Reducing thrombus burden prior to PCI with the X-Sizer catheter system leads to better reperfusion, greater ST-segment resolution and lower rates of distal embolization. ¡°Successful PCI was defined in the past as normal TIMI-3 flow, but now we know that TIMI-3 flow is only the tip of the iceberg¡±, said Thierry Lefevre, MD, of Institut Hospitalier Jacques Cartier in Massy, France.

X-AMINE ST was a European multi-center trial comparing PCI with stenting to PCI with stenting after the use of the X-Sizer catheter system (ev3). The X-sizer system is designed to remove thrombus that may be obscuring the view of the culprit lesion. X-Sizer combines vacuum technology with a patented helix cutter in the tip of a small catheter. When used, the system creates a vacuum effect designed to capture and remove occlusive material. The Archimedes screw is designed to grab thrombus on contact, quickly drawing it in, shearing and removing it. For the current study, researchers enrolled 201 patients who had acute MI within 12 hours, ST-segment elevation, and a TIMI flow of between zero to one. ¡°Patients were at high risk of distal embolization¡±, Dr. Lefevre said. Mean age of patients was 61. Time from onset of MI to the first coronary angiogram was about 255 minutes with no significant difference between the two groups. GP IIb/IIIa inhibitors were used in 58% of the control group and 54% of the treatment group. Direct stenting was more frequently used in the X-Sizer group.

The success rate with the X-Sizer device was 89%. Thrombus removal was obtained in 95% of cases; 39% was complete removal and 61% partial. Procedure time was 10 minutes longer in the X-Sizer group. Researchers assessed a primary outcome of the sum of ST-segment resolutions and found a significant benefit in favor of the X-sizer group at 8.5mm compared to 6.8mm in the control group. ST-segment resolution of more than 50% was obtained in 67% in the X-Sizer group compared to 53% in controls, a comparison that was statistically significant. Final TIMI-3 flow was higher in the X-Sizer group at 96% compared to 89% in controls. The difference was not statistically significant.

A composite outcome of adverse clinical cardiovascular events was experienced by 16% of the control group compared to 4% of the treatment group, a highly statistically significant difference. Distal embolization occurred in 10% of control patients compared to 2% of treated patients. A composite of angiographic outcomes was recorded in 20% of the control group compared to 6% in the X-Sizer group. Angiographic success was achieved in 87% of treated patients compared to 79% of controls; this was not statistically significant. Dr. Lefevre said there was no significant difference in one-month outcomes, but ¡°the most important goal is to obtain ST-segment resolution as soon as possible¡±.