Patency rate and quality of life after ultrasound-accelerated catheter-directed thrombolysis for deep vein thrombosis

Abstract

Purpose

Studies on ultrasound-accelerated, catheter-directed thrombolysis of acute deep vein thrombosis emphasize good patency rates and low complication rates. Therefore, we analyzed quality of life besides technical success and patency in our patients after ultrasound-accelerated, catheter-directed thrombolysis.

Methods

Between 2009 and 2014, 42 patients suffering from iliofemoral deep vein thrombosis received ultrasound-accelerated, catheter-directed thrombolysis. Follow-up included clinical exanimation and ultrasound. Thirty patients (36 interventions), mean age 41.3 years (range 19–71 years), 56.6% women (17/30), completed the surveys. Five different scores were used to assess the quality of life and symptoms of postthrombotic syndrome: SF36, Euro-QOL 5D, PDI, VEINES-QOL/Sym, and the Villalta score.

Results

Mean therapy duration of ultrasound-accelerated, catheter-directed thrombolysis was 76.4 h and therapeutic success could be reported in 80.5% (29/36). Successful ultrasound-accelerated, catheter-directed thrombolysis was followed by stent angioplasty in 58.3% (21/36) procedures. Overall complication rate was 19.44%, mainly formed by minor bleedings. Mean follow-up was 38.5 months. The primary patency rate was 63.8%, the assisted-primary and the secondary patency rate were 80.5%. We observed an improved quality of life in our patients’ cohort compared to patients suffering from postthrombotic syndrome.

Conclusion

Although ultrasound-accelerated, catheter-directed thrombolysis is feasible with good patency rates, further prospective randomized trials are necessary to evaluate the value of thrombus removal in iliofemoral deep vein thrombosis in comparison to conservative treatment.

Keywords

Deep vein thrombosis endovenous technique postthrombotic syndrome quality of life assessment thrombolysis

Introduction

Venous thromboembolism is the third most common cardiovascular disease after coronary heart disease and stroke, with an estimated incidence of 50.4 primary deep vein thrombosis (DVT) per 100,000 persons-years in western populations. Patients with acute DVT are treated by anticoagulation, compression therapy, and mobilization.^1,2 This standard triple therapy for DVT decreases mortality by preventing life-threatening pulmonary embolism and thrombus propagation. The clinical benefit of compression stockings regarding its efficiency for the prevention of postthrombotic syndrome (PTS) is still under debate.^3–5 Still some authors emphasize the value of consequent compression therapy in selected patients to prevent PTS.^6,7 However, this therapy offers no direct thrombolytic effect and the recanalization of the involved veins and the preservation of valve function depend on the individual fribinolytic system. The PTS as the long-term sequela of DVT is caused by venous obstruction or insufficiency of the deep venous system.^8,9 After iliofemoral DVT, only 30% of iliac veins recanalize with standard therapy. Forty-four percent of patients with iliofemoral DVT suffer from venous claudication, and 15% of these patients develop venous ulcers within five years after DVT.^10,11 Depending on the extent and localization of DVT, 20–83% of patients develop PTS. Compared to lower leg DVT, iliofemoral DVT is associated with a 50% increased risk of developing PTS.^12,13 Furthermore, Singh and Masuda¹⁴ reported that the combination of obstruction and reflux, rather than either one of these factors, significantly increases the risk of PTS.¹⁴ Meissner et al.¹⁵ demonstrated that valve function is more likely retained after early clot lysis. Within the last decade, CDT as treatment option of acute DVT has gained attention due to good patency rates, low complication rates, and a reduced incidence of PTS.^16,17 Furthermore, a reduced frequency of employee absenteeism was recognizable in patients treated with CDT.¹⁸ Although promising, most evidence on catheter-directed thrombolysis (CDT) is derived from case series¹⁹ and not from randomized clinical trials.^20–23 Enden et al.²² presented the first long-term results of a prospective randomized trial supporting the CDT in DVT. Although the catheter-directed venous thrombolysis in acute iliofemoral vein thrombosis (CAVENT) trial was able to demonstrate a statistically significant reduced incidence of PTS after CDT compared to conservative treatment, no improved quality of life (QOL) could be assessed after a five-year follow-up.²⁴ While the results of the acute venous thrombosis: thrombus removal with adjunctive catheter-directed thrombolysis (ATTRACT) as well as the ongoing catheter versus anticoagulation alone for acute primary (Ilio)femoral DVT (CAVA) trial are pending, no prospective randomized trial has shown improved QOL after CDT.

