|Year : 2019 | Volume
| Issue : 4 | Page : 248-255
A comparison of pharmacomechanical catheter-directed thrombolysis versus anticoagulation alone in the prevention of postthrombotic syndrome following acute lower limb deep-vein thrombosis
Nikhil Sharma, VS Bedi, Sandeep Agarwal, Ajay Yadav, Ambarish Satwik, Dhruv Agarwal, Apurva Srivastava
Institute of Vascular and Endovascular Sciences, Sir Ganga Ram Hospital, New Delhi, India
|Date of Submission||25-May-2019|
|Date of Acceptance||13-Oct-2019|
|Date of Web Publication||20-Dec-2019|
Dr. Nikhil Sharma
Institute of Vascular and Endovascular Sciences, Sir Ganga Ram Hospital, New Delhi
Source of Support: None, Conflict of Interest: None
Introduction: Postthrombotic syndrome (PTS) occurs in 20%–60% of patients after acute deep-vein thrombosis (DVT) treated with anticoagulation alone. Residual thrombus after DVT leads to ambulatory venous hypertension which consequently causes PTS. Thus, evacuating the clot during DVT itself might prevent PTS – the “Open Vein Hypothesis.” Pharmacomechanical catheter-directed thrombolysis (PCDT) evacuates the thrombus working on this very hypothesis. PCDT is usually performed using specialized devices which are expensive and not easily available in our country. In this study, we describe a method to perform PCDT using a commonly available and inexpensive guiding catheter in an aim to prevent PTS after DVT. Aims and Objectives: This study aimed to evaluate if in acute DVT, our method of PCDT reduces the occurrence of PTS, as compared to anticoagulation alone. Design: This is a prospective, randomized, comparative, cohort study. Study Period: The study was conducted from June 2016 to May 2017 with 1-year follow-up. Materials and Methods: Patients presenting with acute DVT of <3 weeks' duration who met the inclusion criteria were included in this study. They were subsequently randomized to receive either anticoagulation alone or PCDT which was performed in our vascular cath lab using a 7 Fr. guiding catheter to physically macerate and aspirate the clot with simultaneous instillation of fibrinolytic therapy (recombinant tissue plasminogen activator [RT-PA]) in the thrombus.
- The technical success rate was 96%. The mean total dose of RT-PA used was 20.24 mg. The need for venoplasty/stenting was 76%. The rates of major bleeding in the both the groups were similar at 4%
- At 1-year follow-up, the following results were obtained:
The deep vein patency was 84% in the PCDT group as compared to 16 % in anticoagulation only group(controls) (P< 0.001). Deep vein reflux was noted in 16 % of patients in the PCDT group as compared to 52% in the controls (P = 0.016). Furthermore, the PTS (measured by Villalta scale) was seen in 16% in the PCDT group as compared to 48 % in the controls (P = 0.032).
Conclusions: Our method of PCDT is safe and effective as it reduces the occurrence of PTS with preservation of valvular competence and vein patency as compared to anticoagulation alone.
Keywords: Acute deep-vein thrombosis, catheter-directed thrombolysis, guiding catheter, pharmacomechanical, post thrombotic syndrome, recombinant tissue plasminogen activator
|How to cite this article:|
Sharma N, Bedi V S, Agarwal S, Yadav A, Satwik A, Agarwal D, Srivastava A. A comparison of pharmacomechanical catheter-directed thrombolysis versus anticoagulation alone in the prevention of postthrombotic syndrome following acute lower limb deep-vein thrombosis. Indian J Vasc Endovasc Surg 2019;6:248-55
|How to cite this URL:|
Sharma N, Bedi V S, Agarwal S, Yadav A, Satwik A, Agarwal D, Srivastava A. A comparison of pharmacomechanical catheter-directed thrombolysis versus anticoagulation alone in the prevention of postthrombotic syndrome following acute lower limb deep-vein thrombosis. Indian J Vasc Endovasc Surg [serial online] 2019 [cited 2021 Jul 26];6:248-55. Available from: https://www.indjvascsurg.org/text.asp?2019/6/4/248/273594
| Introduction|| |
Despite advances in the prevention of lower limb deep-vein thrombosis (DVT), it still affects 1–4 of 1000 people annually with a rising incidence due to an aging population and constant exposure to DVT risk factors such as hospitalization, contraceptives, pregnancy, and airline travel., Although the treatment of DVT has seen advances with the introduction of newer anticoagulants, prospective studies have still unanimously reported that 20%–60% of patients with DVT will still develop postthrombotic syndrome (PTS) which manifests in few months to years after the index episode. About 5%–10% of patients also develop severe PTS, including intractable venous ulcers which are recalcitrant to therapy. PTS is a syndrome – a constellation of signs and symptoms which is best measured with the Villalta PTS scale which has been shown to be valid, reproducible, and responsive to clinical changes. The scale's components (five symptoms and six signs) are each rated on a 4-point severity scale followed by a score ≥5 denoting PTS.
