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William T. Kuo, MD, FCCP; Miguel A. De Gregorio, MD, PhD
Author and Funding Information

From the Division of Vascular and Interventional Radiology (Dr Kuo), Stanford University Medical Center; and Minimally Invasive Techniques Research Group (GITMI) (Dr De Gregorio), University of Zaragoza.

CORRESPONDENCE TO: William T. Kuo, MD, FCCP, Division of Vascular and Interventional Radiology, Stanford University Medical Center, 300 Pasteur Dr, H-3651, Stanford, CA 94305-5642; e-mail: wkuo@stanford.edu


FINANCIAL/NONFINANCIAL DISCLOSURES: The authors have reported to CHEST the following conflicts of interest: Dr Kuo is a consultant for Inari Medical, Inc. Dr De Gregorio has reported that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

FUNDING/SUPPORT: This study was funded by the Stanford Division of Vascular and Interventional Radiology.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.


Chest. 2015;148(3):e94-e95. doi:10.1378/chest.15-1247
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Published online
To the Editor:

We appreciate the compliments by Dr Liang and colleagues regarding our article in this issue of CHEST.1 They are quick to note that the PERFECT (Pulmonary Embolism Response to Fragmentation, Embolectomy, and Catheter Thrombolysis) registry lacks a comparison arm, but this was obviously not the aim of our study. We previously acknowledged that registry data need confirmation by randomized trials, but we also emphasized that randomized controlled trials (RCTs) need validation by observational data,1 since RCTs are limited by abundant exclusion criteria.2 Therefore, the strength of the PERFECT registry is data collection on real-world patients with very few exclusion criteria, minimizing sampling error.

Several doubts, some self-contradictory, were expressed that need clarification. The claim that our study is not unique compared with a review3 is mistaken. The cited review3 was limited by mostly single-center retrospective studies and included only patients receiving ultrasound-assisted thrombolysis (USAT). By contrast, our prospective multicenter registry enrolled patients receiving either catheter-directed therapy (CDT) or USAT and revealed no advantage with USAT.1 Our inclusion criteria for massive and submassive pulmonary embolism (PE) were clearly defined along with three exclusion criteria.1 The claim that no subjects were included who failed anticoagulation treatment is untrue. We used CDT as first-line treatment escalation in 97% of patients (98 of 101) who failed anticoagulation treatment and as rescue therapy in three who failed treatment with anticoagulation and systemic tissue plasminogen activator.1 We also reported four deaths due to massive PE and two deaths from submassive PE.1 The observation that echocardiographic interpretations were not quantitative is a valid point. Nevertheless, alleviation of heart strain was validated in the majority by quantitative pulmonary artery pressure reduction1—a reasonable proxy for improvement in right ventricular function.4 Dr Liang and colleagues appear surprised by the absence of major complications and they express uncertainty by stating the “jury is still out” on CDT, but these opinions contradict their own review: “There is increasing evidence that percutaneous CDIs [CDTs] are an essential, effective, and safe alternative to systemic thrombolysis or anticoagulation.”5

The lack of long-term follow-up data was previously addressed,1 and longitudinal outcomes were not the primary aim of our registry. Currently, long-term data following systemic thrombolysis are also lacking,6 and more studies are needed to determine if escalation therapies can reduce the risk of chronic thromboembolic pulmonary hypertension.1 However, we believe it is essential to first understand whether CDT can be safely performed with immediate and short-term benefits—a primary aim of PERFECT.1

Dr Liang and colleagues rightfully emphasize the need for more comparative data; however, they fail to mention the limitations of RCTs2 while ignoring the plethora of existing randomized data.6 The hypothesis that treatment escalation is beneficial has already been proved in multiple trials,6 and a meta-analysis of RCTs involving 2,115 patients with massive or submassive PE6 revealed lower all-cause mortality in those receiving systemic thrombolysis vs anticoagulation alone.6 However, systemic thrombolysis was also associated with a higher risk of major bleeding and hemorrhagic stroke.6 Consequently, Chatterjee and colleagues6 acknowledged future research should focus on the ideal method of thrombolytic administration to maximize clinical benefit and minimize bleeding risk.6 The PERFECT registry helps answer this call by studying the effects of targeted drug delivery using low-dose CDT as an alternative to systemic thrombolysis.

