Millions of people around the world are living with irregular heartbeats. The most common type, atrial fibrillation, puts individuals at a greater risk of suffering a stroke.
A new high-tech device aimed to lessen the risk of stroke in patients with atrial fibrillation, called Watchman, is undergoing clinical trials at 30 hospitals in the United States, including Aurora St. Luke’s Medical Center in Milwaukee.
The Watchman device was developed by Atritech Inc., a medical device company based in Plymouth, Maine. Dr. Jasbir Sra, and Dr. Tanvir Bajwa are the first Wisconsin physicians to implant the new device in patients.
“Atrial fibrillation is the most common heart rhythm problem,” said Bajwa. “It isn’t a lethal rhythm problem, but because of the irregular heart beat, people with this type of arrythmia are more at risk for stroke, which can be a major disability for people, particularly those who are older.”
In a patient with atrial fibrillation, the chambers of the heart do not contract in a synchronized fashion because of an electrical abnormality, Bajwa said.
“They just fibrillate or quiver rather than beating,” he said. “The quivering allows blood to ‘pool’ and clot inside the chambers, particularly in the left atrial appendage.”
Most strokes for patients with atrial fibrillation are caused when the clot escapes the appendage and reaches the brain, Bajwa said.
The Watchman, a device that looks like a small expandable parachute, is implanted via catheter into the left atrial appendage of the heart and closes off the appendage which prevents blood clots from forming and entering the blood stream.
It is a minimally invasive procedure done under the guidance of an electrocardiogram, Bajwa said.
The Watchman is self-expanding and blocks the entrance to the appendage so no clot can form there. Patients typically remain in the hospital overnight, which is a significantly shorter stay than those who have open heart surgery, Bajwa said.
Prior to the Watchman, physicians could surgically close up the left atrial appendage during open heart surgery or they could treat the patient with pharmaceutical blood thinners like Warfarin or Coumadin to try to prevent clots from happening, Bajwa said.
“We know that closing off the left atrial appendage is both possible and successful when it comes to reducing the risk of stroke,” he said. “We can’t perform that procedure on everybody coming in with atrial fibrillation though, and it’s usually only done on patients already coming in for invasive surgery, like a bypass. So we resort to using blood thinners to try to prevent clots from forming, but thinners also carry their own risks for patients, particularly when aging.”
The risk of stroke increases for patients with atrial fibrillation as they age, and is more common among people with high blood pressure, diabetes and coronary heart disease, Bajwa said.
“The risks of using blood thinners to treat potential clotting in aging-patients is also high since elderly people tend to suffer more falls and are at a greater risk for heavy bleeding if on these types of drugs,” he said.
Atritech Inc. did an original study and published data that clearly indicated that by closing the left atrial appendage with the Watchman device, physicans were able to reduce strokes in their patients with atrial fibrillation.
“There is no question about it,” Bajwa said. “The food and drug administration requested another study be done under the auspices that physicians in other areas could also effectively complete the procedure without serious complications.”
Atritech Inc. and the Watchman device technology were acquired by Massachusetts-based Boston Scientific earlier this year. The company has successfully completed additional medical device testing internationally and is in progress with a clinical trial in the United States. Aurora St. Luke’s Medical Center was the only clinical site chosen in Wisconsin for the project.
“What we are looking for is proof that the concept has been undoubtedly proven,” Bajwa said. “The data will assure the FDA that the procedure can be done safely without any problems temporary or long term.”
According to Bajwa, about 5 percent of patients in Atritech’s previous clinical trial suffered a severe side-effect known as cardiac tamponade, a condition in which fluid accumulates in the pericardium or the sac in which the heart is enclosed.
“The atrial wall is very thin and so in some cases putting the device in caused additional complications,” Bajwa said. “That’s why the FDA was concerned and ordered an additional trial conducted. Multiple centers, multiple hands need to perfect the procedure and refine the technique.”
Bajwa and his colleague, Sra, expect to treat 30 to 40 patients at St. Luke’s before the end of the clinical trial in late 2012 or early 2013.
“The technique has already been proven successful,” Bajwa said. “In five years or so, I believe this will be an effective useful tool for a percentage of the patients living with atrial fibrillation. If we can give one third or one fourth of the people at risk for stroke due to atrial fibrillation an alternative to anticoagulants, I see that as a huge success for the medical industry.”