PTS causes major impairment of quality of life which has been well described by many researchers. In addition, once it develops, its treatment is expensive, ardous, nonrewarding, and not substantiated by evidence-based therapeutic options. Effective management of this condition should, therefore, focus on its prevention rather than treatment.
Anticoagulation therapy for DVT does not actively eliminate thrombus; residual thrombus leads to venous obstruction with subsequent thrombosis-induced venous valvular reflux, ultimately causing ambulatory venous hypertension (AVHTN) which is the sine qua non of PTS. Evacuating the clot during acute DVT itself might thus arrest AVHTN, thereby preventing PTS – this is the basis of the “Open Vein Hypothesis.” Pharmacomechanical catheter-directed thrombolysis (PCDT) evacuates thrombus working on this hypothesis. PCDT is usually performed using specialized devices which are expensive. In this study, we describe a method to perform PCDT using a commonly available and inexpensive guiding catheter and compare its efficacy and safety with anticoagulation alone in an aim to prevent PTS after acute lower limb DVT.
| Materials and Methods|| |
Aims and objectives
To evaluate if in patients with acute iliofemoral DVT, our method of PCDT reduces the occurrence of PTS with preservation of deep-venous valvular competence and deep-vein patency over a 12-month follow-up period, as compared to anticoagulation alone. In addition, to compare between the two treatment arms, namely the resolution of acute DVT symptoms and rates of major and minor adverse events.
This study was conducted in the Institute of Vascular and Endovascular Sciences, Sir Ganga Ram Hospital, New Delhi, India, on a total of fifty patients admitted with a diagnosis of acute iliofemoral DVT from June 2016 to May 2017 with 1-year follow-up.
This was a prospective, randomized, comparative, cohort study.
- Test arm: Patients who receive PCDT + standard DVT therapy
- Control arm: Patients who receive standard DVT therapy alone (anticoagulation).
The eligibility criteria are summarized in [Table 1].
Outcomes were assessed as per definitions provided in [Table 2].
The study was initiated after obtaining approval from the institutional ethics committee, and informed consent was taken from all participants. Post recruitment, all patients were subjected to a disease-specific history and examination which included the recording of the following parameters: self-rating of baseline leg pain score (Likert scale), calf circumference measurement (10 cm below tibial tuberosity), and administration of Villalta's PTS scale. Other relevant baseline blood investigations were sent. Subsequently, DVT was reconfirmed using Doppler ultrasound supplemented by computed tomography venography if deemed necessary.
On the basis of preoperative imaging and intraoperative venography (PCDT group only), each patient was assigned a thrombus score which is calculated as a modified Venous Registry Index score (adapted from Mewissen et al.) The calculation is shown in [Table 3].
After enrollment and baseline assessment, group assignments were determined by a computer-generated number sequence and were contained in sequentially numbered opaque envelopes to ensure blinding.
Statistical testing was conducted with SPSS software Version 25.0 (Statistical Package for the Social Sciences-IBM Corporation, Armonk, New York, USA). For all statistical tests, P < 0.05 was taken to indicate a significant difference.
Anticoagulation and thrombolytic therapy
All patients in both treatment arms were given anticoagulation with intravenous unfractionated heparin or low-molecular-weight heparin in the usual doses. Patients are transitioned on Vitamin K antagonist before discharge to allow overlap therapy. The recommended intensity (target international normalised ratio 2.0–3.0) and duration (3 months or longer) were the same for patients in the two treatment arms.