The PERFECT registry is also the first, to our knowledge, to include and safely treat patients who are not candidates for systemic thrombolysis.1 This is significant because 50% of patients with PE have contraindications to systemic thrombolysis,7 so a comparative study (CDT vs systemic thrombolysis) would exclude too many patients and introduce high sampling error. Therefore, RCTs demonstrating treatment efficacy in trial populations will need further validation by effectiveness data from real-world populations. From this standpoint, the pragmatic interpretation of the PERFECT registry is clearer within the broader scope of practice, since we now have stronger real-world evidence1 to support early trial data.4,8 Indeed, to our knowledge, PERFECT is the first multicenter registry revealing the clinical safety and effectiveness of CDT for acute PE in a real-world population.1

Acknowledgments

Role of sponsors: Research staff was used to help participating sites obtain and maintain institutional review board approval and to help gather and organize the incoming data. The sponsor had no role in the design of the study or preparation of the manuscript.

Kuo WT, Banerjee A, Kim PS, et al. Pulmonary embolism response to fragmentation, embolectomy, and catheter thrombolysis (PERFECT): initial results from a prospective multicenter registry. Chest. 2015;148(3):667-673.
 
Nallamothu BK, Hayward RA, Bates ER. Beyond the randomized clinical trial: the role of effectiveness studies in evaluating cardiovascular therapies. Circulation. 2008;118(12):1294-1303. [CrossRef] [PubMed]
 
Engelberger RP, Kucher N. Ultrasound-assisted thrombolysis for acute pulmonary embolism: a systematic review. Eur Heart J. 2014;35(12):758-764. [CrossRef] [PubMed]
 
Kucher N, Boekstegers P, Müller OJ, et al. Randomized, controlled trial of ultrasound-assisted catheter-directed thrombolysis for acute intermediate-risk pulmonary embolism. Circulation. 2014;129(4):479-486. [CrossRef] [PubMed]
 
Avgerinos ED, Chaer RA. Catheter-directed interventions for acute pulmonary embolism. J Vasc Surg. 2015;61(2):559-565. [CrossRef] [PubMed]
 
Chatterjee S, Chakraborty A, Weinberg I, et al. Thrombolysis for pulmonary embolism and risk of all-cause mortality, major bleeding, and intracranial hemorrhage: a meta-analysis. JAMA. 2014;311(23):2414-2421. [CrossRef] [PubMed]
 
Piazza G, Goldhaber SZ. Management of submassive pulmonary embolism. Circulation. 2010;122(11):1124-1129. [CrossRef] [PubMed]
 
Piazza G, Hohlfelder B, Jaff MR, et al. A prospective, single-arm, multicenter trial of the EkoSonic endovascular system with Activase for acute pulmonary embolism. J Am Coll Cardiol Intv. In press.
 

Figures

Tables

References

Kuo WT, Banerjee A, Kim PS, et al. Pulmonary embolism response to fragmentation, embolectomy, and catheter thrombolysis (PERFECT): initial results from a prospective multicenter registry. Chest. 2015;148(3):667-673.
 
Nallamothu BK, Hayward RA, Bates ER. Beyond the randomized clinical trial: the role of effectiveness studies in evaluating cardiovascular therapies. Circulation. 2008;118(12):1294-1303. [CrossRef] [PubMed]
 
Engelberger RP, Kucher N. Ultrasound-assisted thrombolysis for acute pulmonary embolism: a systematic review. Eur Heart J. 2014;35(12):758-764. [CrossRef] [PubMed]
 
Kucher N, Boekstegers P, Müller OJ, et al. Randomized, controlled trial of ultrasound-assisted catheter-directed thrombolysis for acute intermediate-risk pulmonary embolism. Circulation. 2014;129(4):479-486. [CrossRef] [PubMed]
 
Avgerinos ED, Chaer RA. Catheter-directed interventions for acute pulmonary embolism. J Vasc Surg. 2015;61(2):559-565. [CrossRef] [PubMed]
 
Chatterjee S, Chakraborty A, Weinberg I, et al. Thrombolysis for pulmonary embolism and risk of all-cause mortality, major bleeding, and intracranial hemorrhage: a meta-analysis. JAMA. 2014;311(23):2414-2421. [CrossRef] [PubMed]
 
Piazza G, Goldhaber SZ. Management of submassive pulmonary embolism. Circulation. 2010;122(11):1124-1129. [CrossRef] [PubMed]
 
Piazza G, Hohlfelder B, Jaff MR, et al. A prospective, single-arm, multicenter trial of the EkoSonic endovascular system with Activase for acute pulmonary embolism. J Am Coll Cardiol Intv. In press.
 
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