Regarding technical aspects of CDT, in vitro studies revealed enhanced thrombolysis and increased uptake of thrombolytic drugs into the thrombus by ultrasound.^25,26 Furthermore, Mewissen et al.²⁷ showed a higher complete clot lysis rate of ultrasound-accelerated (UA) CDT compared to standard CDT without increasing the incidence of bleeding complications. On the other hand, Engelberger et al.²⁸ compared ultrasound-accelerated, catheter-directed thrombolysis (UACDT) with standard CDT in 48 patients with a fixed dose regimen (20 mg recombinant-tissue plasminogen activator (r-tPA) over 15 h) and revealed no advantage for the additional ultrasound. Important limitations of this study are the shortened time of CDT and the small patient group. In contrast, Broholm et al.²⁹ were able to demonstrate a low incidence of PTS after successful treatment with conventional CDT without ultrasound enhancement.

While the results of prospective randomized trials concerning the effectiveness of CDT are still pending, we analyzed our results of UACDT with focus on PTS and QOL.

Methods

Patients

The Ethics Committee of the University Hospital Aachen approved this study (Number: EK 248/15). Patients’ data were assessed retrospectively during the time of the survey, starting in August 2015. DVT was detected by ultrasound and computed tomography or magnetic resonance angiography. Exclusion criteria were life expectancy less than six months, DVT older than 21 days, pregnancy, and active cancerous disease with metastasis or surgical treatment within the last four weeks. No patients have been excluded after receiving UACDT. All cases of acute DVT with symptoms lasting less than 21 days, involving the iliofemoral segment or the inferior caval vein were included. Besides UACDT, all patients received the standard treatment for DVT including anticoagulation, compression, and mobilization. Follow-up examination was performed two weeks after the CDT and every six months afterward. Follow-up included ultrasound examination of the affected veins as well as clinical examination. The QOL assessment, including all questionnaires as well as the Villalta score, was completed from August to November 2015. All patients without successful use of UACDT received conservative treatment after DVT including compression stockings, mobilization, and anticoagulation. Anticoagulation was performed by use of Phenprocoumon (Meda GmbH Bad Homburg, Germany) and targeted international normalized ratio was 2–3. Twelve patients have been excluded as they were not willing to participate and did not complete the survey.

UACDT

UACDT was performed using the EKOS Endowave® system (EKOS Corporation, Bothell, WA, USA). In this device, a high-frequency, low-power US energy is combined with a targeted drug delivery system. The insertion of the 5.2 french multilumen intelligent drug delivery catheter system, which was always performed in an interventional radiology suite, used a standard 0.035 hydrophilic guide wire (Terumo Cooperation, Shibuya-ku, Tokyo, Japan) and a 6 french sheath. The available length of the catheters’ “infusion segments” ranges from 6 to 50 cm. After ultrasound-guided puncture of the popliteal, femoral, or the jugular vein positioning of the catheter over the guide wire was performed using X-ray guidance. The end of the “infusion segments” should reach the proximal thrombus. Afterward the guide wire will be replaced by a microsonic core, which contains a series of US transducer elements (2 MHz, 0.45 W), distributed approximately 1.0 cm apart along its leading tip to deliver US energy radially along the coaxial infusion zone.