The thrombolytic agent – recombinant tissue plasminogen activator (rT-PA) – used in this study was Actilyse® (Boehringer Ingelheim). Twenty-milligram Actilyse® vials were used in this study. Actilyse® is reconstituted only with sterile water for injection with a concentration of 1 mg/ml and is used as per product instructions for use.
Pharmacomechanical catheter-directed thrombolysis technique
In the intervention arm, PCDT is performed by our own technique in cath lab under local anesthesia as follows. Initially, a retrievable inferior vena cava (IVC) filter is deployed (jugular/contralateral femoral – if patent). A sheath is then put in place after ultrasonography-guided puncture of the popliteal vein in supine position through which an initial venogram delineates the complete extent of the thrombus which allows the calculation of the thrombus score. Subsequently, a 7 Fr guiding catheter (Cordis, Miami, FL) is advanced into the level of the thrombus and mechanical thrombolysis is then performed by repeatedly macerating the thrombus by physical to-and-fro movement of the guiding catheter under constant fluoroscopic guidance. Boluses of rT-PA (Actilyse®) are given at this stage to hasten lysis. The thrombus fragments are then aspirated from the vein using a large syringe. A final venogram is performed to confirm the degree of thrombolysis in order to determine the final lysis grade (I/II/III). The guiding catheter is exchanged for an infusion catheter (multi sidehole catheter) which is used for the infusion of rT-PA at 0.01 mg/kg/h and a maximum of 35 mg or <1 mg/h. Repeat check venogram(s) is/are performed after a suitable interval to evaluate remnant thrombus burden and if required, we repeat the pharmacomechanical thrombolysis by physical maceration using the technique described above.
Treatment is discontinued when adequate lysis has been achieved or when the 35-mg rT-PA maximum dose is reached or if the patient suffers overt bleeding or alarming complication.
Need for venoplasty/stenting
Balloon angioplasty and/or stenting is used for correction of lesions which are associated with >50% venous diameter narrowing. Self-expandable/dedicated venous stents, sized to the vein's expected diameter (usually 10–16 mm), are implanted [Figure 1].
|Figure 1: Illustration of pharmacomechanical catheter-directed thrombolysis technique used in the intervention arm|
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Patients return for follow-up at 10 days, 30 days, 6 months, 9 months, and 12 months post randomization. The schedule of assessment is summarized in [Table 4].
| Results|| |
A total of fifty eligible patients were enrolled for the study from June 2016 to May 2017 with 12 months of follow-up. The two study arms contained 25 patients each. The study flow diagram is illustrated in [Figure 2].
Baseline characteristics – Demographics, risk factors, and assessment
The demographics, presence of underlying risk factors, and initial assessment of patients randomized to either groups are presented in [Table 5]. Notably, the studied parameters are comparable in both arms with no statistical difference.
Procedural characteristics – Pharmacomechanical catheter-directed thrombolysis group
Retrievable IVC filters were implanted before initiation of the PCDT which were then removed anytime between a week to a maximum of 3 months post procedure. The retrievable filters used commonly were Denali (C.R. Bard, Tempe, AZ, USA) or Celect Jugular/Femoral (Cook, Bloomington, IN, USA). The characteristics of lysis of the PCDT group are presented in [Table 6] and [Figure 3].
|Table 6: Characteristics of lysis - pharmacomechanical catheter-directed thrombolysis group|
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|Figure 3: Characteristics of lysis-pharmacomechanical catheter-directed thrombolysis group|
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Safety outcomes – Adverse events
The two episodes of major bleed in (total – both groups) required blood transfusions (both were perianal bleeds due to preexisting Grade III hemorrhoids – managed conservatively), whereas three episodes of minor bleeding (total – both groups) were puncture-site bleeds managed by compression. No episode of fatal/intracranial bleeding, new-onset renal failure, pulmonary embolism (PE), or mortality occurred in either treatment arms [Table 7].
