A group of researchers were able to discover that a leadless cardiac pacemaker that has been transplanted in the heart's ventricle (right lower chamber of the heart) was able to successfully help patients persistently for six months. The clinical trial revolved around the effects of the Nanostim^TM leadless pacemaker by international medical device firm, St. Jude Medical Inc.

Cardiac pacemakers send electrical impulses to the heart so that it can beat in normal rhythms. These devices are usually prescribed in patients with disorders that make them exhibit irregular heartbeats. Pacemakers are known to cause complications such as infections and other problems due to the pacemaker leads, which are the electrodes used to contact the heart. The Nanostim^TM is a leadless cardiac pacemaker applicable for patients with pacemaker needs for a single ventricle. This is not transplanted surgically and only utilizes a catheter.

The researchers performed the study by implanting the leadless pacemakers to patients who require a single-chamber ventricular pacemaker device. They then established the main criteria for efficacy, which is the period of pacing threshold and the sensing amplitude for six months. The primary criteria for safety include the absence of any device-related adverse effects for six months. Initially, the researchers performed the pre-determined end points on the first 300 participants, who were able to finish six months of follow-up. The efficacy and safety scores were then compared with actual performance objectives and yielded 85 percent and 86 percent respectively.

In June 2015, a total of 526 patients were assessed. The findings of the study, published [pdf] in the New England Journal of Medicine, showed that 95.8 percent or 504 of 526 patients were implanted with the pacemaker successfully.

The efficacy rate for the primary cohort (first 300 patients) was accomplished in 270 of the patients and the safety rate was fulfilled in 280 of the participants. After six months, 6.7 percent of the patients developed adverse effects, which include dislodgement, cardiac damage and rise in pacing threshold, which required the replacement of the device.

The team of researchers is excited to share the findings of the study about the LEADLESS II, which persists to provide proof that Nanostim is indeed safe and effective, said Dr. Vivek Reddy, the study's lead author and director of electrophysiology at The Mount Sinai Hospital. Through the LEADLESS II, scientists are able to further their knowledge regarding pacing systems and have more options, especially for clinicians who are looking for less invasive interventions that may be suitable for patients who require permanent single-chamber pacing treatment.

Photo: Steve Jurvetson | Flickr