Thrombolysis

At the beginning of the lysis, r-tPA (5.0 mg, Boehringer Ingelheim Pharma Viersen, Germany) was given as single bolus into the lysis catheter, followed by a slow infusion through the side-hole-delivery infusion catheter. The flow rate of r-tPA was 1.0 mg/h. Coolant infusion was given via the central lumen of the catheter with a rate of 35 ml/h. Additionally, ultrasound energy was delivered through the central core wire. Accompanying intravenous heparin infusion was applied continuously during the lysis therapy. If both legs have been involved, the same procedure was applied for each side. Monitoring was performed by measuring the activated partial thromboplastin time with aimed elevation of 1.5–2.5 times and fibrinogen. Dosage of r-tPA was reduced if decrease of fibrinogen below 100 mg/dl was observed. Follow-up venograms have been performed every 24 h to control the success of treatment. UACDT was terminated after 72 h, yet some patients received longer lysis treatment-based residual thrombus. Success was evaluated based on the comparison of the venograms and the decreasing thrombus burden. If angiography reveals residual stenosis after UACDT, stenting was performed at the end of the UACDT. After successful thrombolysis, patency of the treated veins was confirmed by ultrasound examination before the patient left the hospital. Follow-up was performed according to the international guidelines of DVT treatment.³⁰ (See figure 1 (A-D) as illustration for the procedure)

Figure 1.

Thrombolysis using UACDT with venography before (a) the treatment, after 24 h (b) and 48 h (c), as well as after successful UACDT supplemented by stent angioplasty (d). UACDT: ultrasound-accelerated, catheter-directed thrombolysis.

QOL scores

Five different scores were used to assess patients’ disease-specific and general QOL after the use of UACDT as treatment of DVT. All patients received the surveys from September to December 2015.

SF36

The SF-36 is a multidimensional survey, which can assess subjective, health-related aspects of the QOL composed by 36 questions. The survey is a generic and psychometric tool for patients’ self-assessment, which is used in 12 countries.³¹ The questionnaire is characterized by its international comparability. After T-transformation and summary of the subscales to the total scale values, the mental component summary score (MCS) and physical component summary score (PCS) can be calculated.

EuroQOL-5D

This health-related QOL score is an international used tool composed by five questions.³² The EuroQOL score had been tested psychometrically and the results can be compared internationally. Due to a low specificity it should be applied together with further scoring systems. QOL assessment is separated in five different categories (mobility, self-sufficiency, daily activity, pain, and depression/anxiety).

Pain disability index (PDI)

The PDI can be used to assess pain-related restrictions in different fields of activity. This survey can be applied during and after a therapy to evaluate its effectiveness regarding the ability to reduce pain.

Venous insufficiency epidemiologic and economic study of quality of life (VEINES-QOL/Sym)

The VEINES-QOL/Sym questionnaire is a disease-specific tool, which can be used for self-assessment regarding QOL and symptoms due to DVT. By answering 26 items, scores for venous symptoms and venous-specific QOL can be calculated.³³ It is characterized by a favorable comparability, even if the patients’ cohorts differ regarding the comorbidities.

Villalta score

The Villalta score is a tool for identification and follow-up evaluation of PTS.³⁴ Subjective symptoms and objective clinical signs of PTS are assessed using a four-staged scale.

0–4: No PTS;

5–9: PTS;

10–14: Moderate PTS;

15–33: Severe PTS.

Definitions

Thrombolysis success

The success of the UACDT was evaluated daily during treatment using venography of the affected vessels. The thrombus score was calculated as described previously by Mewissen et al.²⁷ and Strijkers et al.³⁵

Complete clot lysis was defined as > 90% lysis (restored patency).

Partial clot lysis was defined as 50–90% lysis (restored patency).

The success was evaluated using the final venography before admission.