The symptomatic/clinical success rate was gauged by reduction in mean leg pain scores and mean leg circumference. The PCDT group reported a reduction in both parameters at 10-day follow-up, which was significant for leg pain (P = 0.017) but not significant for leg circumference (P = 0.352). Similar comparison of reduction in mean leg pain and mean leg circumference was again performed at 30 days where both parameters demonstrated statistically significant reduction as compared to the control group (P = 0.002 for leg pain and P < 0.001 for leg circumference) [Figure 4].
The longitudinal trends in deep-vein patency are shown in [Figure 5]. The difference in the two groups was statistically significant with P < 0.05 for all chronological comparisons. At the end of follow-up period of 1 year, deep-vein patency was seen in 84% of PCDT arm and 24% in the control arm (P< 0.001).
Deep vein reflux
The longitudinal trends in deep-vein reflux are presented in [Figure 6]. In the comparison between the two arms, the difference was only borderline statistically significant (P = 0.051) at 1-month and 6-month intervals but assumed significant (P< 0.05) at the 9-month/1-year comparison. At 1-year follow-up, deep-vein reflux was seen in 16% of PCDT arm and 52% in the control arm (P = 0.016).
Villalta score and development of postthrombotic syndrome
The mean Villalta score at 1 year in the control group was 11.65 as compared to 4.24 in the PCDT group, a difference which was statistically significant (P = 0.004). In addition, the PTS developed in only 16% in the PCDT arm compared to 48% in the controls, which is a statistically significant outcome (P = 0.032). Importantly, patients who did not develop PTS had a higher incidence of patent deep veins (73.5%, P < 0.001) with absence of venous reflux (76.4%, P = 0.03) at 1-year follow-up [Figure 7].
|Figure 7: Comparison of postthrombotic syndrome and Villalta score at 1 year|
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| Discussion|| |
The results presented above have demonstrated that our method of PCDT reduces the occurrence of PTS with preservation of deep-vein valvular competence and patency as compared to anticoagulation alone (it is efficacious). PCDT has also shown to be innocuous and has been relatively devoid of significant complications (it is safe). Our findings support the “Open Vein Hypothesis” which can be leveraged to prevent PTS which is otherwise a recalcitrant disease once it develops [Table 8].
The concept of using thrombolysis for DVT started with the use of systemic thrombolysis which was soon supplanted by CDT, which resulted in reduced lytic drug requirement with the resultant benefit in the reduction of bleeding events. The CaVenT study was a multicentric randomized controlled trial which utilized CDT for PTS prevention in acute DVT. At an impressive 5-year follow-up, PTS developed in 43% in the CDT group compared with 71% in the control group (P< 0.0001), corresponding to an absolute risk reduction of 28% and a number needed to treat of 4.
The success of CDT ushered in an era of PCDT in which commercially available devices/catheters were used for effecting lysis. The TORPEDO trial compared PCDT using the Angiojet (Boston Scientific, Marlborough, MA, USA) and Trellis (Medtronic, Minneapolis, MN, USA) devices with anticoagulation alone in PTS prevention post-DVT. PTS developed in 3.4% of the PCDT group compared to 27.2% in the control arm (P< 0.001). However the results from the multicentric ATTRACT study were a disappointment. PCDT was not found to reduce PTS compared to anticoagulation alone (PTS 46.7% for PCDT vs. 48.2% for controls, P = 0.56) Despite this, if only the IFDVT cohort was chosen and the yardstick was modified to moderate/severe PTS (Villalta score >10), the results would have favored intervention versus anticoagulation alone. An overall significant 10% reduction was seen in moderate/severe PTS in this subgroup analysis (18.4% vs. 28.2% in PCDT vs. controls). Thus, all is not lost and almost a decade of work involving 700 patients has indeed been fruitful.
The limitations of PCDT devices are that they are expensive and have limited availability, especially in our country. Consequently, to circumvent these impediments, we have developed our own technique as described above. In this study, we have found that PTS was significantly reduced in the PCDT group compared to controls at 12-month follow-up (16% vs. 48%, P = 0.032). Similar reduction in PTS was reported by the CaVenT (28% reduction) and TORPEDO (23.8%) investigators. In addition, at 1-year follow-up, the mean Villalta score was statistically significantly lower in the PCDT group as compared to controls (4.24 vs. 11.64, P = 0.004).
