent predictors of FFR<0.8 were %TAV (odds ratio [OR]: 1.29, 95% confidence interval [CI]=1.18-1.40, p<0.001) and MLA (OR: 0.37, 95% CI=0.16-0.85, p=0.019). A receiver-operating characteristic curve suggested %TAV ≥ 39.0% (sensitivity 85%, specificity 83% and area under curve [AUC]=0.90) and MLA ≤ 2.6mm(2) (sensitivity 72%, specificity 70% and AUC=0.75) as the best cut-off values for FFR<0.8. Forty-eight point five (48.5%) of total studied lesions (63/130) showed %TAV ≥ 39.0%. Eighty-four point four (84.4%) of lesions (38/45) with %TAV ≥ 39.0% and MLA ≤ 2.6mm(2), and 72.2% of lesions (13/18) with %TAV ≥ 39.0% and MLA>2.6mm(2), FFR was less than 0.8.

Conclusions: Volumetric quantification of the atherosclerotic disease extent of the coronary artery, expressed as IVUS-derived %TAV, showed a strong correlation with FFR. Not only the segmental luminal narrowing but also the total plaque burden of conductive artery are major determinants for the presence of myocardial ischemia in intermediate stenosis of LAD.