Patency

Patency was evaluated within 24 h after successful UACDT by ultrasound and clinical examination. Follow-up included examinations after two weeks, six, and 12 months and ultrasound control every year of the follow-up. During these examinations, the iliac veins of the affected side were evaluated regarding patency and, if present, the stent geometry was assessed.

Bleeding

Major bleeding requires a fall in hemoglobin of ≥2 g/dl, associated with the indication for blood transfusions. Organ-related bleeding was also classified as major bleeding. Puncture site bleeding was classified as minor bleeding complication.

Statistics

Mean, standard deviation, and range are used to present continuous data. Frequencies and percentages are given for categorical data. SPSS Statistics (version 23.0; IBM Corporation, Somers, NY, USA) was used for statistical analysis. Multiple testing was not applied because of the small number of patients included in the study and because we were not able to find statistically significant differences. A Kaplan–Meier survival analysis was used to calculate patency rates. Standard error of the mean values of >10% were discarded as being unreliable and are not reported. A p-value of < 0.05 was considered statistically significant. All graphs have been created using MedCalc® (Version 15.8 by MedCalc Software bvba, Ostend, Belgium, and IBM® SpSS® Statistics Version 22, International Business Machines Corp).

Results

Population

Forty-two patients were treated by UACDT due to DVT between 2009 and 2014. Thirty patients, mean age 41.3 years (range 19–71 years), 56.6% women (17/30), completed the surveys from September to December 2015. None of the patients, who were excluded, died. Furthermore, their baseline characteristics were not differing from those patients who were analyzed in our study.

Mean body mass index was 26.13 kg/m² (standard deviation (SD): 3.86; range 19–38) and 73.3% (22/30) of the patients suffered for the first time from DVT.

Localization

The common iliac vein was involved in 43.33% (13/30), and the external iliac vein was involved in 20% (6/30) of the cases. The lower vena cava was involved in 36.67% (11/30) of the patients. Seventy percent (21/30) of the patients were suffering from a left-sided, 30% (9/30) and from a right-sided DVT. In 10% of the cases (3/30), bilateral DVT was treated. Furthermore, three patients were suffering from recurrent DVT within three months after the first UACDT and received successful repeat of the UACDT. Overall, 30 patients received 36 interventions in this study.

Comorbidities

Twenty percent (6/30) of the patients were suffering from a May–Thurner syndrome, and 13.3% (4/30) were suffering from thrombophilia, in particular factor-V disease mutation. The following malignant diseases could be found in the patients’ cohort: seminoma, esophagus cancer, and Wilms’ tumor. Assessing the cardiovascular risk of the patients, 10% (3/30) were suffering from arterial hypertension, 6.6% (2/30) were suffering from coronary heart disease, and 3.3% (1/30) were suffering from peripheral artery disease. Further details concerning comorbidities can be found in Table 1.

Table 1.

Overview of procoagulant comorbidities in the patients’ cohort.

Diagnosis	n	%
May–Thurner syndrome	6	20
Malignant disease	3	10
Status postpartum	2	6.67
Immobilization	1	3.33
Thrombophilia	4	13.33
Smoking	5	16.67
Oral contraceptives	1	3.33
Pelvic bone associated compression	1	3.33

Therapy

Mean therapy duration was 76.38 h (SD 21.3 h, range 24–120 h). All patients have been treated with r-tPA (dosage 1 mg/h). The standard vascular access via the popliteal vein was successful in 69.4% (25/36) of the cases. In 27.7% (10/36) of the cases, the femoral vein was used as access vessel. A reduction of more than 90% of the thrombus was reached by UACDT in 55.5% (20/36); a 50–90% reduction was possible in 25% (9/36) of the treated vessels. Summarized, a therapeutic success could be reported in 80.5% (29/36). A reduction of the thrombus up to 50% was achieved in 5.5% (2/36), 13.8% (5/36) of the procedures were not successful. Totally, 19.5% (7/36) procedures did not succeed following the criteria mentioned above.

