Early Hints of Low Adverse-Event Rate for 'Minimally Invasive' Partial-Support LVAD

September 12, 2012

September 11, 2012 (Seattle, Washington) — Short-term follow-up of only 20 patients with the latest version of the Synergy (CircuLite, Saddle Brook NJ) partial-support left ventricular-assist device (LVAD) suggests that it may present a lower risk of some adverse events that have beleaguered other LVADs, such as infections and thromboembolism [1]. If that big but still only potential advantage turns out to be real as the device is tested in a lot more patients and perhaps more directly compared with other LVADs, it could make the Synergy more appealing for patients who are still ambulatory and aren't necessarily close to the end stage of their heart failure.

And that is the population the device is actually designed for, observed Dr Daniel Burkhoff (Columbia University, New York, NY) when presenting the Synergy experience here at the Heart Failure Society of America 2012 Scientific Meeting. Burkhoff is CircuLite's medical director.

The much-debated idea is that LVADs might be an option earlier in the disease process than they are typically used, perhaps keeping the patient from sliding further clinically.

The Synergy pump was recently given the CE Mark of approval by European regulators, as reported by heartwire . It's still far from any FDA approval, however.

Assigned to comment on the latest Synergy experience after Burkhoff's presentation, Dr Robert L Kormos (University of Pittsburgh Medical Center, PA) agreed that "the trial suggests that a major reduction in adverse events compared with those seen with contemporary LVADs can be achieved through the strategy of early implantation in the spectrum of heart failure, with the minimally invasive approach that was used."

So, he said, "I seriously consider this a novel approach in the treatment of congestive heart failure," because it extends LVAD therapy to patients with fewer comorbidities and it has "potential to promote myocardial recovery and avoidance of the really horrible deleterious effects of congestive heart failure."

Synergy partial-support left ventricular-assist device [Source: CircuLite]

But the current experience is very limited; much more is needed, including the company's planned prospective trial of the device, before it's known whether the current low adverse event rate can be sustained, he observed.

The pump, which weighs about 25 g and is about the size of an AA battery, according to Burkhoff, is implanted subcutaneously with the flow lines connected to the circulation through a minithoracotomy. The pump and lines have a "quick-connect" design that makes device change-outs easier than with other LVADs, he said. It can maintain a flow of 1.5 to 4.25 L/min with effect of preserving pulsatile flow.

The 20 patients with the latest of the Synergy's four design incarnations, he reported, have had the device for a mean of 7.5 months and had "quite significantly impaired" baseline hemodynamics that were "indistinguishable" from those typical of patients receiving "full left ventricular-assist devices."

Over 12 weeks:

  • Mean cardiac output increased from 3.9 to 4.8 L/min (p<0.001).

  • Mean pulmonary capillary wedge pressure fell from 28 to 15 mm Hg (p<0.001).

  • There were also decreases in central venous pressure (p=0.006) and pulmonary arterial pressure (p<0.001).

  • Six-minute-walk distance increased by 135 m (p=0.006), and peak VO2 improved by 2.0-mL O2/kg/min (p=0.005).

"Aside from bleeding, which is really the one residual adverse event that we needed to deal with, a lot of the other events that are common in LVADs are really not present, at least in the short term in this small population of patients," Burkhoff said.

Bleeding requiring surgery occurred in 3.61% of patients within 30 days and in none after 30 days; the rate of any bleeding was 4.52% before day 30 and 0.46% after day 30. Rates of infections, renal dysfunction, neurologic dysfunction including ischemic or hemorrhagic stroke, peripheral embolic events, and right heart failure were negligible or zero.

Kormos questioned whether the reported data "separate the effects of patient selection [less sick patients than those typically getting LVADs] from the effects of the minimally invasive approach using this technology" in achieving the low adverse-event rate.

Burkhoff is an employee of CircuLite. Kormos reports he has nothing to disclose.

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