Aspiration Thrombectomy on the Decline as New Study Affirms No Benefit in STEMI

The use of manual aspiration thrombectomy in primary PCI for STEMI has declined significantly since 2011, according to a new analysis of National Cardiovascular Data Registry (NCDR) CathPCI numbers.

The decline, reported this week by investigators led by Eric Secemsky, MD (Beth Israel Deaconess Medical Center, Boston, MA), followed publication of the large, randomized TASTE and TOTAL trials, which showed the procedure to not only be ineffective for improving clinical outcomes but also associated with an increased risk of stroke following PCI.

“The initial approval and use of the device was really driven by anecdotal evidence and surrogate endpoints in some smaller randomized trials,” Secemsky told TCTMD, adding that it was “pretty impressive” how quickly interventionalists took up the practice. “I think there’s a reflex as an interventionalist where you see a thrombus [and] it makes sense that if you retrieve it your outcomes are going to be better. That prompted operators to use the device. Then we had these two large randomized, controlled trials that really debunked the idea that using it routinely would improve meaningful clinical outcomes.”

Following the publication of TASTE and TOTAL, the routine use of aspiration thrombectomy was downgraded to a class III recommendation in a 2015 focused update to PCI and STEMI guidelines from the American College of Cardiology, the American Heart Association, and the Society for Cardiovascular Angiography and Interventions. Whether interventionalists accepted the trial results and adopted the updated professional guidelines was unclear, however, prompting the analysis from Secemsky et al.

There are also lingering questions, particularly related to whether patients with a large thrombus burden might benefit more from aspiration, since thrombectomy was mandated in the treatment arm of the randomized, controlled trials regardless of thrombus burden.

“There was always a thought that if there was a selective use of aspiration thrombectomy, where you’re really only using it when there’s a need, we might find a treatment benefit,” Secemsky explained to TCTMD.

In part to address this theory, the current analysis was designed to compare the safety and effectiveness of selective thrombectomy in a broad, unselected population using an instrumental variable analysis (IVA).

The analysis was published online January 9, 2019, ahead of print in JAMA Cardiology. 

Substantial Variation in Practice

During the study period, investigators saw wide variation in operator use of manual aspiration thrombectomy, ranging from no use to 83.3% of all primary PCIs. Slightly more than one-third of operators did not use aspiration thrombectomy between 2009 and 2016 and nearly one-quarter only used the device in 5.4% of cases or less. Nearly 16% of operators used aspiration thrombectomy in 21.6% to 83.3% of all primary PCIs for STEMI.

Over time, aspiration thrombectomy usage in STEMI patients declined, falling from a peak of 13.8% in 2011 to less than 5% by mid-2016.

The wide variation in use is likely the result of physician preference, said Secemsky. Given this, the researchers were able to “exploit” the variation in a way to naturally select patients for treatment.

“That’s the point of the instrumental variable analysis,” said Secemsky. “The independence of the operators’ obligation to use the device selects patients not because of the presence of thrombus but just on the basis of preference. . . . It’s a great way to overcome some of the treatment selection bias that inherently flaws a lot of the comparative effectiveness analyses.”

In the IVA, there was no difference in the risk of in-hospital mortality but there was a small increased risk of in-hospital stroke among patients treated with aspiration thrombectomy. At 30 and 180 days, there was no difference in the risk of death or stroke, nor were there differences in risks of heart failure and hospital readmission, between those treated with or without aspiration thrombectomy.

“Even in a selectively applied manner, aspiration thrombectomy doesn’t appear to be reducing any hard clinical outcomes,” said Secemsky. “Again, I say that with qualifications because there are definitely some situations where the catheters can be useful. This type of analysis might not really capture the ‘super’ selective cases we encounter in the cath lab. I’m an interventionalist, and I’ve cut down my use significantly, but I still use it on occasion when I feel it might help get through a case.”

Aid in Procedure, Not to Reduce Future Events

To TCTMD, Dharam Kumbhani, MD (UT Southwestern Medical Center, Dallas, TX), who was not involved in the study, said that from the “big picture standpoint” the new data are reassuring given the clinical trial results.

“In all these analyses, what’s always interesting is to see the variation in care between operators,” he said. “If every operator was down to 4% or 5%, I think that would make sense, but there are clearly some operators who are still using it. It speaks to the gaps in care.”

Sanjit Jolly, MD (McMaster University, Hamilton, Canada), the lead investigator of TOTAL, said he was also comforted by the change in clinical practice but was slightly surprised by the data, mainly because he thought use of aspiration thrombectomy would have been much higher “in its heyday.” And while there is some speculation thrombectomy might benefit patients with high thrombus burden, a subgroup analysis from TOTAL showed that thrombectomy didn’t improve outcomes in patients with the highest burden of thrombus.

“I think there’s probably still a lot of people who believed in thrombus aspiration because it certainly is very satisfying to remove thrombus and make the vessel look better. Sanjit Jolly

He pointed out, however, that thrombus burden was assessed by the investigator prior to wire crossing, and not after it, and as such, the group couldn’t fully rule out a potential benefit in select patients.

“I think there’s probably still a lot of people who believed in thrombus aspiration because it certainly is very satisfying to remove thrombus and make the vessel look better,” said Jolly. “In patients with the highest thrombus burden even after you open the artery with a small balloon, do those patients benefit? I think there still are unanswered questions there.”

Nonetheless, aspiration thrombectomy does carry risks, as evidenced by the increased risk of stroke post-PCI in TOTAL and the NCDR data, he said.

In practice, Jolly will perform “selective bailout” thrombus aspiration after opening the artery with a small-diameter balloon in approximately one out of every 20 patients. “There are just some cases where you can’t achieve TIMI 3 flow just because there’s so much thrombus,” he said. “Reflexively we want to achieve TIMI 3 flow because it’s associated with outcomes instead of leaving the artery closed and calling it a failed procedure.”

Like the others, Kumbhani uses thrombectomy as more of a tool to aid in the procedure rather than a means to improve clinical outcomes.

“There are other nontangible aspects that are helpful from an interventional perspective,” he said, noting that thrombectomy might improve flow or aid in visualization, which can help in accurately sizing the stent. “[I] might use it in patients with high thrombus burden because it lets me do my job better.”

Responsive to Evidence   

For Secemsky, the study showed that interventional cardiologists reacted appropriately to the TASTE and TOTAL results.

“The academic and interventional community have been willing to perform these studies, and the operators responded to them,” said Secemsky. “We really do, as interventionalists, latch onto and follow the high-quality data that comes out and our practice changes because of it.”

He noted that clinical guidelines tend to lag behind the trials and this is reflected in this new analysis. For example, although the 2015 focused update downgraded aspiration thrombectomy, the recommendation was published after its use had already started to decline following the publication of TASTE and TOTAL. This might have implications for assessing health care quality, said Secemsky.

“If we’re going to use guidelines as an assessment of how well operators are performing high-quality procedures and evidence-based medicine, then we should probably be doing a better job of updating the guidelines to reflect evolving data,” he said.