In 61.1% (22/36) additional interventions have been carried out after UACDT. In 58.3% (21/36) an angioplasty combined with the implantation of stents was performed. One patient received completion of the venous recanalization by the use of a thrombectomy catheter. Stent angioplasty was mainly performed in the common iliac vein (n = 14), and the inferior vena cava was involved in two cases. No complications occurred during these supplementary procedures. All details for the additional procedures can be found in Table 2.

Table 2.

Overview of the additional procedures after CDT.

Additional procedure	n	%
Angioplasty EIV	2	5.56
Stent angioplasty EIV	3	8.33
Stent angioplasty CIV	14	38.89
Stent angioplasty ICV	2	5.56
Thrombectomy catheter	1	2.78

CDT: catheter-directed thrombolysis; CIV: common iliac vein; EIV: external iliac vein; ICV: inferior caval vein.

Complications

Overall complication rate was 19.44% (7/36). Minor bleedings at the puncture side occurred in 16.6% (6/36). Furthermore, one case of fibrinogen decrease without any therapeutical consequence could be assessed. No case of major bleeding, pulmonary embolism, or catheter-related complication could be assessed.

Patency and follow-up

The patency was 63.8% (23/36), the assisted-primary patency was 80.5% (29/36), including venous stent angioplasty after the UACDT. The secondary patency was 80.5% (29/36), as all cases of recurrent DVT could successfully be treated with UACDT and venous stent angioplasty. The mean follow-up was 38.5 months (SD 11.3 months, range 11 till 114 months). Details presented as Kaplan–Meier curve can be found in Figure 2.

Figure 2.

Kaplan–Meier curve showing the time to loss of patency (primary and secondary patency) after successful UACDT. UACDT: ultrasound-accelerated, catheter-directed thrombolysis.

QOL assessment

The QOL assessment was performed after a mean follow-up of 38.5 months.

During the evaluation, no potential correlation between the time since the UACDT and QOL values assessed was recognizable.

SF-36

The mental health correlated scale (MCS) and physical health correlated scale (PCS) have been calculated. In total, a mean value of MCS for all patients of 47.4 (SD 9.01, range 22.23–60.55) and a mean value of PCS of 49.58 (SD 8.2, range 25.1–60.02) could be assessed. See Table 3 for an overview of MCS and PCS in different subgroups of the study. No significant differences regarding the outcome in the subgroups successful or no successful treatment was recognizable (p-value PCS: 0.34, p-value MCS: 0.51).

Table 3.

Mean values for MCS and PCS for different subgroups of the study.

Subgroups	MCS (mean, SD, (range))	PCS (mean, SD, (range))
All	48.73 (11.6 (22.2–60.55))	46.61 (9.4 (25.02–60.4))
May–Thurner syndrome	49.54 (11.4 (20.9–51.3))	46.16 (10.09 (19.8–60.5))
ASA 3 classification	49.78 (9.3 (19.2–59.3))	42.06 [9.7 (19.5–59.3))
Severe comorbidity	50.09 (8.7 (17.9–60.2))	47.36 (11.8 (18.7–58.3))

ASA: American Society of Anesthesiology; MCS: mental component summary score; PCS: physical component summary score; SD: standard deviation.

EuroQOL-5D

The transformation of the calculation for this QOL score is not available yet. Hence the frequencies of the answers were demonstrated separated by the category therapeutic success or no success. The results can be found in Table 4. A higher percentage indicates a higher level of the analyzed characteristic in the mentioned subgroup.

Table 4.

Assessment of the EuroQOL-5D score of the two subgroups with demonstration of all categories.

EuroQOL-5D	Successful UACDT (%)	Nonsuccessful UACDT (%)
Mobility	73.9	71.4
Self-sufficiency	65.2	57.1
Daily activity	65.2	57.1
Pain	43.5	42.8
Depression/anxiety	60.8	71.4

UACDT: ultrasound-accelerated, catheter-directed thrombolysis.

