Impact of aspiration catheter inner diameter on first-pass effect: A systematic review and meta-analysis

Abstract

Background

The first-pass effect (FPE) refers to the complete or near-complete revascularization with a single pass of mechanical thrombectomy devices. While previous claims suggest a link between larger catheters and the effectiveness of contact aspiration (CA) thrombectomy, no extensive research has confirmed if larger distal inner diameter (ID) catheters achieve higher FPE rates.

Methods

We searched PubMed, Scopus, and Web of Science to assess the impact of aspiration catheter distal ID size on FPE. The primary outcome was FPE rate, defined as thrombolysis in cerebral ischemia (TICI) grades 2c-3 at first pass, and the secondary outcome was modified FPE (TICI 2b-3 in a single pass). Aspiration catheters were categorized based on distal ID: 0.060–0.069 (medium bore), 0.070–0.074 (large bore), and greater than 0.074 inches (super-large bore). Rates of FPE were pooled using random effect models and compared using a Chi-square test.

Results

Our study included 34 articles with 4831 patients. FPE rates were 27.7% (95% CI, 15.1–45.3) for medium bore, 46.6% (95% CI, 33.7–59.9) for large, and 58.3% (95% CI, 44.8–70.7) for super-large catheters. The FPE rate was significantly higher for super-large bore catheters compared with other groups (χ² = 7.26, p = 0.03). A similar trend was observed for modified FPE rates, which were 51.1% (95% CI, 45.3–56.8) for medium bore, 60.0% (95% CI, 52.8–66.8) for large bore, and 80% (95% CI, 56.3–94.2) for super-large bore catheters (χ² = 8.14, p = 0.03).

Conclusion

Our analysis indicates that larger CA catheters are correlated with higher FPE rates.

Introduction

Since the advent of mechanical thrombectomy (MT) for acute ischemic stroke (AIS) due to large-vessel occlusion, ¹ shorter time to revascularization has been considered a key factor to improve neurological outcome. ² Time to revascularization is correlated with the first-pass effect (FPE), which is defined as the successful or whole revascularization of an occluded target artery with one pass of a mechanical thrombectomy device. ³ Evidence shows that patients undergoing MT had a higher chance of achieving a satisfactory functional outcome at 90 days and a lower death rate when FPE was achieved.^3,4 FPE might also be correlated with lower rates of complications arising from multiple passes. ⁵

Contact aspiration (CA) is widely used to perform MT instead of stent-retriever (SR). CA permitted faster recanalization times and lower procedural cost ⁶ while large multicenter randomized controlled studies have shown that first-line CA is non-inferior to first-line SRs. ⁷ Greater technical and clinical results may be facilitated by bigger aspiration catheters, according to more recent retrospective studies that have examined the role of the aspiration catheter's distal inner diameter (ID) as a variable in primary aspiration thrombectomy.^8–10 Although there have been claims of a relationship between bigger catheters and CA thrombectomy effectiveness, ¹¹ no extensive research has been conducted to determine if larger ID catheters are indeed linked to achieving enhanced FPE rates. In response, we performed a meta-analysis aimed at understanding the association between catheters’ ID and FPE rates based on published studies providing evidence about aspiration catheter sizes and the corresponding FPE rates of AIS patients.

Methods

This systematic review and meta-analysis adheres to the reporting guidelines provided by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. Screening, data extraction, and risk of bias assessments were performed by at least two independent authors who were blinded of each other results. Any discrepancies at each step were resolved through discussion and consensus. The protocol of this review was not registered.

Literature search

Three databases were searched from inception to April 2024: PubMed, Scopus, and Web of Science. The initial search terms were stroke, thrombectomy, first pass, and their related terms. During the search process, we included reports without any restrictions on language, country, or date. Full search strategy for PubMed can be found in Supplementary Materials. Further detail on search can be found in Supplementary Materials.

