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Tortuosity of the infarct-related artery and the presence of calcified or bifurcated lesions increase the risk of thrombus aspiration failure during primary percutaneous coronary intervention (PCI), according to research published in the June 2011 issue of JACC: Cardiovascular Interventions. But, the results show, there is no mortality penalty for aspiration failure.

Investigators led by Robbert J. de Winter, MD, PhD, of the Academic Medical Center (Amsterdam, The Netherlands), analyzed data from 1,399 STEMI patients who underwent attempted thrombus aspiration during primary PCI at their center.

Aspiration failure was defined as the inability to reach and/or cross the occlusion with the aspiration catheter for effective thrombus removal. The researchers looked at which baseline and angiographic parameters increased the chances of aspiration failure or the inability to remove any aspirate and how these influenced outcomes out to 1 year.

The aspiration catheter failed to cross the lesion in 10.3% of patients. On multivariate analysis, only the presence of marked proximal tortuosity and calcified or bifurcated lesions in the infarct-related vessel were independently associated with failed aspiration (table 1).

Table 1. Predictors of Failure of Thrombus Aspiration

In 27.3% of cases in which the aspiration catheter successfully crossed the lesion, no aspirate could be retrieved. Independent predictors of lack of aspirate were age over 60 years and the circumflex artery as the infarct-related artery.

Notably, aspiration failure did not increase mortality risk. One-year mortality was 6.2% in patients with failed thrombus aspiration compared with 6.4% among those who had successful aspiration (HR 0.98; 95% CI 0.49-1.95; P = 0.95). The mortality rate for patients in whom the lesion was successfully crossed but no aspirate was retrieved was 6.7% compared with 6.3% among patients with aspirated material (HR 1.08; 95% CI 0.64-1.80; P = 0.78).

Easy Does It

“Most predictors [of failure] are lesion rather than patient specific and pretty much expected: tortuous vessels, calcified vessels etc., where getting the device to the lesion is problematic,” said David Cox, MD, of Lehigh Valley Hospital (Allentown, PA), in an e-mail communication with TCTMD. “The key point emphasized in both TAPAS [Percutaneous coronary intervention in Acute Myocardial Infarction Study] and this study is that PCI operators should not force the device and cause harm. That was the major problem with the AiMI [AngioJet Rheolytic Thrombectomy In Patients Undergoing Primary Angioplasty for Acute Myocardial Infarction] trial, in which many of the increased deaths in the AngioJet group could be attributed to forceful manipulation of the thrombectomy device.”

“We must listen to the aspiration catheter,” Dr. Cox advised. “If it is not crossing the lesion, it is not meant to. Don't force it.”

In an accompanying editorial, Bimmer E. Claessen, MD, of the Cardiovascular Research Foundation (New York, NY), and George D. Dangas, MD, PhD, of Mount Sinai Medical Center (New York, NY), write, “[A]fter the identification of predictors of [thrombus aspiration] failure, the question remains whether the failure rate can be limited. Although 3 different [thrombus aspiration] catheters were used in this study, its retrospective nature and differences in device design precluded a comparison of failure rates among the devices. Hypothetically, improved [thrombus aspiration] devices engineered for optimized delivery may increase success rates. Likewise, improved aspiration capacity of manual thrombus aspiration devices may lead to an increased yield of thrombotic debris. Moreover, success rates will intuitively increase with operator experience.”

Why Not Give It a Try?

“The outcomes of this study are not adjusted for imbalances in target vessel, shock, etc, so we cannot use them as an efficacy guide,” observed Jeffrey W. Moses, MD, of Weill Cornell Medical College (New York, NY), in an e-mail communication with TCTMD. “Only randomized data will clarify that. As of now, I’d say why not try thrombus aspiration? The limited randomized controlled trial data available show favorable results for mechanical treatment with aspiration catheters.”

“INFUSE-AMI (Anterior Myocardial Infarction) will offer some answers in a randomized controlled-trial fashion with multiple international centers,” said Dr. Cox. “And I think that trial will help us sort this out even more by measuring infarct size with magnetic resonance imaging. It is impossible to do a study large enough to be powered for mortality, but if we don’t see any significant difference with infarct size using aspiration thrombectomy in INFUSE AMI, we'll get a clearer answer [about whether or not it is effective].”

Study Details

Thrombus aspiration was performed with 3 devices: 7-Fr Rescue catheter (Boston Scientific/Scimed, Maple Grove, MN), 6-Fr Export aspiration catheter (Medtronic Vascular, Santa Rosa, CA), or 6-/7-Fr Proxis embolic protection device (St. Jude Medical, St. Paul, MN).

Note: Drs. Claessen and Dangas are faculty members of the Cardiovascular Research Foundation, which owns and operates TCTMD.

2. Claessen BE, Dangas GD. Thrombus aspiration in primary percutaneous coronary intervention: How to manage failure. J Am Coll Cardiol Intv. 2011;4:643-644.

• Dr. Cox reports serving on the steering committee for INFUSE AMI.
• Dr. Dangas reports receiving research support from Bristol-Myers Squibb/Sanofi-Aventis and The Medicines Company and consulting fees from Abbott Vascular, AstraZeneca, Cardiva, Cordis, and Regado Biosciences.

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