CardioBrief

The HeartMate II continuous flow LVAD outperformed its older cousin, the HeartMate XVE pulsatile flow LVAD, according to the results of the HeartMate II Destination Therapy Trial presented today at the AHA and published online in the New England Journal of Medicine.

The trial randomized 200 patients with advanced heart failure who were not eligible for transplantation. The primary endpoint, survival at two years free from disabling stroke or re-operation for device repair or replacement, was reached in 46% of patients who received the continuous flow (CF) device compared to only 11% who received the pulsatile flow (PF) device, a highly significant difference (p<0.001).

One and two year actuarial survival rates were:

• 68% and 58% for the CF LVAD
• 55% and 24% for the PF LVAD

The CF LVAD also bettered the PF LVAD across a wide spectrum of endpoints, including, notably, re-hospitalizations, which were reduced from 4.25 events per year to 2.64. In addition, CF LVAD patients were able to walk longer and had better quality of life than their PF LVAD counterparts. There was no significant difference in the rate of stroke between the two groups, though the trend favored the CF LVAD (0.13 versus 0.22 per patient-year).

“The newer pump is smaller, operates quietly and has demonstrated superior durability. Interestingly, it also pumps blood continuously, which reduces the systolic blood pressure. We believe that in the future there will be little need for pulsatile blood pumps,” said Joseph Rogers, a co-author of the study.

“The outcomes of this study are particularly impressive when you consider the status of these patients at the time they entered the trial,” said Mark Slaughter, in a Thoratec press release. “These patients have a similar profile to those in the REMATCH trial who were managed with the standard of care–optimal medical management–and had a two-year survival rate of eight percent versus the 58 percent achieved by the HeartMate II in this trial.”

Georg Wieselthaler, the trial’s discussant, noted that after the first six months the survival curve flattens, at least in the CF LVAD arm, and pointed out that “patients who get it earlier will have better outcomes.”

James Fang, in an accompanying editorial, wrote the following:

Philosophically, some view the use of a mechanical pump for heart failure as conceding the biologic battle; for others, it is a practical decision to refer a patient for left ventricular assist device therapy when contemporary therapies have been exhausted. Although the selection of patients, device durability and cost, and other considerations remain challenges in this rapidly evolving field, there is little doubt that left ventricular assist devices are viable and important options for patients with medically refractory advanced heart failure.

Click here for the Thoratec press release.

Here is the AHA press release:

Continuous flow heart pump improves survival more than pulsatile type
Study highlights:

• Continuous flow heart pump improved survival better than pulsating pump for heart failure patients ineligible for transplant.
• The new, continuous flow left ventricular assist device is smaller, quieter and more durable than pulsating models.

ORLANDO, Fla., Nov. 17, 2009 — A new, continuous flow heart pump, or left ventricular assist device (LVAD), delivered better two-year survival in advanced heart failure patients than the current pulsatile model, researchers reported in a late-breaking clinical trial presentation at the American Heart Association’s Scientific Sessions 2009.

In the HeartMate II Destination Therapy Trial, researchers tested a new device that helped heart failure patients who weren’t responding to optimal medical therapy and weren’t eligible for a heart transplant. They found significant improvement in outcomes of patients who received the continuous flow LVAD (HeartMate II) compared to those who received a pulsatile flow LVAD (HeartMate XVE), the only FDA-approved device for treating such patients.

“The results of this trial will alter the manner in which we provide mechanical circulatory support,” said Joseph G. Rogers, M.D., co-author of the study and medical director of the Duke Heart Failure Program at Duke University Medical Center in Durham, N.C. “In the past, mechanical pumps delivered blood in a pulsatile manner; in other words, they beat like a human heart.

“The newer pump is smaller, operates quietly and has demonstrated superior durability. Interestingly, it also pumps blood continuously, which reduces the systolic blood pressure. We believe that in the future there will be little need for pulsatile blood pumps.”

The study included 200 end-stage heart failure patients implanted at 38 U.S. medical centers between March 2005 and May 2007. All patients had failed optimal medical therapy and were ineligible for a heart transplant.

The primary endpoint was survival free from disabling stroke and device failure requiring re-operation at two years. Secondary endpoints included overall survival, adverse events, quality of life and functional capacity.

A greater proportion of continuous flow LVAD patients successfully reached the primary composite end-point compared to pulsatile flow (46 percent vs. 11 percent) — a highly significant finding, researchers said.

At one-year follow-up, 68 percent of the continuous flow LVAD patients had survived compared to 55 percent in the pulsatile flow group. At two years, survival was 58 percent for the continuous flow device vs. 24 percent with the pulsatile device.

Both groups experienced early and sustained improvements in their quality of life scores and functional capacity. The distance walked in six minutes (a common measure of functional abilities) increased from 182 to 318 meters in the continuous flow patients and from 172 to 306 meters in the pulsatile flow patients at one year, Rogers said.

Over the 24 months of the study, the rate of disabling stroke was similar in both study arms (11 percent for continuous flow LVAD vs. 12 percent for pulsatile flow LVAD).

In addition, 10 percent of the patients who received the continuous flow LVAD needed surgery to repair or replace the pump compared to 36 percent of patients with the pulsatile device.

Furthermore, other adverse events were less common in the continuous flow pump group than in the pulsatile one.

“Severe heart failure is associated with a very poor prognosis,” Rogers said. “Patients diagnosed with advanced heart failure treated with optimal medical therapy have a 10 percent to 20 percent survival rate in the ensuing two years. Further, these patients are unlikely to experience significant improvement in their quality of life or functional abilities with routine medical or electrical therapies.”

Transplantation is a standard treatment for patients with advanced heart failure. But an estimated 150,000 U.S. patients have advanced heart failure while the number of heart donors each year is about 2,100. “We believe that with improved technology and management strategies, LVADs will fill this important gap,” Rogers said.

Thoratec Corporation, in Pleasanton, Calif., funded the study.

Co-authors are: Mark S. Slaughter, M.D.; Carmelo A. Milano, M.D.; Stuart D. Russell, M.D.; John V. Conte, M.D.; David Feldman, M.D., Ph.D.; Benjamin Sun, M.D.; Antone J. Tatooles, M.D.; Reynolds M. Delgado, M.D.; James W. Long, M.D., Ph.D.; Steven C. Horton, M.D.; Thomas C .Wozniak, M.D.; Waqas Ghumann, M.D.; David J. Farrar, Ph.D.; and Howard Frazier, M.D.
Disclosures: Dr. Rogers has served as a consultant for Thoratec.

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