Thrombus Aspiration Improves Clinical Outcomes in STEMI Patients

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The use of thrombus aspiration during primary percutaneous coronary intervention (PCI) improves in-hospital and long-term survival of patients with ST-segment elevation myocardial infarction (STEMI), according to results from a large, unselected cohort. The study, published online September 17, 2012, ahead of print in the European Heart Journal, also suggests that manual thrombectomy is particularly beneficial in patients with a total ischemic time of 180 minutes or less.

Researchers led by Javed Ahmed, MD, of Freeman Hospital (Newcastle-upon-Tyne, United Kingdom), conducted a retrospective analysis of 2,567 consecutive STEMI patients who underwent primary PCI between 2008 and 2011 at their center. Thrombus aspiration was at the discretion of the operator and was performed in 42.7% of patients (n = 1,095). All cases were done manually.

In-hospital complications (excluding death) were similar between the thrombectomy and nonthrombectomy groups (13.4% vs. 12.7%; P = 0.59). In-hospital mortality and long-term mortality at mean 9.9 months follow-up, the co-primary endpoints, favored the thrombectomy group. In addition, the rate of TIMI 3 flow grade after PCI was higher with vs. without thrombectomy (table 1).

Table 1. Primary and Secondary Endpoints

 

Thrombectomy
(n = 1,095)

Nonthrombectomy
(n = 1,472)

Adjusted OR
(95% CI)

P Value

In-hospital Mortality

2.7%

5.8%

0.51 (0.29-0.93)

0.027

Long-term Mortality

5.7%

11.6%

0.69 (0.48-0.96)

0.028

TIMI 3 Flow

94.6%

88.7%

1.92 (1.34-2.76)

0.0004


After adjustment for multiple factors including total ischemic time, stent use, pre-PCI TIMI flow grade, and GP IIb/IIIa use, longer term mortality was lower in patients with post-PCI TIMI 3 flow grade compared with those with TIMI 0, 1, or, 2 flow grade (6.9% vs. 26.4%; P < 0.0001).

In patients with left ventricular systolic function (LVSF) documented on discharge (n = 1,076), thrombus aspiration remained an independent predictor of reduced 1-year mortality even after correction for LVSF (adjusted HR 0.37; 95% CI: 0.19-0.72; P = 0.003).

At a cut-off point of 180 minutes, an interaction was noted between thrombectomy and total ischemic time (P for interaction = 0.024). Analyses were then performed separately for the 2 subgroups over or under the cut-off ischemic time. The association between thrombus aspiration and reduced longer term mortality was only significant in patients within the cut-off time (adjusted HR 0.41; P = 0.001) but not in patients with a total ischemic time greater than 180 minutes (adjusted HR 1.0; P = 0.99).

However, no interaction was seen between thrombectomy and the following factors:

  • Pre-PCI TIMI 2/3 flow grade (P for interaction = 0.16)
  • Age > 70 years (P = 0.72)
  • Female gender (P = 0.60)
  • Anterior MI (P = 0.55)
  • Diabetes (P = 0.22)

More Support for Routine Use of Thrombus Aspiration

According to Dr. Ahmed and colleagues, use of thrombus aspiration during PCI increased steadily across the study years in their cohort, likely as a result of the publication of the TAPAS trial (Svilaas T, N Engl J Med. 2008;358:557-567), which showed that thrombectomy results in better reperfusion and clinical outcomes than conventional PCI irrespective of baseline clinical and angiographic characteristics. Although TAPAS failed to demonstrate a benefit for thrombus aspiration on post-PCI TIMI flow grade or 30-day mortality, there was a reduction in all-cause and cardiac mortality at 1 year with thrombectomy. However, other meta-analyses of mortality outcomes with thrombus aspiration in primary PCI have demonstrated neutral outcomes. One explanation for the variance, the authors write, is that the “results might be due to differences in the type of thrombectomy device used as well as follow-up durations.”

They say the study “support[s] the use of thrombectomy during [primary] PCI and identif[ies] a subgroup in which thrombus aspiration is associated with better survival.” Further support is expected to come from the ongoing Thrombus Aspiration in ST-Elevation myocardial infarction in Scandinavia trial (TASTE), which aims to recruit 5,000 STEMI patients. Final data collection is expected in 2013.

‘Biologically Implausible’

In a telephone interview with TCTMD, Jeffrey W. Moses, MD, of Columbia University Medical Center/Weill Cornell Medical Center (New York, NY), expressed skepticism that thrombectomy could have such a profound effect on mortality and suggested instead that the differences between the 2 groups offer a more likely explanation.

“With all the confounders here, it certainly makes one believe that what we are seeing is an effect of patient selection,” he said. “Even though they did adjust for many factors, you still have a [carefully selected] population getting this therapy from different operators. It’s intriguing that there might be a time differential in terms of the ischemic time, where the benefit dissipates. That makes sense, but the profound mortality difference they show in this study is pretty staggering and it’s biologically implausible given all the negative trials of thrombectomy that have been published recently.”

But Dr. Moses agreed with the study authors that the most convincing data on mortality differences are still to come.

“It’s the single-center studies, including TAPAS, that showed a mortality difference with thrombectomy, so the jury is still out until [TASTE] is completed,” he said.

Study Details

Mean age of patients was 63.2 ± 13.4 years and 70% were male. The majority of thrombus aspiration (93%) was performed using the Export device (Medtronic, Santa Rosa, CA). In-hospital complications included:

  • Procedural cardiac complications (coronary dissection, perforation, side branch occlusion, no reflow, and tamponade)
  • Arterial access complications
  • Other (CVA, bleeding, re-intervention, and renal failure)

 


Source:
Noman A, Egred M, Bagnall A, et al. Impact of thrombus aspiration during primary percutaneous coronary intervention on mortality in ST-segment elevation myocardial infarction. Eur Heart J. 2012;Epub ahead of print.

 

 

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Disclosures
  • Drs. Ahmed and Moses report no relevant conflicts of interest.

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