Late-Breaking Trials Include First Human Tests of Miniature, Leadless Pacemaker
During Friday’s Late-Breaking Clinical Trials session, researchers reported on the first human trial of a new miniaturized transcatheter pacing system, the use of baroreflex activation therapy for the treatment of heart failure with reduced EF, and the effect of linear ablation in substrate-based AF. Other researchers provided updates from the PRO-MRI and HeartLight studies.
Philippe Ritter, MD, of Hôpital Haut-Lévêque in Pessac, France, presented results of the the MicraTM Transcatheter Pacing Study, the first in-human tests of a novel, self-contained, miniaturized, leadless pacemaker. The study involved patients having Class I or II indications for VVI pacing who underwent implantation of a transcatheter pacing system (TPS) from the femoral vein, and fixated in the right ventricle using four protractible nitinol tines.
Dr. Ritter reported on the trial’s first 96 patients with follow-up of at least one month. The findings include results from implanting physicians at 23 centers in Europe, the United States, Malaysia, and Japan.
“All implant attempts [100%] were successful and were performed in a wide variety of patient profiles,” Dr. Ritter said. “At implant, one month, and three months, we saw only very small complication rates, comparable to those of conventional pacemakers. We think this is a revolutionary device, but long-term safety and benefits need to be further evaluated.”
Baroreflex Activation Therapy
Increased sympathetic and decreased parasympathetic activity contribute to heart failure symptoms and disease progression. Baroreflex activation therapy (BAT) results in a centrally mediated reduction of sympathetic, and an increase in parasympathetic activity.
Michael R. Zile, MD, of the Medical University of South Carolina, presented the results of a study designed to compare the safety and efficacy of BAT in heart failure patients who were and were not receiving chronic resynchronization therapy (CRT). Because patients treated with CRT may have less sympathetic/parasympathetic imbalance, Dr. Zile and his colleagues hypothesized that patients without CRT would have a greater response to BAT.
To test that hypothesis, the researchers randomized 146 NYHA Class III patients with ejection fraction ≤35% on guideline-directed medical therapy (GDMT) to ongoing GDMT, or ongoing GDMT plus BAT. At six months in the no-CRT group, Dr. Zile reported that Quality of Life scores significantly improved, six-minute hall walk distance and LVEF significantly increased, and heart failure hospitalizations were significantly reduced in BAT patients compared to controls.
“This is an exciting new therapy with great potential,” Dr. Zile said. “This represents a therapy that can be applied to those patients for whom you have exhausted all other therapies.”
ICDs and MRIs
The presence of an implantable cardiac defibrillator (ICD) is usually considered a contraindication for magnetic resonance imaging (MRI) for fear of lead heating, generator malfunction, and patient injury. Khaled Awad, MD, of the University of Alabama at Birmingham, presented results of a study looking at the efficacy of the Biotronik Iforia ProMRI ICD System, which is specifically designed to be MRI conditional.
For this study, researchers at 40 U.S. centers enrolled 170 patients after implantation of an Iforia ICD, consisting of either a dual-chamber DR-T system or a single-chamber VDD VR-T DX system. Patients were eligible for enrollment five weeks after ICD implant. Non-diagnostic cardiac or thoracic spine MRI was performed at least one week after enrollment.
“We observed no adverse outcomes and, most importantly, we saw no impact from the MRI on the device’s main function,” Dr. Awad said.
Dr. Awad and his colleagues believe their results demonstrate the clinical safety and efficacy of the Iforia ProMRI ICD System and believe this device platform will allow patients with ICDs to safely undergo MRI in 1.5T scanners for various clinical indications.
HeartLight Study Update
Vivek Y. Reddy, MD, of Mount Sinai School of Medicine in New York, presented results from the HeartLight Study, which was designed to evaluate the efficacy and safety of pulmonary vein isolation (PVI) procedures performed using visually guided laser balloon (VGLB), as compared to standard-of-care radiofrequency ablation for paroxysmal atrial fibrillation (PAF).
“VGLB is unique in that the operator delivers ablative energy under direct visual guidance,” Dr. Reddy said. “In other words, it’s a balloon with a camera.”
Based on their findings, Dr. Reddy and his colleagues believe that visually guided PVI will prove to be as safe and effective as the standard RF ablation catheter once operators become more experienced with the new technology.
Linear Ablation
More advanced forms of AF are associated with lower success rates after PVI, and more extensive lesion sets are generally advocated, although recent data have questioned this approach. Gareth J. Wynn, MBChB, of the Liverpool Heart and Chest Hospital, reported the results of a multicenter trial from the United Kingdom evaluating the impact of additional bi-atrial linear ablation compared with a strategy of wide antral pulmonary vein isolation alone, facilitated by peri-procedural pharmacological substrate modification.
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