3D whole heart MR angiography image obtained in 67 seconds. Source: Toshiba Medical Systems

SAN FRANCISCO—Coronary thrombectomy as an adjunct to PCI was not associated with a significant reduction in infarct size compared with a control group but it was associated with a significantly higher rate of ST-segment elevation resolution, Anna Sonia Petronio, MD, of the cardiothoracic and vascular department at the University of Pisa, Italy, said Nov. 10 at the 2011 Transcatheter Cardiovascular Therapeutics' late-breaking clinical trial press conference.

The MUSTELA trial was designed to compare thombectomy with no thrombectomy in patients with STEMI and a high thrombus burden. Petronio and colleagues noted that it was unknown whether coronary thrombectomy improves myocardial perfusion and reduces infarct size and microvascular obstruction.

The prospective randomized included patients with STEMI with onset of less than 12 hours and a TIMI thrombus grade of greater or equal to 3 on diagnostic angiography. Patients with a previous MI on the ventricular wall, a PCI of less than two weeks or STEMI with cardiogenic shock were excluded. Primary end points were infarct size at three months assessed through MRI, and ST segment elevation resolution of greater than 70 percent at 60 minutes after primary PCI.

“The radial approach was encouraged, with direct stenting,” Petronio explained.

A total of 208 patients, divided equally into an aspirated group and a non-aspirated (control) group, participated in the trial. In the aspirated group, 54 patients underwent rheolytic trombectomy and 50 manual thrombectomy. The patients were followed for one year for major adverse cardiac events (MACE).

They found that 37.3 percent of the control group and 57.4 percent of the aspirated group had an ST-segment elevation resolution of greater than 70 percent. The reduction of infarct size was similar for both groups: a 19.3 reduction in the control group and 20.4 percent in the thrombectomy group.

“There was no difference in infarct size,” she said. “But there was a statistically significant microvascular obstruction more frequently in patients in the control group.”

There was no significant difference in MACE at one-year follow-up. The rheolytic thrombectomy approach proved more successful than the manual approach, the analysis showed.

The study affirmed that thrombectomy was feasible, with success rates of 100 percent and 98 percent in the rheolytic and manual subgroups, respectively. “There were no coronary complications with both devises, which is very important,” Petronio concluded. “Most important of all, there was no prolonged astole when the rheolytic system was used, especially for right coronary arteries, and there was never placement of a temporary pacemaker.”

She added that the investigators wanted to extend the study to a two-year follow-up.