Utilization of frequency domain optical coherence tomography and fractional flow reserve to assess intermediate coronary artery stenoses: conciliating anatomic and physiologic information

Abstract

Fractional flow reserve (FFR) and intravascular imaging respectively provide hemodynamic and anatomical assessments of angiographic intermediate stenoses. Frequency domain optical coherence tomography (FD-OCT) is a promising high-resolution imaging modality, but its clinical use in determining severity of coronary disease has yet to be determined. There, we set out to determine the role of FD-OCT to complement FFR in the evaluation of intermediate coronary artery stenoses. FD-OCT was planned in 176 consecutive interventional procedures at our institution to delineate the proper use of FD-OCT in clinical practice. The decision to use other invasive assessments was at the discretion of the operator. This report describes an early series of the 14 patients who underwent FFR of 18 target stenoses in addition to FD-OCT. FD-OCT was successfully performed without complications in all cases. Fractional flow reserve was <0.80 in four patients, with minimal lumen areas and reference vessel diameters ranging from 1.03 to 3.47 mm(2) and 2.60 to 2.94 mm by FD-OCT, respectively. FD-OCT was important to rule out plaque rupture, erosion and thrombosis and to help guide decision to defer PCI in six patients with acute coronary syndrome and FFR > 0.80. FD-OCT was also valuable to guide PCI strategy in tandem lesions with an FFR < 0.80. This initial experience with FD-OCT suggests a potential complementary role of physiological and anatomical assessment to guide decision making in complex clinical scenarios. Future investigations are warranted to validate these findings and define the role of FD-OCT in assessing intermediate lesions.

Fig. 1

Representative case of a 72-year-old female who presented with a non-ST elevation myocardial infarction. Her presentation was initiated in the setting of emotional stress and her echocardiogram showed apical ballooning suggestive of Takotsubo cardiomyopathy. The angiogram (A, B) did not show significant disease in either the RCA (not shown) or LCx. C shows the 3-D reconstruction by FD-OCT of the region of interest, with the numbered dashed yellow lines representing the same regions identified in the angiograms. The origins of both the LCx (arrow) as well as the diagonal branch (dashed arrow) can be readily depicted. D, E show FD-OCT cross-sectional images of the points of interest with their respective lumen area values. Although FD-OCT revealed a relatively extensive diseased segment in the proximal LAD, and minimal lumen area of 2.58 mm², no signs of plaque instability were noticeable. A variety of plaque composition was noticed, predominantly lipidic (D2, D3), and calcified (marked by asterisk in D4). Normal distal reference is also illustrated (D1). The FFR value obtained distal to this segment was 0.89. Based on the composite of the above results, percutaneous intervention was deferred. RCA right coronary artery, LCx left circumflex artery, LAD left anterior descending artery, FD-OCT frequency domain optical coherence tomography, FFR fractional flow reserve; LV left ventricle, MLA minimal lumen area (mm²), LA lumen area (mm²)

Fig. 2

Representative case of a patient who presented with stable angina found to have tandem stenoses in the LAD. RAO cranial view (A) demonstrated diffuse disease in the mid to distal segments of the LAD and in the RAO caudal projection (B), one can identify a focal lesion in its proximal segment. C shows FD-OCT images of different points along the LAD in correspondence to the numbered dashed yellow lines from the angiographic pictures. The bottom arrow in the panel shows the distance from the LAD ostium. The MLA was 1.03 mm² (C1). Images (C2) and (C3) demonstrate calcified (asterisk) lesions. In the proximal LAD segment, one can identify a “non-diseased” segment (C5) followed by the proximal stenosis, which presented a lumen area of 4.30 mm². The FFR value distal to the whole segment of disease was 0.68. However, the FFR evaluation of the proximal lesion was 0.85. Based on these results, the decision was to limit intervention to the lesions located on the mid to distal portions of the LAD. Picture (D) exhibits the control angiography after the aforementioned treatment. E represents FD-OCT images post-treatment. In (E7) it was observed a significant stenosis distal to the stented segment (MLA 1.89 mm²). One can observe that along the entire treated segment (E8–12) that the stents are well expanded and apposed, including the overlapping regions (E9 and E11). Repeat FFR of the lesion distal to the stented segment was 0.71, which prompted subsequent intervention to that lesion (not shown). LAD left anterior descending artery, RAO right anterior oblique, FD-OCT frequency domain optical coherence tomography, MLA minimal lumen area, FFR fractional flow reserve, LA lumen area, SA stent area