Comparing Upfront Catheter-Based Thrombectomy With Alternative Treatment Strategies for Clot-in-Transit

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J INVASIVE CARDIOL 2024. doi:10.25270/jic/24.00220. Epub August 20, 2024.

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Clot-in-transit (CIT) is associated with high mortality, and optimal treatment strategies remain uncertain. This study compares the efficacy of catheter-based thrombectomy (CBT) with other treatments for CIT, including anticoagulation, systemic thrombolytic (ST) therapy, and surgical thrombectomy. We conducted a retrospective analysis of patients with CIT documented on echocardiography between January 2020 and May 2024, managed with urgent upfront CBT. We compared the all-cause mortality rates of the CBT cohort to performance goal rates for anticoagulation, systemic thrombolysis (ST), and surgical thrombectomy from a published meta-analysis. Our cohort included 26 patients who underwent CBT (mean age 59.3 ± 17.9 years, 42.3% women, 57.7% Black). Compared to 463 patients from the meta-analysis receiving alternative treatments, the CBT group's short-term mortality was significantly lower (7.7% vs 32.4% for anticoagulation, 13.8% for ST, and 23.2% for surgical thrombectomy). CBT demonstrated noninferiority to anticoagulation (P < .001), ST (P = .031) and surgical thrombectomy (P < .001), and was superior to anticoagulation (P = .0056) and surgical thrombectomy (P = .036). This study suggests CBT is a promising treatment for CIT. Further prospective studies are warranted to validate these findings.

Clot-in-transit (CIT) is associated with a high mortality rate and the optimal treatment remains uncertain.¹ Currently, the 4 most frequently utilized treatment approaches are anticoagulation alone, systemic thrombolytic (ST) therapy, surgical thrombectomy, and catheter-based thrombectomy (CBT). There has been an increasing interest in CBT among patients with acute pulmonary embolism (PE),^2-5 and this interest has extended to the CIT population as well.⁶  In a recent publication, we showed that CBT reduced in-hospital mortality and other cardiovascular events in patients with CIT compared with anticoagulation alone.⁶ This study aims to assess the efficacy of CBT compared to other treatment modalities in patients with CIT.

The study was approved by the New York University Institutional Review Board with a waiver of informed consent. The data that support the findings of this study are available on reasonable request from the corresponding author. The CBT cohort comprised of patients older than 18 years, with documented CIT on echocardiography between January 2020 and May 2024.

Management decisions on any CIT patient involved a multidisciplinary PE response team. Our institution adopts a routine invasive approach, employing urgent upfront CBT in patients who present with CIT with no contraindications. Baseline preprocedural and postprocedural clinical data were obtained from the electronic medical record. The primary outcome was short-term mortality. We compared the all-cause mortality rates of the CBT cohort to performance goal rates for anticoagulation, systemic thrombolysis (ST), and surgical thrombectomy from a published meta-analysis. The synthesis method was employed to determine the non-inferiority margin (M1) based on the historical study’s point estimate (Figure A). The M2 (inferiority margin) was calculated as 50% of M1, consistent with previous cardiovascular device trials (Figure).⁷ The pre-specified non-inferiority margins for short-term all-cause mortality for anticoagulation, ST, and surgical thrombectomy were 16.2%, 6.9%, and 11.6%, respectively (Figure). Non-inferiority was confirmed when the 95% CI did not cross or exceed the pre-specified margin for each outcome variable. Non-inferiority P-values were calculated using the Wald method with a 1-sided significance level of 0.025. If noninferiority was established, then sequential superiority testing was performed. Analyses were performed using Stata software (StataCorp LP).

There was a total of 26 patients in the CBT group with a mean age of 59.3 ± 17.9 years; 42.3% were women and 57.7% were Black. A total of 463 patients from a prior published meta-analysis underwent alternative treatment strategies; the mean age of the patients included in the meta-analysis was 60.6 years, and 49.9% were women. The median time to intervention was 5.8 hours (interquartile range 4.1, 19.8 hours) in the CBT group. Short-term mortality in the CBT group was 2 out of 26 patients (7.7%), which was lower when compared with historical data of anticoagulation (36/111, 32.4%), ST (26/188, 13.8%) and surgical thrombectomy (38/164, 23.2%). Using the prespecified noninferiority margin for each treatment, CBT was found to be noninferior to anticoagulation alone (P-value_NI < .001), ST (P-value_NI = .031) and surgical thrombectomy (P-value_NI <0.001), and superior to anticoagulation alone (P = .0056) and surgical thrombectomy (P = .036, Figure).

We analyzed 26 patients who underwent CBT in our cohort and 463 patients from a prior published meta-analysis who underwent alternative treatment strategies, making this the largest published series of CIT treated with CBT.¹ CIT poses a significant clinical challenge due to its association with high mortality rates and uncertain optimal treatment strategies. The rarity of CIT has made it difficult to conduct adequately powered prospective studies, leading to a dearth of high-quality evidence to support treatment strategies. Our findings demonstrated that CBT is not only a noninferior treatment compared to other strategies, but also superior to anticoagulation alone and surgical embolectomy. Although the mortality rate with CBT was lower than historical ST, CBT was noninferior but not superior to ST. However, many patients have absolute or relative contraindications that would prevent them from receiving ST.⁸ Even among those eligible for ST, major bleeding rates have been as high as 6% to 11% with non-negligible rates of ICH (1.2%).⁹ Given the need for alternative effective treatment approaches, CBT emerges as a promising option for CIT patients and may improve outcomes in this high-risk population. Given that current available guidelines do not provide specific recommendations for the treatment of CIT,⁸ our findings may serve as the best evidence to inform and guide treatment strategies while we eagerly await additional prospective studies.

Our study should be interpreted in light of several limitations. The retrospective nature of this study introduces potential biases and limits the ability to establish causality. Prospective studies are needed to validate our findings. Additionally, our CBT cohort sample size was small and we were not able to compare bleeding outcomes in the different treatment strategies due to lack of available data.

Robert S. Zhang, MD¹; Muhammad Haisum Maqsood, MD, MS²; Eugene Yuriditsky, MD³;Peter Zhang, MD⁴; Lindsay Elbaum, MD³; Allison A. Greco, MD⁵; Vikramjit Mukherjee, MD⁵; Radu Postelnicu, MD⁵; Carlos L. Alviar, MD³;Sripal Bangalore, MD, MHA¹

From the ¹Division of Cardiology, Weill Cornell Medicine, New York, New York, USA; ²Department of Cardiology, DeBakey Heart and Vascular Center, Houston Methodist Hospital, Houston, Texas, USA; ³Division of Cardiovascular Medicine, New York University Grossman School of Medicine, New York, New York, USA; ⁴Department of Medicine, New York University, New York, New York, USA; ⁵Division of Pulmonary Critical Care, and Sleep Medicine, New York University, New York, USA.

Disclosures:  Dr. Bangalore serves on advisory boards for Abbott Vascular, Boston Scientific, Biotronik, Amgen, Pfizer, Merck, REATA, Inari, and Truvic. The remaining authors report no financial relationships or conflicts of interest regarding the content herein.

Address for correspondence: Sripal Bangalore, MD, MHA, New York University School of Medicine, New York, NY 10016, USA. Email: sripalbangalore@gmail.com; X: @sripalbangalore