New cardiac medical devices offer options

Dr. Miguel Leal, Dr. Michael Field

Pictured above, L to R: Dr. Miguel Leal, Dr. Michael Field. Not pictured: Dr. Rodrick Deaño, Dr. Steve Ewer, Dr. Kurt Jacobson, and coordinator Mary Francois.

From the first pacemaker implanted in 1958 to today’s cutting-edge tools, technological innovations in cardiovascular medical devices have opened possibilities for patients living with heart conditions. Recently, clinicians with the UW Health Clinical Cardiac Electrophysiology and Interventional Cardiology programs entered a new era: they’ve begun to place two different devices recently approved by the Food and Drug Administration. The first is a miniaturized, leadless pacemaker (the Micra® Transcatheter Pacing System, pictured at upper right). The second is a Left Atrial Appendage Closure implant (the WATCHMAN™ LAAC Implant, pictured at lower right).

“The Micra TPS allows us to provide a patient with cardiac pacing in the ventricle without having to implant an endovascular lead (or wire), or to have a pulse generator implanted in the chest. This minimizes the risk of infection and eliminates the risk of lead failure,” said Miguel Leal, MD, assistant professor (CHS), Cardiovascular Medicine and director of the UW Health Device Clinic & Lead Management Program.

Leadless pacemaker technology is still at an emerging stage, and Dr. Leal explained that devices such as these are expected to be used preferentially for patients with conditions that increase peri- and post-operative risk of a traditional transvenous pacemaker implant. This would include patients with a prior history of endovascular or intracardiac infections, venous occlusions, or significant stenosis (narrowing) of the veins that would ordinarily be used to house pacemaker wires. Other possibilities include young patients for whom indwelling endovascular hardware for many decades would be an undesirable burden, or patients with limited venous access due to other conditions such as cancer and kidney disease. “As the device gains more track record, it is conceivable that it may constitute a new standard of care in the years to come, but that is not the focus at the present time,” said Dr. Leal.

The tiny, leadless pacemaker is a breakthrough, though—the first of its type to be approved by the FDA. (Editor’s note: Richard Page, MD, George R. and Elaine Love Professor and chair, Department of Medicine, chairs the FDA committee that approved both of these medical devices.) At present, the Micra TPS is only available for single-chamber ventricular-based pacing, as its atrial component is still under development. “In selected patients, this may constitute the safest and most viable form of delivering cardiac pacing in situations where the use of a traditional device may be too risky or simply not feasible,” said Dr. Leal.

The Watchman LAAC implant is intended for patients living with non-valvular atrial fibrillation (AF), which is the most common form of AF in developed nations. AF carries a 3- to 5-fold increased risk of ischemic stroke, and anticoagulation therapy is generally used to mitigate this risk. However, some patients living with AF have a contraindication for anticoagulation, such as bleeding or risk of falls. “The most compelling indication for this device is in patients with high risk of stroke due to atrial fibrillation who have contraindications to long-term anticoagulation but who are suitable for short term anticoagulation around the time of device implant,” said Michael Field, MD, associate professor (CHS), Cardiovascular Medicine.

The device closes off the left atrial appendage (LAA) to prevent any blood clots that form in the LAA from entering the blood stream and potentially causing a stroke. In two clinical studies, PROTECT AF and PREVAIL, the device was shown to be non-inferior to warfarin for prevention of stroke in patients with AF who were eligible for warfarin. Further studies are both needed and underway, explained Dr. Field, who advises that patients who can be safely managed with warfarin or novel oral anticoagulation agents should probably continue those medications.

“What we need data on is the efficacy of Watchman versus aspirin or clopidogrel for stroke prevention in people who cannot take warfarin or novel oral anticoagulants (NOACs). This is a question that we hope will be answered by the ASAP-TOO trial, which just started enrolling. Also, if PROTECT and PREVAIL could be repeated against a NOAC, it would be more timely and relevant to practice, especially since an important finding in PROTECT and PREVAIL was a reduction in hemorrhagic stroke versus warfarin which is similar to what we see in the trials comparing the NOACs to warfarin,” said Dr. Field.