The world's smallest, minimally invasive cardiac pacemaker - the Micra Transcatheter Pacing System (TPS) - was successfully implanted in nearly all of the patients participating in an international clinical trial. The trial, which involved 725 patients at 56 centers, showed  the Micra TPS (about the size of a large vitamin) was successfully implanted in nearly all patients – 99.2 percent (719 of 725).

It also registered wide margins in its safety and effectiveness endpoints. In fact, approximately 96 percent of patients experienced no major complications, which is 51 percent fewer than those in patients with conventional pacemakers. Major complications include cardiac injuries (1.6 percent), groin site complications (0.7 percent), and pacing issues (0.3 percent).

The results were contained in a study presented this week at the 2015 American Heart Association Scientific Sessions, and simultaneously published in The New England Journal of Medicine.


Emory Healthcare cardiologists were among the first in Georgia and the United States to begin implanting the Micra TPS last year. Emory was the top enrolling U.S. site in the clinical trials. Dr. Michael S. Lloyd, associate professor at the Emory University School of Medicine, noted his excitement with the trials: "We were pleased to participate in this important trial, as this will likely be the way pacemakers are implanted in the future. The outstanding results are very encouraging and will allow us to continue to offer this novel device as a safe alternative to our patients."

Lloyd, who is a cardiac electrophysiologist, implanted the first Micra TPS in April 2014 at Emory University Hospital. He says there are some three million people in the world living with pacemakers and around 600,000 pacemakers are implanted every year.

The procedure involves the tiny device that is about one-tenth the size of a conventional pacemaker, that is delivered through a catheter inserted in the femoral vein to the inside of the heart. Once in place, it securely attaches to the endocardial tissue of the heart wall and sends electrical pulses to the heart through electrode tips whenever it senses abnormal heart rhythms.

Unlike traditional pacemakers, the Micra TPS does away with the use of wires threaded through blood vessels to connect to the heart. These wires, known as "leads," are sometimes the source of serious medical complications, such as infection and vein injury. Another major difference is that implanting the Micra TPS does not require a surgical incision and the creation of a "pocket" under the skin. Conventional pacemakers require a more invasive procedure.

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