RFC-ACS
IFC-ACS
Stable angina
p-value
Patients (n)
25
10
22
Age (years)
63.7 ± 10.1
61.5 ± 8.2
62.6 ± 8.2
Male (n, %)
25 (100)
8 (80)
22 (100)
0.007
Clinical presentation (n, %)
NSTEMI
15 (60)
4 (40)
–
–
UAP
10 (40)
6 (60)
–
–
Stable angina pectoris
–
–
22 (100)
–
Diabetes (n, %)
8 (32)
3 (30)
8 (36)
0.922
Hypertension (%)
12 (48)
6 (60)
13 (59)
0.692
Hypercholesterolemia (%)
12 (48)
6 (60)
10 (45)
0.739
Smokers (n, %)
Nonsmoker
10 (38)
1 (9)
7 (35)
0.001
Ex-smoker
9 (46)
2 (18)
12 (60)
–
Current smoker
6 (17)
7 (73)
3 (5)
–
Culprit lesions (n)
25
10
22
Coronary artery (n, %)
RCA/ LAD/ LCX
11/13/1
4/5/1
5/14/3
0.522
ACC/AHA lesion type (n)
A/B1/B2/C
0/13/12/0
1/4/5/0
2/11/9/0
0.839
QCA
RD pre (mm)
2.55 ± 0.52
2.46 ± 0.46
2.64 ± 0.58
0.666
MLD pre (mm)
0.94 ± 0.20
1.09 ± 0.22
0.96 ± 0.25
0.179
Lesion length (mm)
20.7 ± 7.0
22.5 ± 7.2
22.9 ± 9.4
0.647
Non-culprit lesions in non-culprit vessel assessed by CT angiography
Non-culprit lesions (n)
19
8
12
Average lesion severity (%)
42 ± 19 %
32 ± 12 %
46 ± 20 %
0.265
NCP ≤ 30 HU (n, %)
7 (37 %)
2 (25 %)
1 (8 %)
0.208
Spotty calcification (n, %)
5 (26 %)
2 (25 %)
2 (16 %)
0.815
Positive remodelling (n, %)
10 (53 %)
1 (13 %)
2 (16 %)
0.044
Table 2.2
Comparison of OCT, coronary angioscopy, IVUS and CTA findings in 57 lesions with RFC-ACS, IFC-ACS and stable plaque aetiology
RFC-ACS | IFC-ACS | Stable Angina | p-value | |
|---|---|---|---|---|
Lesion (n) | 25 | 10 | 22 | – |
OCT | ||||
Fibrous cap thickness (μm) | 45 ± 12A1)* | 131 ± 57B1)* | 321 ± 146C1)* | 0.001 |
Lipid angle >2 quads (n, %) | 23 (92 %) | 4 (40 %) | 5 (23 %) | 0.001 |
TCFA (n, %) | 23 (92 %) | 2 (20 %) | 2 (9 %) | 0.001 |
Thrombus (n, %) | 25 (100 %) | 10 (100 %) | 4 (18 %) | 0.001 |
Coronary angioscopy | ||||
Thrombus (n, %) | 22 (88 %) | 10 (100 %) | 3 (14 %) | 0.001 |
Mural thrombus (n, %) | 13 (52 %) | 7 (70 %) | 3 (14 %) | – |
Protruding thrombus (n, %) | 9 (36 %) | 3 (30 %) | 0 (0 %) | – |
Yellow plaque (n, %) | 21 (84 %) | 7 (70 %) | 12 (55 %) | 0.088 |
Light yellow plaque (n, %) | 5 (16 %) | 3 (30 %) | 5 (23 %) | – |
Deep yellow plaque (n, %) | 18 (68 %) | 4 (40 %) | 7 (31 %) | – |
White plaque (n, %) | 4 (16 %) | 3 (30 %) | 10 (45 %) | 0.088 |
IVUS | ||||
Vessel area pre (mm2) | 14.8 ± 3.2 | 12.8 ± 2.1 | 12.6 ± 5.1 | 0.133 |
Lumen area pre (mm2) | 2.0 ± 0.8 | 2.5 ± 0.8 | 1.9 ± 0.8 | 0.132 |
Plaque area pre (mm2) | 12.9 ± 3.0 | 10.2 ± 2.1 | 10.7 ± 4.9 | 0.083 |
Prox. ref. vessel area (mm2) | 14.3 ± 2.9 | 13.5 ± 1.9 | 14.1 ± 5.0 | 0.862 |
Distal ref. vessel area (mm2) | 11.7 ± 2.9 | 11.8 ± 1.8 | 12.6 ± 5.3 | 0.781 |
Remodelling index | 1.14 ± 0.12A2)* | 1.00 ± 0.08B2)* | 0.95 ± 0.11C2)* | 0.001 |
CTA | ||||
NCP ≤30 HU (LAP; n, %) | 22 (88 %) | 4 (40 %) | 4 (18 %) | 0.001 |
NCP from 30 to 150 HU (n, %) | 25 (100 %) | 10 (100 %) | 22 (100 %) | – |
