BOSTON—Patients with heart failure who failed standard, optimal cardiac resynchronization therapy (CRT) approaches had significant improvements in clinical outcomes after receiving a novel device that provided endocardial left ventricular stimulation.

However, lead researcher Vivek Y. Reddy, MD, of Mount Sinai School of Medicine in New York, said the WiCS-LV (EBR Systems) pacing system was associated with some safety issues. Reddy presented results of the small, nonrandomized study on May 14 during a late-breaking clinical trials session at Heart Rhythm 2015.

The WiCS-LV, which provides leadless pacing with a subcutaneous generator, is not FDA-approved.

Of the 35 patients who were implanted with the device, four had safety events within 24 hours. Two patients had vascular complications, including one who required surgery. Another patient died before the implantation, but the researchers did not attribute the death to the device. The fourth patient had an issue with the pacing pellet used in the procedure.

“We believe all of these safety events are things that are fixable,” Reddy said. “But ultimately, I think what the study showed is that left ventricular pacing is possible. It appears to confer significant benefits. We really need to understand, if we do this in a large number of patients, how safe this can be.”

Reddy said CRT is safe and effective in most patients with heart failure and a wide QRS. However, 20 percent to 40 percent are nonresponders to the therapy and others have technical issues due to implantation failures. Previous data showed that pacing directly from within the left ventricle could help nonresponders.

The SELECT-LV (Safety and Performance of Electrodes Implanted in the Left Ventricle) study examined an ultrasound-based technology for endocardial left ventricular pacing in which a subcutaneous battery emits ultrasonic pulses to the left ventricle. The trial included 39 patients enrolled in six European centers. If patients were not taking oral anticoagulants, the anticoagulation regimen consisted of dual antiplatelet therapy.

At baseline, the mean age was 65, the mean ejection fraction was 26 percent, while 88 percent of patients were males. All patients met the current guidelines for CRT, but they were considered conventional CRT failures.

“These are patients who clearly would benefit from CRT,” Reddy said.

Of the 39 patients, four did not undergo implantation. All but one of the 35 attempted implants were successful.

After implantation, patients had follow-up visits at one week, one month, two months and six months and had their devices checked every three months. They are scheduled to have annual assessment each year for five years.

Between 24 hours and one month after the implantation, eight patients had safety events. In addition, three patients had device-related events and premature battery depletion between the one-month and six-month follow-up period. Reddy said the issue was due to a transmitter and has since been resolved.

At one month, the mean QRS was reduced by 50 milliseconds. The mean ejection fraction increased from 27 percent at baseline to 33.7 percent at six months. During that same time period, the mean New York Heart Association classification improved. There were also reductions in end diastolic and systolic volumes.

“Despite the safety complications that clearly appeared in this population, overall when you look at the composite global score of clinical efficacy, including mortality and heart failure hospitalization and functional class and symptom assessment, you see that the SELECT-LV patients improve,” Reddy said.