PDI

The analysis of the PDI showed different, but not significant differing pain levels regarding different areas of life in the group with successful treatment versus nonsuccessful treatment: Mean value was 2.14 (SD 2.01, range 0–8.57). A higher value indicates a higher level of pain-related daily limitations (p-value 0.41).

VEINES-QOL/Sym

After calculation and T-transformation of the VEINES-Sym and VEINES-QOL score, values of 50.25 and 50.2 for VEINES-Sym/QOL could be assessed (see Table 5 for more details). No significant differences regarding the outcome in the subgroups successful or no successful treatment were recognizable either.

Table 5.

Assessment of the SF-36 and the VEINES-Sym/QOL questionnaire separated by the group’s successful and nonsuccessful treatment.

	Successful UACDT (mean + SD + range)	Nonsuccessful of UACDT (mean + SD + range)	p-value
SF 36
MCS	45.89 (11.6, 22.23–60.55)	48.98 (7.03, 43.63–58.77)	0.34
PCS	47.98 (9.47, 25.14–60.02)	51.19 (7.2, 40.78–60.02)	0.32
VEINES-Sym	49.8 (10.0, 27.7–65.0)	50.7 (8.3, 28.9–65.0)	0.76
VEINES-QOL	49.8 (10.6, 34.3–74.5)	50.6 (8.6, 38.8–62.9)	0.61

MCS: mental component summary score; PCS: physical component summary score; SD: standard deviation; UACDT: ultrasound-accelerated, catheter-directed thrombolysis; VEINES-QOL: Venous insufficiency epidemiologic and economic study of quality of life.

Villalta score

Following the Villalta score, nine patients are suffering from PTS, eight of these classified as moderate or low PTS. This means 30% of the patients are suffering from mild PTS following the Villalta classification. Seventy percent (21/30) of the patients showed no clinical signs of PTS (see Table 6 for more details).

Table 6.

Assessment of the Villalta score of the subgroups successful UACDT and nonsuccessful UACDT.

PTS	Successful UACDT	Nonsuccessful UACDT	Total
No	16	5	21
Light	3	1	4
Moderate	3	1	4
Severe	1	0	1
Yes	7	2	9
No	16	5	21

PTS: postthrombotic syndrome; UACDT: ultrasound-accelerated, catheter-directed thrombolysis.

Discussion

The present study underlines the safety and patency of UACDT using the EKOS® system in case of DVT. UACDT reduces the frequency of PTS after DVT involving the femoral and iliac veins by creating a nonoccluded venous outflow. Yet no increased QOL was verifiable while using different questionnaires.

Beneath a short time frame to evaluate the clinical symptom of PTS after acute DVT, the small size of the cohort may be a potential explanation for these findings. Regarding the patency rate of the presented cohort, we observed a primary success for 80.5% of the interventions, which is comparable to further studies.³⁶

The complication rate seems to be high with 19.44% of all procedures. Yet all of these complications are formed by minor problems without necessity of treatment, namely puncture site bleedings (n=8) without any need of blood transfusions and moderately lowered fibrinogen without need of substitution in one case. Summarizing, no severe clinical complication could be detected in this cohort of patients.

The rate of additional stent angioplasty after UACDT was 61.1% in the presented cohort. Compared to the results of Engelberger et al.,²⁸ who mentioned a rate of additional stent angioplasty of 80%, the mean intervention time in our study was significantly longer (76.38 h versus 15 h). In contrast to Engelberger et al., UACDT treatment duration for these patients was longer in order to remove as much thrombus as possible and avoid extended stenting.

