The Impact of Plaque Rupture on Mismatch Between Intravascular Ultrasound Minimal Lumen Area and Fractional Flow Reserve Measured in an Angiographically Borderline Left Main With Complex Left Anterior Descending Involvement

J INVASIVE CARDIOL 2019;31(4):E60-E61.

Key words: anatomy-functional mismatch, fractional flow reserve, intravascular ultrasound

Coronary angiography was performed in a 63-year-old woman due to symptoms of angina pectoris (Canadian Cardiovascular Society class 3), revealing a 50% stenosis of the left main (LM) coronary artery located before its bifurcation, irregular narrowing of the left anterior descending (LAD) coronary artery ostium and its proximal segment (Figures 1 and 2; arrows), and borderline (40%-70%) stenosis along the entire mid LAD (Figure 3). Minimal fractional flow reserve (FFR) measured in the distal LAD was 0.76 (Figure I), justifying angioplasty, but it was of limited usefulness in planning the intervention in the setting of multiple complex lesions, one of which involved the LM.

Treatment planning was supported by the tomographic perspective of intravascular ultrasound (IVUS), which showed a proximal LM reference lumen area of 13.6 mm² with a plaque burden <30% (Figure A), a borderline minimal lumen area in the LM of 6.2 mm² with full circumference of superficial calcium (Figure B), extensive plaque burden at the LAD ostium with a lumen area of 7.8 mm² (Figure C), and plaque rupture, corresponding with the angiographically complex LAD lesion (Figures D-F; arrows indicate the rupture cavity) where the lumen area measured 4.5 mm² (importantly not including the rupture cavity) followed by a long segment in the mid LAD containing the minimal lumen area of 3.0 mm².

Considering that plaque rupture is known to affect the mismatch between anatomy and physiology, we relied on FFR and implanted the first drug-eluting stent (DES) at the site of the most narrowed mid LAD (Figure 3-a). FFR was repeated, and its value fell to 0.69, reflecting the increased hyperemic flow and pressure drop across the remaining lesion(s) that occurred after stenting the most anatomically severe stenosis (Figure II). Thus, the second DES was implanted proximal to the first stent (Figure 3-b), after which the minimum FFR still measured 0.75 (Figure III).

Finally, we decided to implant the third DES from the proximal LM across the left circumflex artery, covering the LAD ostium and proximal segments (Figures 4 and 5). All stent margins were overlapping, and postdilated with a 3.5 mm non-compliant balloon at 20 atm (Figure 6). Finally, minimal in-stent cross-sectional areas were >9.0 mm², minimum FFR was 0.88 (Figure IV), and the absence of drift was documented on FFR wire pull-back. The phenomenon of the significant decrease of a minimal FFR value due to the presence of a plaque rupture, being independent of the respective minimal cross-sectional lumen area, was proved in the large-scale IVUS studies (the so called visual-functional mismatch or anatomy-functional mismatch).

From ¹Medical University of Warsaw, Warsaw, Poland; ²Institute of Cardiology, Warsaw, Poland; and ³Cardiovascular Research Foundation, New York, New York.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.

The authors report that patient consent was provided for publication of the images used herein.

Manuscript accepted October 26, 2018.

Address for correspondence: Michał Świerczewski, Institute of Cardiology, Department of Coronary and Structural Heart Diseases, Alpejska 42 Street, 04-628 Warsaw, Poland. Email: swierczewski.michal@yahoo.pl