Spotty calcification (n, %) | 20 (80 %) | 2 (20 %) | 5 (23 %) | 0.001 |
Large calcification (n, %) | 3 (12 %) | 1 (10 %) | 13 (59 %) | 0.001 |
Remodelling index (%) | 1.15 ± 0.06A3)* | 1.02 ± 0.08B3)* | 0.99 ± 0.09C3)* | 0.001 |
Positive remodelling (PR; n, %) | 24 (96 %) | 2 (20 %) | 3 (14 %) | 0.001 |
LAP and PR (n, %) | 22 (88 %) | 1 (10 %) | 0 (0 %) | 0.001 |
2.3.2 Culprit Lesion Characteristics by OCT in RFC-ACS, IFC-ACS and Stable Angina
Intracoronary imaging findings are shown in Table 2.2. Whilst OCT revealed that fibrous cap thickness was significantly thinner in RFC lesions than other lesions (45 ± 12, 131 ± 57, 321 ± 146 μm, respectively; p < 0.001), the prevalence of lesions with lipid pools greater than 2 quadrants was higher in RFC lesions than in IFC and stable angina lesions (92 %, 40 %, 23 %; p < 0.001). TCFA was more commonly observed in the RFC group than in the IFC or stable angina groups (92 %, 20 %, 9 %; p < 0.001). Thrombus was more frequently observed in RFC and IFC lesions compared with the stable lesions by OCT (Table 2.2) (Figs. 2.1, 2.2 and 2.3).
Fig. 2.1
Ruptured fibrous cap (RFC-ACS) plaque. OCT (a1, a2), coronary angioscopy (b), IVUS (c), angiography (d), volume rendering (e), curved MPR (f1) and the cross-sectional images (f2) were obtained in a culprit lesion with plaque rupture in 67-year-old male presenting with ACS. OCT revealed fibrous cap disruption (a1) and thrombus formation in adjacent slices (a2). Coronary angioscopy (b) showed yellow plaque and red thrombus formation through the blue coronary angioscopy guide catheter. IVUS (c) indicates two focal calcium deposits <90°. Angiography (d) and volume-rendered CT images (e) disclose a significant stenosis in the middle segment of the left anterior descending coronary artery. Curved MPR CT images (f1) reveal positive remodelling associated with focal calcium deposits. Curved MPR and the cross-sectional images (f2) display the presence of soft plaque with an attenuation of <30 HU [13]
Fig. 2.2
Intact fibrous cap (IFC-ACS) plaque. OCT (a), coronary angioscopy (b), IVUS (c), angiography (d), volume-rendered (e) and curved MPR (f) images were derived from a culprit lesion with intact fibrous caps in a 63-year-old male presenting with an ACS. OCT revealed no evidence of fibrous cap rupture (a) but the presence of thrombus formation. Coronary angioscopy (b) showed red thrombus formation through the blue coronary angioscopy guide catheter. IVUS (c) reveals a soft and homogenous plaque with poor echo-reflectivity. Angiography (d) and the volume-rendered CT images (e) disclose a significant stenosis in the proximal segment of the right coronary artery. Curved MPR CT images (f) indicate the absence of positive remodelling and a non-calcified plaque [13]
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