Selection process

We included retrospective or prospective cohort studies if they reported the first pass recanalization rate of a CA technique along with direct or indirect (e.g. brand name) data on the catheter size. Studies that used the SR technique or combined SR and CA were excluded if they did not report outcomes of CA subgroup. Also, non-human studies, case series with <10 cases, conference abstracts, editorials, and reviews were excluded. To analyze the impact of the size of the catheter's distal ID, we categorized them in three groups, as follows: 0.060–0.069 inch (medium bore catheters), 0.70–0.074 inch (large bore catheters), and >0.074 inch (super-large bore catheters). This classification follows the trend observed with the development of aspiration catheters for MT and is used in the literature. ¹² We excluded studies that used aspiration catheters with distal IDs smaller than 0.060 inches, as these are primarily used for distal medium vessel occlusion MT. Including such studies could introduce a confounding factor related to occlusion location. Additionally, we excluded studies that used devices with a wide range of catheter sizes (e.g. 0.035–0.072 inches) without providing individual results for each catheter size.

Data extraction

Details of devices and outcomes were extracted including brand name, diameter of distal ID of each catheter, and the FPE rate based on the operator or core lab reports for each device. If a study used multiple devices, we extracted FPE rate for each device separately. Successful reperfusion was defined based on thrombolysis in cerebral infarction (TICI) scores, modified TICI (mTICI) or extended TICI (eTICI) scores. The primary outcome was FPE defined as reaching TICI 2c-3 on the first pass and the secondary outcome was modified FPE defined as reaching TICI 2b-3 and TICI 3 on the first pass.

Risk of bias assessment

The risk of bias in the studies was assessed using the methodological index for non-randomized studies, a tool designed to evaluate the quality of non-randomized studies in systematic reviews and meta-analyses. Details for risk of bias assessment can be found in Supplementary Materials.

Statistical analysis

All analyses were conducted using R software version 4.3.2 (R Project for Statistical Computing) meta package version 6.5–0. The rates (percentage) of FPE and modified FPE and their corresponding 95% CIs were pooled using generalized linear mixed models, considering methodological heterogeneities.^13,14 Heterogeneity was assessed using Q statistic and the I² test, in which I² greater than 50% or p < .05 were considered significant. Subgroup analyses were performed based on three categories of medium, large, and super-large bore catheters based on different FPE definitions. The difference between groups was assessed using a Chi-squared test.

Results

After removing duplicate records, we screened the titles and abstracts of 1229 records against our eligibility criteria. Out of these, 98 full-text articles were deemed suitable for further examination from which, we excluded 64 papers: 58 were unrelated to the aspiration technique or had ineligible catheter sizes, 4 were review articles, and 2 had overlapping populations with newer studies from the same author groups (Figure 1). Finally, our study included 34 articles including data for 4831 patients (mean age ranged from 64.1–77.5 years), who underwent CA thrombectomy with 27 different devices with distal ID of ≥0.060 inch.^{7–10,12,15–43}

Figure 1.

PRISMA flowchart of study selection. PRISMA: Preferred Reporting Items for Systematic Reviews and Meta-Analyses.

Details of study quality assessment is presented as Supplementary Table 2. Four studies (12%) had low risk of bias, 25 studies (72%) had some concerns, and five studies (15%) had high risk of bias.

The studies included 29, 33, and 4 comparisons for distal ID sizes of 0.060–0.069, 0.070–0.074 and >0.074 inch, respectively, and provided information regarding of FPE as TICI 2b-3, TICI 2c-3, and TICI 3 in 42, 17, and 7 comparisons, respectively (Table 1). The studies spanned from 2018 to 2024. Half of the studies (n = 17) were from North America (United States and Canada), 11 studies (32%) were from Europe, and 6 studies (18%) were from Asia. Concomitant IVT was used in 8–85% of patients across different studies. Only one study focused exclusively on posterior circulation strokes, whereas 17 studies included only anterior circulation strokes, and the remaining included both. Detailed study characteristics and patient demographic data are presented in Supplementary Table 3. Details of individual study FPE rates based on device and size of distal ID is provided in Supplementary Table 4.

