New LVAD May Benefit High-Risk PCI Patients


Major Finding: High-risk patients who were aided during PCI with an LVAD (Impella 2.5) had a 41% rate of major adverse events at 90 days, significantly better than the 51% rate in patients treated with a standard intra-aortic balloon pump. But in the intention-to-treat analysis, outcomes did not differ for the two groups at either 30 days or 90 days.

Data Source: PROTECT II, a randomized trial comparing LV support with the Impella 2.5 device and an intra-aortic balloon pump in 447 patients who were treated at 72 sites worldwide.

Disclosures: PROTECT II was funded by Abiomed, which markets the Impella device. Dr. O'Neill has been a consultant to Medtronic. Dr. Waksman has been a consultant to or received honoraria from Medtronic Vascular, Abbott Vascular, Biotronik, Merck, and Boston Scientific.

NEW ORLEANS – Introduced to the U.S. market in 2008 as an upgraded alternative to the intra-arterial balloon pump, the Impella 2.5 showed clear signs of better performance in high-risk patients undergoing percutaneous coronary intervention in a multicenter, randomized trial with 447 patients.

But once Impella 2.5 entered the U.S. market, enrollment into the study slowed dramatically. Eventually, researchers stopped the trial substantially short of its enrollment target, and the pivotal study's primary end point did not show a statistically significant benefit for Impella 2.5.

The trial also ran into a second problem with a major confounding issue: Interventional cardiologists used rotational atherectomy more aggressively in Impella-treated patients. They seemingly were emboldened by the added cardiac support, and Impella-treated patients had an unbalanced rate of adverse effects.

Despite these problems, the trial results showed a role for the Impella device in high-risk, low-cardiac-output patients undergoing PCI, Dr. William O'Neill said at the meeting

“This device produces superb hemodynamic support during high-risk interventions. It really allows a more complete procedure that leads to fewer late events,” explained Dr. O'Neill, an interventional cardiologist and executive dean for clinical affairs at the University of Miami.

“With these [high-risk] patients, we skate rapidly over thin ice. This device allows us the luxury of taking more time and doing a more complete and safer procedure. I think [that capability] will translate into increased use [of the device] in these high-risk patients,” he added.

Experts who heard the trial results were split on their interpretation of the findings.

“This was a negative study. What is driving the differences you see? I don't understand how to reconcile the results with your conclusion to go ahead [with using] this device,” commented Dr. Ron Waksman, director of experimental angioplasty at Washington (D.C.) Hospital Center.

But Dr. Roxanna Mehran gave the findings a much more positive spin (see box, below right).

PROTECT II was a prospective, multicenter, randomized, controlled trial of the Impella Recover LP 2.5 system vs. IABP (intra-aortic balloon pump) in patients undergoing nonemergent, high-risk PCI. The trial began in November 2007 at 67 U.S. sites, 4 sites in Canada, and 1 site in the Netherlands. It enrolled patients with either unprotected left main coronary disease and a left ventricular ejection fraction of 35% or less, or patients with triple-vessel coronary disease and an ejection fraction of 30% or less.

The primary end point was the 30-day rate of death, MI, stroke, need for repeat revascularization, need for cardiovascular surgery or vascular surgery for limb ischemia, acute renal dysfunction, increased aortic insufficiency, severe hypotension, need for cardiopulmonary resuscitation, ventricular tachycardia, or failure to reopen the target coronaries by PCI.

The patients averaged 67 years old, 80% were men, and 56% had New York Heart Association class III or IV heart failure. Their average Society of Thoracic Surgeons (STS) mortality score was 6, their average SYNTAX (Synergy Between PCI With Taxus and Cardiac Surgery) score was 30, and 63% were considered ineligible for surgery. “The population was “extraordinarily high risk, the most complex patients ever enrolled in a multicenter, randomized, controlled trial,” Dr. O'Neill said.

There were 447 patients enrolled in PROTECT II before the study's data and safety monitoring board stopped the trial last December citing “futility” on the primary end point. This number was 70% of the number of patients originally identified as needed to produce a statistically significant result for the primary end point. Enrollment into the study sharply slowed once the Impella device came onto the U.S. market in June 2008.

During PCI, the participating operators generally managed the Impella patients more aggressively. Heparin was given to 94% in the Impella arm and to 82% in the IABP control arm. Rotational atherectomy was performed in 15% of the Impella patients and in 10% of patients in the IABP arm, a statistically significant difference. Also, participating operators used atherectomy more aggressively in the Impella patients, with an average of five atherectomy passes per patient, compared with two passes in the IABP patients.


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