The deep-vein patency improved statistically significantly throughout the follow-up and was 84% in the PCDT group versus 24% in the control group at 1-year follow-up (60% gain in patency, P < 0.001). Srinivas et al. reported a 57% gain in patency at 6 months using PCDT. The deep-vein reflux was also significantly reduced in the PCDT group as compared to controls at the end of 1 year – 16% in PCDT group versus 52% in controls (36% reduction in reflux, P = 0.016). Similarly, Laiho et al. reported a 29% reduction in reflux with the use of PCDT as compared to anticoagulation. In our study, we found that patients who did not develop PTS had a higher incidence of patent deep veins (73.5%, P < 0.001) with absence of venous reflux (76.4%, P = 0.03) at 1-year follow-up. CAVENT reported similar results –those without PTS at 2 years had patent veins (77.3%, P = 0.002) with absence of deep-vein reflux (63%, P < 0.001). The above findings lend substantial statistical support to the “Open Vein Hypothesis” and also demonstrate its successful utilization by our group to prevent PTS.
The technical success rate (TSR) (Grade II or III lysis) was 96% in our study. The Angiojet PEARL registry also reported a TSR of 96%. The need for venoplasty/stenting in our series was 76%. Similarly, the ATTRACT trial had a 88% need for additional stenting/venoplasty, while the TORPEDO group reported its use in 75.5%. This high percentage of need for venoplasty/stenting underscores a hitherto unexplored aspect of PCDT – it unmasks precursor lesions which can be treated leading to reduction in the rates of recurrent DVT. This advantage of PCDT is unmatched by the use of anticoagulation alone. Retrievable IVC filters were used in all PCDT cases to prevent iatrogenic PE during the procedure on the basis of results published in the FILTER-PEVI trial, which demonstrated an eightfold reduction in PE with IVC filter use during endovascular lysis.
The mean rT-PA used was 20.24 mg, which is similar to 20 mg reported by ATTRACT investigators. This is much lower than doses used during systemic thrombolysis and translates into lower cost and reduced bleeding episodes. The rate of major bleeding in both groups was 4%. Minor bleeding was noted in 8% in the PCDT group and 4% in the anticoagulation group, a difference which was not statistically significant (P = 1.00). Similar rates were reported by Kim et al. (4% major bleeding) where Angiojet was used for PCDT. Furthermore, there were no cases of new-onset renal failure or PE in our study, possibly due to the routine implantation of IVC filters. Similar nil incidence of renal failure and PE were reported by Huang et al. This highlights the fact that despite the use of thrombolytic agents, our method of PCDT is relatively devoid of complications.
However, few limitations are present in our study which deserve mention. First, the sample size was small which could have introduced bias. Second, a longer follow-up would have been more desirable as PTS is a chronic disease. Third, certain scores in our study (Villalta score/Thrombus burden/Likert scale/Duplex criteria for patency/reflux) and consequently some outcomes (PTS) rely on subjective responses of both the clinician and the patient. In order to better elucidate the role of PCDT in PTS prevention, further research is required and reports from ongoing trials (Dutch CAVA trial) are awaited.
| Conclusions|| |
PTS causes major morbidity and is a socioeconomic burden as it affects a relatively younger and economically productive population. The current management of PTS is far from satisfactory – prompt thrombus clearance using PCDT offers the best attempt to prevent its development. Owing to the high cost of the current PCDT devices, we have utilized a commonly available guiding catheter to macerate acute thrombus along with localized infusion of thrombolytic agent to hasten clot removal.
We have found that our method of PCDT is safe and leads to excellent thrombus clearance with significant reduction in leg pain and swelling, improved venous patency, reduced valvular reflux, and, most importantly, reduction in PTS. In addition, during this process, the underlying venous lesions may get unmasked which can be treated during the same procedure by venoplasty/stenting. Our findings support the concept of “Open Vein Hypothesis” which can be utilized to prevent PTS by this method in low-resource settings such as ours. We recommend the use of PCDT in properly selected patients and hope that the current study will pave the way for future research, thus elucidating yet undiscovered facades of this disease, thereby promoting its prevention and mitigating its detrimental effects.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8]