The first randomized trial comparing three ablation strategies for the treatment of persistent atrial fibrillation (AF) and long-standing persistent AF — the OASIS trial — found pulmonary vein antrum isolation (PVAI) plus posterior wall ablation and non-pulmonary vein trigger ablation to be significantly more effective than the use of focal impulse and rotor modulation (FIRM)-guided ablation (rotor ablation) alone or rotor ablation with PVAI.
The OASIS trial was one of six presented at Friday’s Late-Breaking Clinical Trials session.
In the OASIS trial, 113 non-paroxysmal AF patients were randomized to a FIRM-only group (group 1), a FIRM plus PVAI group (group 2), or a PVAI plus posterior wall ablation and non-pulmonary vein trigger ablation group (group 3), said Andrea Natale, MD, FHRS, the study presenter.
The primary endpoint was freedom from AF/ atrial tachycardia (AT) when the patients were off anti-arrhythmic drug (AAD) therapy after a blanking period. Secondary endpoints included acute procedural success, which was defined as termination of AF or 10 percent or greater slowing into AT.
At 12-month follow up, only 4 percent of patients in group 1 were free of AF/AT off AADs, 52.4 percent of patients in group 2 were AF/AT free off AADs, and 76 percent of patients in group 3 were AF/AT free off AADs. Enrollment in group 1 was terminated early for futility.
Among patients with persistent AF, the success rate was 53 percent in group 2 and 72 percent in group 3. Among patients with long-standing persistent AF, the success rate was 50 percent in group 2 and 84.6 percent in group 3, said Dr. Natale, Executive Medical Director of the Texas Cardiac Arrhythmia Institute at St. David’s Medical Center and Professor of Medicine at Dell Medical School, both in Austin, Texas.
“In my lab, the results of this study spell the end of our use of rotor ablation,” Dr. Natale said.
EFFORTLESS Study
A study of patients with a subcutaneous ICD implant in the EFFORTLESS registry concluded that subcutaneous ICD provides reliable treatment of ventricular tachyarrhythmias, with an appropriate shock rate comparable to that of conventional ICDs, said Lucas V. A. Boersma, MD, PhD, a cardiologist at St. Antonius Hospital in Nieuwegein, the Netherlands.
In addition, the study presentation conclusion noted that the appropriate shock conversion rate was comparable with an appropriate shock efficacy comparable to that of conventional ICDs.
The EFFORTLESS registry contains data on 985 patients at 42 medical centers in 10 European countries implanted with a subcutaneous ICD between 2009 and 2014. The pre-defined endpoints of the study were 30- and 360-day complications as well as the occurrence of shocks for AF/SVT. Appropriate and inappropriate shock episodes were reported by site and classified by a sensor-event committee.
At one-year or more follow up, the study found that device extraction occurred for infections in 2.4 percent of patients, the need for ATP therapy in 0.5 percent, failed conversion at implant in 0.4 percent, and the need for bradycardia pacing in 0.1 percent. There were no reports of lead failure or endocarditis. The complication-free rate was 95.9 percent at 30 days and 91.7 percent at 360 days, Dr. Boersma said.
Leadless Pacemakers
A study presented by Vivek Y. Reddy, MD, Director of the Electrophysiology Laboratories at Mount Sinai Medical Center in New York, compared the rates of acute and mid-term adverse events associated with leadless cardiac pacemakers with the adverse event rates associated with transvenous pacemakers based on data from the LEADLESS II clinical trial and Truven MarketScan databases.
Using data on the Nanostim (St. Jude Medical Inc.) leadless pacemaker, Dr. Vivek and his colleagues compared adverse event rates for 718 leadless pacemaker patients with data on 10, 521 transverse pacemaker patients. They found that acute complications occurred in 5.8 percent of the leadless pacemaker patients, mostly in the first month post-transplant, compared with acute complications in 12.7 percent of patients given single-chamber right-ventricular pacemakers.
Acute complications in the leadless pacemaker group included device dislodgement and pericardial effusion, while complications in the transverse pacemaker patients included lead-related adverse events, thoracic trauma, and infections. Mid-term complications occurred rarely in the leadless pacemaker patients, but in 5.4 percent of the single-chamber right-ventricular pacemaker patients.
Dr. Reddy and colleagues concluded that leadless pacemakers have clear treatment advantages in relation to the lead-related and infection complications associated with transverse pacemakers.
LAA Excision
A study of the effect of left-atrial appendage (LAA) excision on outcomes in patients with persistent atrial fibrillation treated with surgical ablation found that LAA excision added to pulmonary vein isolation (PVI) did not reduce the rate of recurrent AF, said Alexander Romanoff, MD, PhD, FHRS, from the State Research Institute of Circulation Pathology in Novosibirsk, Russia.
Dr. Romanoff and colleagues randomly assigned 176 patients with persistent AF to video-assisted surgical ablation with PVI alone or PVI plus LAA excision and followed up with the patients at 18 months postprocedure. The primary endpoint was freedom from any documented AF recurrence lasting longer than 30 seconds after a single ablation procedure.
At 18 months, 87 percent of patients assigned to ablation with PVI alone were free of recurrent AF, compared with 90 percent of patients assigned to ablation with PVI plus LAA excision, Dr. Romanoff said.
In addition to the primary outcome, there were no significant differences in the secondary endpoints, including freedom from AF after ablation and freedom from any atrial arrhythmias, he said.
SmartTouch Catheter
Waqas Ullah, PhD, a Cardiology Researcher at St. Bartholomew’s Hospital in London, United Kingdom, presented a randomized trial of the treatment of patients with paroxysmal AF undergoing paroxysmal AF ablation using a SmartTouch catheter with or without knowledge of contact force (CF) data.
The study showed that availability of CF data did not affect complication rates, but was associated with contact force extremes, suggesting knowledge of CF data may improve the safety and efficacy of paroxysmal AF ablation. Access to CF data was associated with a reduction in pulmonary vein reconnections, but not an improvement in one-year success rates, Dr. Ullah said.
The trial enrolled 120 paroxysmal AF patients at seven UK centers. Patients undergoing ablation for paroxysmal AF for the first time were randomized to ablation performed with or without access to CF data. The patients showed a 32 percent reduction in acute PV reconnection rates from ablation performed with access to CF data, and a 22 percent reduction in acute reconnection rates from ablation performed without access to CF data.
Pulmonary Vein Re-isolation
The results of a randomized, controlled trial comparing routine pulmonary vein re-isolation (the repeat electrophysiology study group) as a treatment for drug-refractory paroxysmal AF following an initial PVI procedure vs. standard care after PVI found that re-isolation of late pulmonary vein reconnections is more effective than the current standard care by preventing AT recurrences.
Eighty patients with drug-refractory paroxysmal AF were randomized to either standard care after initial PVI or a repeat EP study two months after PVI regardless of symptoms, said Dhiraj Gupta, MBBS, Consultant Cardiologist at the Liverpool Heart and Chest Hospital in the United Kingdom.
The initial PVI consisted of contact force-guided radiofrequency ablation using 3-D mapping and automated lesion tagging. AADs were stopped at four weeks. The patients’ pulmonary veins were checked with 3-D mapping and a 20-pole circular catheter at the time of the repeat EP study. Researchers re-ablated all sites that showed late reconnection.
Absolute freedom from AT and improved quality of life were significantly higher in the repeat study group compared with standard care.
