Parent Artery Straightening after Flow-Diverter Stenting Improves the Odds of Aneurysm Occlusion

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FIG 1.
Measurement of parent artery straightening. Angles were measured at the intersection of 2 lines drawn from the neck center in the axis of the proximal and distal segments of the parent artery. α is the angle measured before stent placement, and β is the angle measured after stent deployment. Preoperative (1) and postoperative (2) drawings.
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FIG 2.
Distribution of angles of parent artery straightening and association with aneurysmal occlusion. A, Shadowgram distribution of parent artery straightening. B, Stacked histograms of the proportion of patients with complete occlusion in bins of increasing parent artery straightening (offset = 0, width = 25°).
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FIG 3.
Comparison of vascular geometry modifications in 2 treatments of MCA aneurysms. The second flow-diverter stent deployment appears to modify the vascular anatomy (E–G) more than the first flow-diverter stent (A–C). Angiogram controls show complete aneurysm occlusion with the second flow-diverter stent (H) compared with the first-flow diverter (D) stent. A and E, Preoperative angiogram. B and F, Angiogram after stent placement. C and G, Unsubtracted view after stent deployment. D and H, First angiogram follow-up. α indicates the angle measured before stent placement; β, the angle measured after stent placement.

Table 1:

Comparison of demographic, angiographic, and treatment characteristics between complete occluded and incomplete occluded aneurysms^{^a}

	All Aneurysms (n = 99)	Complete Occlusion (n = 64)	Incomplete Occlusion (n = 20)	P Value
Age (yr) (mean)	54.1 (SD, 11.2)	53.8 (SD, 10.8)	54.3 (SD, 10.4)	.76
Sex, M/F	31 (31.3%)/68 (68.7%)	18 (28.1%)/46 (71.9%)	9 (45%)/11 (55%)	.26
Follow-up (mo) (n = 84)	23.9 (SD, 16.3)	24.2 (SD, 15.0)	22.9 (SD, 20.2)	.27
Previous treatment	45 (45.5%)	28 (43.8%)	13 (65%)	.16
Aneurysm location				.62
MCA	44 (44.4%)	25 (39.1%)	12 (60%)
AcomA	27 (27.3%)	20 (31.3%)	5 (25%)
A1	2 (2.0%)	2 (3.1%)	0
A2	2 (2.0%)	2 (3.1%)	0
Pericallosal	24 (24.2%)	15 (23.4%)	3 (15%)
Aneurysm size (mm)
Neck	3.9 (SD, 2.1)	3.6 (SD, 2.1)	4.3 (SD, 2.0)	.06
Diameter	6.1 (SD, 5.0)	6.1 (SD, 5.7)	6.5 (SD, 3.5)	.14
Concomitant coiling	15 (15.2%)	9 (14.1%)	2 (10%)	1
Flow-diverter stent
Length (mm)	16.9 (SD, 3.9)	16.5 (SD, 3.8)	18.2 (SD, 4.3)	.42
Type				.004
Nitinol	47 (47.5%)	26 (40.6%)	16 (80%)
Cobalt chromium	52 (52.5%)	38 (59.4%)	4 (20%)
Angle of parent artery
Initial angle	124.1° (SD, 64.0°)	118.3° (SD, 29.8°)	122.7° (SD, 28.1°)	.58
Postdeployment angle	141.6° (SD, 24.8°)	146.0° (SD, 21.8°)	135.9° (SD, 24°)	.12
Parent artery straightening	3.8° (SD, 21.6°)	27.7 (SD, 22.6)	13.3° (SD, 12.3°)	<.001

Note:—AcomA indicates anterior communicating artery; A1, proximal segment of the anterior cerebral artery; A2, distal segment of the anterior cerebral artery.
↵a Data are presented as mean (standard deviation, SD) for continuous variables and absolute number (percentage of column total) for discrete variables.

Table 2:

Multivariable analysis of aneurysm occlusion determinants

Variables	Multivariate Analysis, aOR (95% CI)	P Value
Aneurysm neck (mm)	0.57 (0.38–0.87)	<.001
Stent type: chromium cobalt	2.13(1.26–11.93)	.020
Parent artery straightening	1.04° (1.01°–1.17°)	.036
Initial angle	0.95°(0.91°–1.02°	.401
Parent artery straightening × stent type^{^a}	0.99 (0.94–1.02)	.055