Table 1.

Data availability based on FPE definition.

FPE definition	Size: 0.060–0.069	Size: 0.070–0.074	Size: >0.074	Sum
N comparisons for TICI 2b-3	22	19	1	42
N comparisons for TICI 2c-3	4	10	3	17
N comparisons for TICI 3	3	4	0	7
Sum	29	33	4	66

FPE: first-pass effect; TICI: thrombolysis in cerebral ischemia.

Overall, the rate of FPE defined as TICI 2b-3, TICI 2c-3, and TICI 3, including all sizes of distal ID was 55.3% (95%CI, 50.5–60.0, I² = 84%, p < 0.01), 43.9% (95%CI, 33.7–54.6, I² = 89%, p < 0.01), and 33.7% (95%CI, 22.2–47.5, I² = 82%, p < 0.01), respectively (Supplementary Figures 1–3).

Primary outcome

Pooling data of 1966 patients showed FPE (TICI 2c-3) rate of 27.7% (95%CI, 15.1–45.3), 46.6% (95%CI, 33.7–59.9), and 58.3% (95%CI 44.8–70.7) for sizes of 0.060–0.069, 0.070–0.074, and >0.074, respectively. The difference in rate of FPE between subgroups was statistically significant (χ2 = 7.26, p = 0.03) (Figure 2).

Figure 2.

FPE (TICI 2c-3) based on distal ID size. FPE: first-pass effect; ID: inner diameter; TICI: thrombolysis in cerebral ischemia.

Secondary outcomes

Pooling data of 3407 patients from studies that reported modified FPE (TICI 2b-3), the rate was 51.1% (95%CI, 45.3–56.8), 60.0% (95%CI, 52.8–66.8) for distal ID sizes of 0.060–0.069 and 0.070–0.074, respectively. The only study containing data for >0.074 size showed a significantly higher rate of modified FPE 80% (95%CI, 56.3–94.2) comparing with the other two groups (χ2 = 8.14, p = 0.03) (Figure 3).

Figure 3.

Modified FPE rate (TICI 2b-3) based on distal ID size. FPE: first-pass effect; ID: inner diameter; TICI: thrombolysis in cerebral ischemia.

Among studies that measured FPE as achieving TICI 3 at first pass, the rate of FPE was 28.5% (95%CI, 8.5–63.1), 34.8% (95%CI, 23.2–48.6) for sizes of 0.060–0.069 and 0.070–0.074, respectively. There was no study for size >0.074 in this category. The difference in rate of FPE between these two groups was not statistically significant (χ2 = 0.14, p = 0.71) (Figure 4).

Figure 4.

Modified FPE rate (TICI 3) based on distal ID size. FPE: first-pass effect; ID: inner diameter; TICI: thrombolysis in cerebral ischemia.

Discussion

This meta-analysis provides valuable insights into the association between catheter size and FPE during CA for large-vessel occlusions. Our meta-analysis demonstrates that larger ID in aspiration thrombectomy catheters is strongly correlated with higher rates of both FPE and modified FPE. Notably, this study reveals a clear trend: FPE rates increased from less than 30% for medium bore catheters to nearly 60% for the largest devices. These findings are crucial as they suggest that using larger catheters could significantly enhance revascularization success, ultimately improving patient outcomes in AIS treatment.

Initial CA catheters involved the use of the 5 Max ACE (0.060”) reperfusion catheter (Penumbra, Alameda, California), ⁶ followed by ACE64 (0.064”) and ACE68 (0.068”) catheters (Penumbra). ⁸ Several other aspiration catheters were developed within the same range of size. Technical improvements in deliverability, flexibility, and larger bore catheter led to the apparition of the Sofia Plus (Microvention) catheter (0.070”) ⁴⁴ rapidly followed by larger catheters until 0.074”. ⁴⁵ Finally, technical improvement reached a new step with the appearance of the so-called “super large bore” catheters (0.088”). ⁴⁶

