18 / 74
CARDIOVASCULAR JOURNAL OF AFRICA • Volume 29, No 5, September/October 2018
280
AFRICA
50–69%, there was a low degree of concordance between the
operators (
κ
: 0.323 and
κ
: 0.261, respectively) (Table 3).
QCA was performed on all PCI-treated lesions by another
operator who was blinded to the results of the visual assessment.
The mean minimal lumen diameter was 1.19
±
0.48 mm (range
0.09–2.53). The mean reference diameter was calculated as 2.90
±
0.58 mm (range 1.75–5.22) and the mean length of the lesions
was 17.3
±
8.1 mm (range 6.7–45.1). Mean percentage diameter
of stenosis was 58.4
±
14.5% (range 29–97). Mean percentage
area of stenosis was 80.6
±
11.2% (range 50–99). The most
commonly calculated category, mean percentage area of stenosis
was 70–90%. There was a statistically significant difference
between the QCA parameters percentage diameter of stenosis
and percentage area of stenosis (58.4
±
14.5% vs 80.6
±
11.2%,
p
<
0.001).
The difference between the primary operator’s visual
assessment and the QCA measurement was evaluated with the
Student’s
t
-test. There was a statistically significant difference
between the visual estimation of percentage of coronary stenosis,
and the percentage diameter of stenosis and percentage area of
stenosis determined by QCA (
p
<
0.01). Visual estimation of
percentage of stenosis was higher than percentage diameter of
stenosis and percentage area of stenosis calculated by QCA. A
statistically significant difference was found between the stent
size and reference diameter measured by QCA, and there was
also a significant difference between stent length and lesion
length determined by QCA (
p
<
0.001) (Table 4).
Concordance between visual estimation and QCA was
investigated with kappa analysis. There was a low to moderate
grade of concordance between the categories of visual estimation
and the percentage area of stenosis (
κ
: 0.30) (Table 5) but there
was no concordance between the categories of visual estimation
and percentage diameter of stenosis on QCA (
κ
: –0.061) (Table
6). Of the 155 lesions considered above 70% on visual estimation,
23 were found by QCA not to be significant.
Discussion
Many catheterisation laboratories still depend on visual
estimation of lesion severity rather than quantitative analysis
when deciding on PCI. Unfortunately, visual estimation may not
be accurate and may vary between operators. Moreover, it has
many limitations. The error with visual estimation may exceed
Table 1. Characteristics of the patients and lesions
Characteristics
Total: 147 patients/155 lesions
Mean age, years
64.7
±
11.3
Female,
n
(%)
40 (27.2)
Male,
n
(%)
107 (72.8)
Vessel
LAD,
n
(%)
68 (46.4)
Cx,
n
(%)
39 (25.2)
RCA,
n
(%)
42 (27.1)
Intermediate,
n
(%)
2 (1.3)
Percentage stenosis
Mean (range)
84 (55–99)
Intervention,
n
Stent
159
Balloon
5
Stent type,
n
BMS
92
DES
56
BMS + DES
2
Stent size (mm)
Length (mean)
19.1
±
6.6
Diameter (mean)
3.13
±
0.49
QCA
Minimal lumen diameter (mm)
Mean
1.19
±
0.48
Range
0.09–2.53
Reference diameter (mm)
Mean
2.90
±
0.58
Range
1.75–5.22
LAD, left anterior descending artery; Cx, circumflex artery; RCA, right coro-
nary artery; BMS, bare-metal stent; DES, drug-eluting stent; QCA, quantitative
coronary analysis.
Table 2. Visual estimations of three operators
Operators
Visual estimation,
n
(%)
Primary operator
Percentage stenosis (mean)
84.0
> 50%
0 (0)
50–69%
68 (3.9)
70–89%
75 (48.4)
90–99%
74 (47.7)
2nd operator
Percentage stenosis (mean)
80.4
< 50%
3 (1.9)
50–69%
12 (7.7)
70–89%
82 (52.9)
90–99%
58 (37.4)
3rd operator
Percentage stenosis (mean)
80.4
< 50%
3 (1.9)
50–69%
20 (12.9)
70–89%
73 (47.1)
90–99%
59 (38.1)
Table 3. Evaluation of concordance between
operators with kappa analysis
Group
Kappa
Concordance
< 50%
0.261
low–moderate
50–69%
0.406
moderate
70–89%
0.581
moderate
90–99%
0.323
low–moderate
Total
0.458
moderate
Table 4. Comparison between visual estimation and quantitative analysis
Visual analysis
QCA estimation
Mean
Std
deviation
t
-value
p
-value
Percentage visual
84.01 10.846
3.996 0.000**
Percentage minimum lumen area
80.61 11.229
Percentage visual
84.01 10.846
25.440 0.000**
Percentage minimum lumen diameter
58.42 14.513
Stent diameter (visual)
3.13 0.491
6.611 0.000**
Reference diameter
2.91 0.586
Stent length (visual)
19.15 6.647
3.891 0.000**
Lesion length
17.36 8.135
Percentge area of stenosis (visual)
80.61 11.229
60.500 0.000**
Percentage diameter of stenosis
58.42 14.513
**
p
<
0.01.