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WASHINGTON – On the basis of a large randomized trial called ATTRACT, many clinicians have concluded that pharmacomechanical intervention is ineffective for preventing postthrombotic syndrome (PTS) in patients with deep venous thrombosis (DVT). But weaknesses in the study design challenge this conclusion, according to several experts in a DVT symposium at the 2018 Cardiovascular Research Technologies (CRT) meeting.
“The diagnosis and evaluation of DVT must be performed with IVUS [intravascular ultrasound], not with venography,” said Peter A. Soukas, MD, director of vascular medicine at Miriam Hospital in Providence, R.I. “You cannot know whether you successfully treated the clot if you cannot see it.”
“There were lots of limitations to that study. Here are some,” said Dr. Soukas, who then listed on a list of several considerations, including the fact that venograms – rather than IVUS, which Dr. Soukas labeled the “current gold standard” – were taken to evaluate procedure success. Another was that only half of patients had a moderate to severe DVT based on a Villalta score.
“If you look at the subgroup with a Villalta score of 10 or greater, the benefit [of pharmacomechanical intervention] was statistically significant,” he said.
In addition, the study enrolled a substantial number of patients with femoral-popliteal DVTs even though iliofemoral DVTs pose the greatest risk of postthrombotic syndrome. Dr. Soukas suggested these would have been a more appropriate focus of a study exploring the benefits of an intervention.
The limitations of the ATTRACT trial, which was conceived more than 5 years ago, have arisen primarily from advances in the field rather than problems with the design, Dr. Soukas explained. IVUS was not the preferred method for deep vein thrombosis evaluation then as it is now, and there have been several advances in current models of pharmacomechanical devices, which involve catheter-directed delivery of fibrinolytic therapy into the thrombus along with mechanical destruction of the clot.
Although further steps beyond clot lysis, such as stenting, were encouraged in ATTRACT to maintain venous patency, Dr. Soukas questioned whether these were employed sufficiently. For example, the rate of stenting in the experimental arm was 28%, a rate that “is not what we currently do” for patients at high risk of PTS, Dr. Soukas said.
In ATTRACT, major bleeding events were significantly higher in the experimental group (1.7% vs. 0.3%; P = .049). The authors cited this finding when they concluded that the experimental intervention was ineffective. Dr. Soukas acknowledged that bleeding risk is an important factor to consider, but he also emphasized the serious risks for failing to treat patients at high risk for PTS.
“PTS is devastating for patients, both functionally and economically,” Dr. Soukas said. He called the morbidity of deep vein thrombosis “staggering,” with in-hospital mortality in some series exceeding 10% and a risk of late development of postthrombotic syndrome persisting for up to 5 years. For those with proximal iliofemoral DVT, the PTS rate can reach 90%, about 15% of which can develop claudication with ulcerations, according to Dr. Soukas.
A large trial that was published in a prominent journal, ATTRACT has the potential to dissuade clinicians from considering pharmacomechanical intervention in high-risk patients who could benefit, Dr. Soukas said. Others speaking during the same symposium about advances in this field, such as John Fritz Angle, MD, director of the division of vascular and interventional radiology at the University of Virginia, Charlottesville, agreed with this assessment. Although other studies underway will reexamine this issue, there was consensus from several speakers at the CRT symposium that the results of ATTRACT should not preclude intervention in patients at high risk of PTS.
“I believe there is a role for DVT intervention for symptomatic patients with an extensive [proximal iliofemoral] clot provided they have a low bleeding risk,” Dr. Soukas said.
Dr. Soukas reported no potential conflicts of interest.
WASHINGTON – On the basis of a large randomized trial called ATTRACT, many clinicians have concluded that pharmacomechanical intervention is ineffective for preventing postthrombotic syndrome (PTS) in patients with deep venous thrombosis (DVT). But weaknesses in the study design challenge this conclusion, according to several experts in a DVT symposium at the 2018 Cardiovascular Research Technologies (CRT) meeting.
“The diagnosis and evaluation of DVT must be performed with IVUS [intravascular ultrasound], not with venography,” said Peter A. Soukas, MD, director of vascular medicine at Miriam Hospital in Providence, R.I. “You cannot know whether you successfully treated the clot if you cannot see it.”
“There were lots of limitations to that study. Here are some,” said Dr. Soukas, who then listed on a list of several considerations, including the fact that venograms – rather than IVUS, which Dr. Soukas labeled the “current gold standard” – were taken to evaluate procedure success. Another was that only half of patients had a moderate to severe DVT based on a Villalta score.
“If you look at the subgroup with a Villalta score of 10 or greater, the benefit [of pharmacomechanical intervention] was statistically significant,” he said.
In addition, the study enrolled a substantial number of patients with femoral-popliteal DVTs even though iliofemoral DVTs pose the greatest risk of postthrombotic syndrome. Dr. Soukas suggested these would have been a more appropriate focus of a study exploring the benefits of an intervention.
The limitations of the ATTRACT trial, which was conceived more than 5 years ago, have arisen primarily from advances in the field rather than problems with the design, Dr. Soukas explained. IVUS was not the preferred method for deep vein thrombosis evaluation then as it is now, and there have been several advances in current models of pharmacomechanical devices, which involve catheter-directed delivery of fibrinolytic therapy into the thrombus along with mechanical destruction of the clot.
