By Dennis Thompson
THURSDAY, April 30, 2015 (HealthDay News) -- A mechanical device that restores a failing heart's ability to pump blood might contribute to a decline in memory and thinking in some patients, a new study reports.
Left ventricular assist devices are surgically implanted in patients with advanced heart failure who are awaiting a heart transplant or unable to receive one, said lead author Dr. Timothy Fendler, a research fellow at St. Luke's Mid America Heart Institute in Kansas City, Mo.
"These devices have become a mainstay of treatment for people with severe heart failure over the past 15 years, and offer really phenomenal survival benefits," Fendler said.
But Fendler is co-author of two studies that suggest survival due to a left ventricular assist device might come at a cost.
More than one in four patients who receive such a device experienced a notable decline in their ability to remember, plan and solve problems, one study found.
And about one-third of patients with the devices experienced death, diminished quality of life or poor health after receiving the implant, according to the other study.
Doctors can't prove the devices were the culprit, but they suspect the losses in brain function stem from major, minor and mini-strokes that occur due to blood clots caused by the devices, Fendler said.
"We know the risk of stroke is higher for these patients," he said. "The device itself, because it's a foreign body, it attracts blood clots and these can lead to strokes."
Blood thinning medications might help counter these effects, but "that's a tough balancing act, because you don't want to thin a person's blood so much that you increase their risk of bleeding events," Fendler said.
The implant, which is battery-operated, has a tube that draws blood from the left lower chamber of the heart, known as the left ventricle. The pump then sends the blood into the aorta, the main artery, according to the National Heart, Lung and Blood Institute.
Besides buying time for patients awaiting a heart transplant, the devices are used as a longer-term solution for end-stage heart failure patients when a transplant is not an option, the American Heart Association says.
In the first study, 1,173 patients from different hospitals underwent a thinking and memory test before their implant, and at each follow-up meeting with their doctor.
About 29 percent of patients suffered a significant decline in memory and problem solving within a year of receiving their implant, researchers found. They were more likely to have this decline if they were older and had been fitted with the device as a permanent therapy, rather than a temporary support while awaiting heart transplant.
The second study involved 164 device recipients at one hospital, whose health and quality of life were monitored between January 2012 and October 2013.
Researchers found that 58 patients had suffered a poor outcome within a year of receiving the implant. Thirty-seven of them died, 17 experienced a significant decrease in quality of life, three landed back in the hospital two or more times for heart failure, and one had a disabling stroke.
Patients with poor overall results had longer hospital stays for device placement, had been given the device as permanent therapy more often, and had more bleeding events, a common occurrence in patients with this device.
"The more we understand these different adverse events, the better we can help patients make informed decisions about these therapies that are wonderful but come with their own risks," Fendler said.
Such research is important because doctors are more frequently talking about using these devices to treat heart failure that is affecting a patient's lifestyle but not placing them at death's door, said Dr. Brahmajee Nallamothu, chair of Quality of Care and Outcomes Research for the American Heart Association.
"We need to understand these complications if we're going to start broadening their use," said Nallamothu.
But Nallamothu noted that Fendler's research only showed an association -- not a proven link -- between left ventricular assist devices and mental decline in some patients.
"These are really sick patients, and they have a lot of reasons to suffer cognitive decline," Nallamothu said. "These are people who otherwise without the device in all likelihood would die within a short time period. That's a real key point."
Findings from both studies were published April 29 in the journal Circulation: Cardiovascular Quality and Outcomes.
For more on left ventricular assist devices, visit the U.S. National Institutes of Health.