March 16th, 2015
A Requiem for Routine Thrombectomy?
Primary PCI is the treatment of choice in the early period of an acute MI. One limitation is the risk of dislodging part of the clot, leading to new downstream blockages of the microvasculature. One strategy that has been under development for a long time is thrombectomy, in which a device extracts the clot prior to the delivery of the stent. Following earlier success in small trials, the benefits of thrombectomy became controversial when a large trial, TASTE, found no evidence of benefit for the procedure.
TOTAL (Trial of Routine Aspiration Thrombectomy with PCI versus PCI Alone in Patients with STEMI), one of the largest trials ever to test a medical device, was presented at the American College of Cardiology meeting in San Diego and published simultaneously in the New England Journal of Medicine. The trial randomized 10,732 patients with acute ST- elevation MI undergoing primary PCI to routine upfront thrombectomy with the Medtronic Export catheter or no additional therapy. (The trial was investigator initiated but received funding from Medtronic.)
The primary outcome of the trial — a composite of CV death, recurrent MI, cardiogenic shock, or NYHA class IV heart failure within 180 days — occurred in 6.9% in the thrombectomy group versus 7% in the control group. There was still no difference when stent thrombosis and target vessel revascularization were added to the composite endpoint (9.9% versus 9.8%).
There was a small but statistically significant increase in the risk of stroke at 30 days in the thrombectomy group (0.7% versus 0.3%, HR 2.06, CI 1.13-3.75, p=0.02). This difference remained significant at six months. The investigators said that their stroke findings “cannot be easily explained.”
As in previous trials, the use of thrombectomy was associated with seemingly positive changes in surrogate outcomes, including improvement in ST-segment resolution and distal embolization. “This finding cautions against changing practice on the basis of trials showing an improvement in surrogate outcomes,” the authors wrote.
In an accompanying editorial, Filippo Crea writes that the stroke result “is difficult to interpret and is likely to be a chance finding…” The study was not powered to assess stroke. Further increasing doubt is the increased risk beyond the periprocedural period, he wrote.
But Crea says that the rigorous study design and large size lends credibility to the main findings of TOTAL. Although he suggests that it may be time “to prepare a requiem for routine manual thrombectomy” he said it is too early “to rule out the possibility that thrombus aspiration might be beneficial in high-risk patients.”