Although further steps beyond clot lysis, such as stenting, were encouraged in ATTRACT to maintain venous patency, Dr. Soukas questioned whether these were employed sufficiently. For example, the rate of stenting in the experimental arm was 28%, a rate that “is not what we currently do” for patients at high risk of PTS, Dr. Soukas said.
In ATTRACT, major bleeding events were significantly higher in the experimental group (1.7% vs. 0.3%; P = .049). The authors cited this finding when they concluded that the experimental intervention was ineffective. Dr. Soukas acknowledged that bleeding risk is an important factor to consider, but he also emphasized the serious risks for failing to treat patients at high risk for PTS.
“PTS is devastating for patients, both functionally and economically,” Dr. Soukas said. He called the morbidity of deep vein thrombosis “staggering,” with in-hospital mortality in some series exceeding 10% and a risk of late development of postthrombotic syndrome persisting for up to 5 years. For those with proximal iliofemoral DVT, the PTS rate can reach 90%, about 15% of which can develop claudication with ulcerations, according to Dr. Soukas.
A large trial that was published in a prominent journal, ATTRACT has the potential to dissuade clinicians from considering pharmacomechanical intervention in high-risk patients who could benefit, Dr. Soukas said. Others speaking during the same symposium about advances in this field, such as John Fritz Angle, MD, director of the division of vascular and interventional radiology at the University of Virginia, Charlottesville, agreed with this assessment. Although other studies underway will reexamine this issue, there was consensus from several speakers at the CRT symposium that the results of ATTRACT should not preclude intervention in patients at high risk of PTS.
“I believe there is a role for DVT intervention for symptomatic patients with an extensive [proximal iliofemoral] clot provided they have a low bleeding risk,” Dr. Soukas said.
Dr. Soukas reported no potential conflicts of interest.
WASHINGTON – On the basis of a large randomized trial called ATTRACT, many clinicians have concluded that pharmacomechanical intervention is ineffective for preventing postthrombotic syndrome (PTS) in patients with deep venous thrombosis (DVT). But weaknesses in the study design challenge this conclusion, according to several experts in a DVT symposium at the 2018 Cardiovascular Research Technologies (CRT) meeting.
“The diagnosis and evaluation of DVT must be performed with IVUS [intravascular ultrasound], not with venography,” said Peter A. Soukas, MD, director of vascular medicine at Miriam Hospital in Providence, R.I. “You cannot know whether you successfully treated the clot if you cannot see it.”
“There were lots of limitations to that study. Here are some,” said Dr. Soukas, who then listed on a list of several considerations, including the fact that venograms – rather than IVUS, which Dr. Soukas labeled the “current gold standard” – were taken to evaluate procedure success. Another was that only half of patients had a moderate to severe DVT based on a Villalta score.
“If you look at the subgroup with a Villalta score of 10 or greater, the benefit [of pharmacomechanical intervention] was statistically significant,” he said.
In addition, the study enrolled a substantial number of patients with femoral-popliteal DVTs even though iliofemoral DVTs pose the greatest risk of postthrombotic syndrome. Dr. Soukas suggested these would have been a more appropriate focus of a study exploring the benefits of an intervention.
The limitations of the ATTRACT trial, which was conceived more than 5 years ago, have arisen primarily from advances in the field rather than problems with the design, Dr. Soukas explained. IVUS was not the preferred method for deep vein thrombosis evaluation then as it is now, and there have been several advances in current models of pharmacomechanical devices, which involve catheter-directed delivery of fibrinolytic therapy into the thrombus along with mechanical destruction of the clot.
Although further steps beyond clot lysis, such as stenting, were encouraged in ATTRACT to maintain venous patency, Dr. Soukas questioned whether these were employed sufficiently. For example, the rate of stenting in the experimental arm was 28%, a rate that “is not what we currently do” for patients at high risk of PTS, Dr. Soukas said.
In ATTRACT, major bleeding events were significantly higher in the experimental group (1.7% vs. 0.3%; P = .049). The authors cited this finding when they concluded that the experimental intervention was ineffective. Dr. Soukas acknowledged that bleeding risk is an important factor to consider, but he also emphasized the serious risks for failing to treat patients at high risk for PTS.
“PTS is devastating for patients, both functionally and economically,” Dr. Soukas said. He called the morbidity of deep vein thrombosis “staggering,” with in-hospital mortality in some series exceeding 10% and a risk of late development of postthrombotic syndrome persisting for up to 5 years. For those with proximal iliofemoral DVT, the PTS rate can reach 90%, about 15% of which can develop claudication with ulcerations, according to Dr. Soukas.
A large trial that was published in a prominent journal, ATTRACT has the potential to dissuade clinicians from considering pharmacomechanical intervention in high-risk patients who could benefit, Dr. Soukas said. Others speaking during the same symposium about advances in this field, such as John Fritz Angle, MD, director of the division of vascular and interventional radiology at the University of Virginia, Charlottesville, agreed with this assessment. Although other studies underway will reexamine this issue, there was consensus from several speakers at the CRT symposium that the results of ATTRACT should not preclude intervention in patients at high risk of PTS.
“I believe there is a role for DVT intervention for symptomatic patients with an extensive [proximal iliofemoral] clot provided they have a low bleeding risk,” Dr. Soukas said.
Dr. Soukas reported no potential conflicts of interest.
EXPERT ANALYSIS FROM THE 2018 CRT MEETING