Recanalization Rates Decrease with Increasing Thrombectomy Attempts

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Fig 1.
Decision tree results at each of ≤6 retrieval attempts.
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Fig 2.
Graph shows the number of attempts used to achieve final outcome AOL score.
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Fig 3.
Graph shows aggregate odds that a given attempt number will recanalize.
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Fig 4.
Graph shows aggregate distribution of AOL scores following each attempt.

Table 1:

Comparison by final AOL score and optimal number of attempts

Demographic	Final AOL Score		PValue	Optimal	Suboptimal	PValue
Demographic	0–1 (n = 23)	2–3 (n = 71)	PValue	n = 61	n= 33	PValue
Age	67.6 ± 18.3	65.0 ± 19.7	.58	65.4 ± 19.8	65.7 ± 18.6	.94
Male sex	11 (47.8)	30 (42.2)	.82	25 (41.0)	16 (48.5)	.52
Prior history
Hypertension	11 (47.8)	41 (57.7)	.55	36 (59.0)	16 (48.5)	.39
Diabetes	6 (26.1)	12 (16.9)	.51	12 (19.7)	6 (18.2)	1
Dyslipidemia	5 (21.7)	22 (31.0)	.56	19 (31.1)	8 (24.2)	.63
Peripheral vascular disease	1 (4.3)	1 (1.4)	.43	1 (1.6)	1 (3.0)	1
Atrial fibrillation	10 (43.5)	36 (50.7)	.72	32 (52.5)	14 (42.4)	.39
Time to pass	6:43 ± 2:55	6:57 ± 2:55	.74	7:02 ± 3:05	6:41 ± 2:38	.60
Intravenous thrombolytic	6 (26.1)	21 (29.6)	1	19 (31.1)	8 (24.2)	.63
Intra-arterial thrombolytic	3 (13.0)	4 (5.6)	.36	3 (4.9)	4 (12.1)	.24
Total attempts, median (IQR)	4 (2)	2 (2)	<.0001
Complications				9 (14.8)	14 (42.4)	.006
Subarachnoid hemorrhage				6 (9.8)	10 (30.3)
Dissection				1 (1.6)	1 (3.0)
Air embolism				1 (1.6)	2 (6.0)
Device fracture				2 (3.2)	2 (6.0)
Intraventricular hemorrhage				0	2 (6.0)
Perforation				1 (1.6)	0
Parenchymal HT, 72 hours^a	2 (13)	11 (16)	1	10 (19)	3 (10)	0.5

a Eleven patients were not included because they were not able to undergo imaging 72 hours after intervention; none of these patients had HT on post-Merci CT; 7 of these patients had a poor final-outcome AOL score, while 4 had good final-outcome AOL scores. Seven of these patients underwent the optimal number of attempts, while 4 did not.

Table 2:

Distribution of final outcome AOL scores by number of attempts

Table 3:

Probability next attempt will improve existing recanalization result after a given number of attempts

Table 4:

Probability that the maximum number of attempts (6) will produce a final AOL result superior to a prospective prespecified number of attempts

Good AOL Score, No. (%), after Attempting Up to:
Six Attempts		Pre-Specified Number		OR	95% CI
6	85 (73.9)	1	37 (32.2)	5.97	3.37–10.58
6	85 (73.9)	2	57 (49.6)	2.88	1.66–5.02
6	85 (73.9)	3	75 (65.2)	1.51	0.86–2.66
6	85 (73.9)	4	82 (71.3)	1.14	0.64–2.04
6	85 (73.9)	5	84 (73.0)	1.05	0.58–1.88