Concerning the QOL assessment, our follow-up of 38 months is comparable to the CAVENT trial, one of the most important trials regarding the value of CDT for acute DVT treatment.²⁴ Additionally, relevant information about patients’ comorbidities with potential influence on the therapeutical success as well as the QOL assessment after interventional treatment have been demonstrated and analyzed. Comparing the results of these assessments, all patients showed normal values within the different scoring systems, indicating a normal QOL. Significant differences could be neither assessed in the disease-specific VEINES-QOL and VEINES-Sym questionnaire nor in the non-disease-specific SF36 survey. Regarding the Villalta score, only few cases of moderate PTS could be observed in the patients’ cohort. These results are comparable to the findings of the CAVENT trial: Here the five-year results showed a persistent and increased clinical benefit, following the use of CDT. Nevertheless, no improved QOL was recognizable in the validation group.²⁴

Still we are not able to evaluate, if an improved QOL may be the result of UACDT compared to conservative treatment as therapeutical strategy in case of acute DVT. We think it is important to mention the fact that the follow-up period of all available studies, which we try to evaluate the benefit of UACDT to prevent PTS, is short regarding the normal course of PTS.

Comparing our findings with further studies dealing with QOL after conservative treatment of DVT, an improved QOL of our patients’ cohort was remarkable. Ashrani et al.³⁷ evaluated the QOL after DVT and following venous obstruction. While using the SF36 questionnaire, they were able to assess a PCS of 38.6 if patients are suffering from venous outflow obstruction. This value is considerably lower than the value of 47.9 evaluated after successful UACDT in our cohort. Van Korlaar et al.³⁸ used the SF-36 questionnaire while evaluating the QOL of patients suffering from PTS. In this study, which is comparable to our study regarding patients’ age and group size, a considerably lower value of 41.0 and 43.8 for the PCS, respectively, the MCS compared with the present cohort of patients can be seen (see figure 3 for all details).

Figure 3.

Comparison of the S36 and VEINES-Sym/QOL assessment of the present study cohort with similar studies of the last years dealing with QOL assessment in patients suffering from postthrombotic syndrome. UACDT: ultrasound-accelerated, catheter-directed thrombolysis; VEINES-QOL: Venous insufficiency epidemiologic and economic study of quality of life.

In their study, Kahn et al.³⁹ and Roberts et al.⁴⁰ were able to show a significantly lower QOL using the VEINES-Sym/VEINES-QOL questionnaire for patients suffering from PTS symptoms compared to patients with a history of DVT without these symptoms. Regarding the SF36 questionnaire, no differences between the two subgroups could be assessed in this study.

While a direct comparison of the present examination with the prospective, randomized multicenter CAVENT study should be avoided, similar results are recognizable: Minor bleedings are the most important complications after UACDT and the success rate is appropriate. Even if the QOL, objectified by the mentioned queries, is good after successful therapy and comparable to the normal population, a significant increased QOL compared to patients without successful venous recanalization by use of UACDT after acute DVT was not verifiable.

Different limitations with impact on the results of the study have to be mentioned: The retrospective character of the study is a consistent restriction of the scientific value; furthermore, the small number of patients included (n = 30) influenced the findings. Additionally, the missing baseline QOL assessment reduces the validity of the surveys. This may be an explanation for the nonimproved QOL after successful treatment. Hence the results of the QOL assessment has to be reflected critically regarding its transferability.

Conclusion

UACDT using EKOS® is safe, feasible, and shows good patency rates. Stent angioplasty of the iliac veins is commonly necessary after UACDT but not associated with an increased complication rate. Although UACDT is feasible with good patency rates, further prospective randomized long-term trials are necessary to evaluate the value of thrombus removal in iliofemoral DVT in comparison to conservative treatment considering QOL improvement.

Footnotes

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

Ethical approval

The Ethics Committee of the University Hospital Aachen approved this study (Number: EK 248/15).

Guarantor

JG.

Contributorship

AG: statistics, data collection, writing, revision. RG: statistics, data collection, survey evaluation. MEB: data collection, survey evaluation. PB: Critical revision. AK: statistics, revision. CW: revision. HJ: revision. JG: writing, revision.

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