Several factors have been reported to be associated with FPE including occlusion location, underlying intracranial atherosclerosis, combined device use, and older age among others.^47–49 Moreover, larger bore aspiration catheters have been found to provide improved FPE and clinical outcomes. Alawieh et al. reported that the Penumbra 0.064-inch and 0.068-inch aspiration catheters achieved improved recanalization rates, reduced procedure times, and fewer instances requiring SR rescue compared to the smaller Penumbra 5MAX/ACE (0.054/0.060-inch) catheters. ¹⁰ Consistently, Al Kassab et al. showed increased FPE rates, and faster and improved recanalization times with medium (0.064–0.068 inch) and large (0.071–0.074 inch) aspiration catheters compared to small (0.041–0.060 inch) catheters. ⁵⁰ The pattern observed in the literature is in line with our result that as the size of the catheter increases, the likelihood of achieving FPE would also increase. This pattern was observed across various definitions of FPE (TICI 2b-3, TICI 2c-3 at first pass). The definition of FPE as TICI 3, which represents the strictest criterion for successful recanalization, also followed this trend, although the differences between ID size groups were not statistically significant (p = 0.71). The lack of significance in the latter analysis could be attributed to the limited number of studies using this definition and the absence of data for catheters >0.074. These findings support the idea that larger catheter sizes are more effective at clot retrieval, potentially because they provide a greater aspiration force and allow for more efficient passage of the device through the arterial system, resulting in higher rates of complete or near-complete recanalization on the first attempt.^51,52

The clinical decision to use a larger bore aspiration catheter should be weighed against its potential clinical and technical disadvantages. The stronger vacuum forces generated by larger catheters may increase the likelihood of arterial collapse during aspiration leading to flow cessation and frictional damage to the arterial walls. ⁵³ This is observed as an increased risk of postprocedural intracranial hemorrhage in larger bore aspiration catheters. ¹¹ In the case of distal occlusions, larger catheters may be blocked by vessel walls reducing the aspiration force. ⁵⁴ Additionally, distal navigation of larger catheters to the clot face can be more challenging due to their reduced maneuverability. Lastly, these devices often require femoral access due to their size, which can increase the risk of pain, access site complications, and patient comfortability compared to the more recently adopted radial access. ⁵⁵

When performing aspiration thrombectomy for large-vessel occlusions, it is crucial to consider the size of the vessel in addition to the catheter size. Recently, Charbonnier et al. found that a higher diameter ratio (>0.71 between catheter size and occluded vessel) is linked to higher recanalization rates, suggesting that selecting appropriately sized catheters relative to the vessel size can enhance the success of the procedure. ⁵⁴ Tailoring catheter selection to the specific vessel size ensures that the catheter is both effective and safe, reducing the risk of arterial collapse and frictional damage. However, a limitation of our study is that data on vessel size was not available. The lack of vessel size data makes it challenging to draw definitive conclusions about the optimal catheter sizes for different vessel diameters and highlights the need for further research to address this gap.

Several limitations should be considered when interpreting the findings of the current study. Various definitions of FPE were used in the included studies, which may lead to increased heterogeneity in the overall analysis. This limitation was minimized by conducting subgroup analyses according to the definition of FPE. The number of studies examining catheter sizes >0.074 was relatively small, which limits the generalizability of the findings for this specific size category and warrants caution in drawing definitive conclusions. Additionally, the inherent bias of studies resulting from differences in operator experience, thrombectomy techniques, and the use of different aspiration devices across studies may also have contributed to the variability in outcomes. Moreover, many of these studies were self-adjudicated in terms of TICI scoring, which could introduce additional bias into the assessment of recanalization success.

Conclusion

Our comprehensive analysis demonstrates a clear correlation between the size of aspiration catheters and the rates of successful FPE. Larger distal ID catheters were significantly associated with higher FPE and modified FPE rates. These findings underscore the potential benefits of using larger CA catheters to achieve more effective revascularization in patients with AIS. Further research is warranted to validate these results and optimize catheter selection for enhancing patient outcomes.