Catheter for AF Maps, Ablates, and sees inside the heart

LISBON – A single balloon catheter contains many features to treat atrial fibrillation (AF). One trial showed that the multi-electrode and radio frequency (RF) balloon catheter with integrated mapping, pacing capability, and video camera achieved high levels of pulmonary vein (PV) isolation with short ablation times and device-related complications.

The Luminize catheter (Boston Scientific) consists of six forward electrodes and 12 equatorial ablation electrodes around the catheter head.

The integrated mapping and stimulation capabilities made it possible to evaluate in real time the isolation of photovoltaic cells and phrenic nerve capture. The integrated cameras validated the contact of the electrodes by direct visualization and allowed to adapt the radiofrequency dosage according to the contact in order to optimize the ablation.

Presentation on behalf of investigators of the safety and performance testing of the Apama RF balloon catheter system for the isolation of pulmonary veins in the treatment of paroxysmal atrial fibrillation (AF-FICIENT I), Amin Al-Ahmad, MD, Texas, Cardiac Arrhythmia, Austin, explained that the catheter can perform ablation in different ways.

It can opt for either a unipolar device, that is to say using the poles of the different electrode, either for a bipolar device, in which the current flows between two adjacent poles, or finally, multipolar if all poles are selected. The apical and equatorial electrodes can be combined to best adapt to the injured anatomy.

For the test, patients received a dose of RF from 6 to 10 watts using the catheter, with confirmation of the pulmonary vein isolation for the purpose of testing. a circular mapping catheter or Luminize balloon electrodes. At the discretion of the operator, oesophageal monitoring or diversion and general anesthesia were used.

This prospective multicenter, nonrandomized, pilot study was conducted in two phases (phase 1, n = 18, phase 2, n = 81).

Patients enrolled were aged 18 to 75 years (average in both phases, 58 years old, 68% male, left ventricular ejection fraction, 60%), had symptomatic paroxysmal AF (phase 1, 78%; phase 2, 100%) and had not been successfully treated with clbad I or III antiarrhythmic drugs.

In phase 2, treatment was almost universally effective in terms of isolated veins and successfully treated patients.

Between Phase 1 and Phase 2, improvements were made to the catheter, which allowed it to have greater flexibility in its direction and to add more electrodes to allow signal detection.

"The duration of the procedure has improved significantly after the improvements to the devices, from an average of 173 minutes to an average of 73 minutes," said Al-Ahmad. "This reflects both the improvements made to the device and its experience."

In phase 2, there were fewer ablations per patient and shorter procedure, fluoroscopy and balloon residence time. There were approximately two applications per vein, with six to 10 ablation lesions per patient in phase 2.

No serious adverse events related to the device were observed at 30 days and no evidence of VP stenosis in patients for whom cardiac imaging was available (0/32).

Al-Ahmad noted that the results of the study were limited by the lack of data on the long-term absence of atrial fibrillation with this device.

Philipp Sommer, MD, Electrophysiology Clinic of the Ruhr University in Bochum, Bad Oeynhausen, Germany, commented on the study. He said that many new devices are coming on the market and that "all these devices have one thing in common": they want to combine the best design features and functions of different current models.

While single ended RF catheters are good for high resolution mapping and ablation anywhere, they are not good for fast PV isolation or ease of use. , did he declare. And the balloons can quickly isolate the veins and are easy to use, but they are currently limited for high resolution mapping and ablation at any location. Combining the best aspects of the current separate technologies in the Luminize catheter "is something really nice," as the results of this study show, he said.

Sommer pointed out that one of the strengths of the study lies in the cohort's demographic data and in the data on the duration and effectiveness of the procedure in phase 2. The non-irrigated nature of the procedure was a factor limiting, which raises the possibility of silent embolisms. Oesophageal temperature monitoring was not mandatory, with the possibility of thermal injury. There was no voltage mapping to demonstrate what he called the "isolation level".

He also commented that post-procedure imaging only involved 32 out of 99 patients and that without it, it would be unclear whether PV stenosis would develop. And finally, he said that the device could be "expensive" because of the cameras that are part of it.

In response, Al-Ahmad commented theheart.org | Medscape Cardiology that Sommer "raised many very important and interesting points", but that cost did not belong to it. "Believe it or not, cell phone camera technology has changed the world, and implementing this type of technology in a catheter is no longer prohibitive," he said. "In fact, I am told that this catheter can be comparable to any other balloon catheter in terms of cost."

It is appropriate that the other points raised by Sommer are valid and will be taken into account in the next study, including monitoring of the esophagus and brain MRI. He explained that MRI would look for asymptomatic lesions in the brain reported with all catheters and all technologies, "the importance of which is not entirely clear … [For] any new catheter, the FDA will ask for this data. "

He predicts that major studies should begin by the end of this year. The device is under development and is not yet available for sale or use.

Al-Ahmad maintains consulting, royalty, property or shareholder relationships with Boston Scientific. Sommer is a member of the Advisory Board and has received conference fees and research funds from Abbott.

2019 European Heart Rhythm Association (EHRA) Conference: Presentation 182. Presented on March 17, 2019.