ESC Congress FA eBook 2016 - 22

SELECTED UPDATES

Hot Topics in Arrhythmology
Written by Phil Vinall

Official Peer-Reviewed
Highlights From

October 2016

Miniature leadless pacemakers have the potential to minimize many of the complications associated with transvenous pacing systems. Philippe Ritter, MD, University Hospital of Bordeaux,
LIRYC Institute, Bordeaux, France, discussed the 2 systems that are currently available.
The Micra Transcatheter Pacing System (Medtronic Inc) is a small, single-chamber capsule
that uses VVIR (ventricular pacing with automatic rate adjustments) stimulation. It is delivered by
way of the femoral vein and is attached to the wall of the right ventricle. Micra is repositionable
and retrievable and may have an average battery life > 12 years. The Nanostim is longer but thinner than the Micra. Implantation is accomplished using a single-operator delivery catheter with
a deflectable tip to allow exact placement and repositioning. The average battery life is approximately 15 years.
In a prospective multicenter study, the Micra was successfully implanted in 99.2% of patients
[Reynolds D et al. N Engl J Med. 2016]. The rate of the primary efficacy endpoint (low and stable
pacing capture thresholds at 6 months) was 98.3% which was significantly better than a predefined
historical control group (P < .001). The median implantation time was 28 minutes. There were
no infections or dislodgement and 96% of patients experienced freedom from device/procedurerelated major complications at 6 months.
In a study using the Nanostim Leadless Pacemaker System (St Jude Medical) [Reddy VY et al. N
Engl J Med. 2015], successful implantation was reported in 95.8% of patients. The primary efficacy endpoint of both an acceptable pacing threshold and sensing amplitude through 6 months was
achieved by significantly more patients than seen with historical controls (90% of patients; P = .007).
Similar results were seen for the safety endpoint of freedom from device-related serious adverse
events through 6 months (93.3% of patients; P< .001) at 6 months.
Mattias Duytschaever, MD, St Jan Hospital Bruges, Belgium, reviewed new developments in
atrial fibrillation (AF) ablation that he believes are improving patient outcomes. When reviewing
paroxysmal AF, he focused on second-generation cryoballoon catheters and contact force sensing
RF catheters.
Second generation cryoballoons have a change in the refrigerating jets and in the distance from
the jets to the tip that results in a more homogenous circumferential lesion. After a single freeze,
isolation was accomplished in 94.1% of all identified pulmonary veins [Ciconte G et al. Heart
Rhythm. 2015]. At 12 months of follow-up, 82.3% of patients with paroxysmal AF were in stable
sinus rhythm. Compared to conventional irrigated RF technology, 2nd generation cryoballoon
was associated with a higher rate of persistent PVI when patient undergo a repeat procedure for
AF recurrence [Heeger CH et al. Circ Arrhythm Electrophysiol. 2015; Bordignon S et al. Europace.
2015].
Contact force (CF) sensing technology allows delivery of better and possibly more durable ablation lesions. Prof Duytschaever discussed 2 catheters: The TactiCath catheter (Endosense SA)
and the SmartTouch catheter (Biosense Webster Inc.). The TactiCath contains a force sensor that
allows continuous and real-time measurement and display of force applied by the tip. A fiberoptic sensor combined with an infra-red laser waveform that passes to the catheter tip experiences
microdistortion when force is exerted on the catheter tip, thus modifying the wavelength. Lateral
and axial forces are measured by the sensor that provides force vector. The tip of the SmartTouch
is mounted on a precision spring and allows deflection. CF is measured by magnetic sensors every
50 ms. The tip of the electrode is coupled to a transmitter coil and emits the location reference
signal, then the CF is averaged over one second. The system senses the sensor location, calculates
force based on the spring characteristics, and displays this on a 3D map [Moulton L. EP Lab Digest.
2011].
In patients with symptomatic paroxysmal AF treated with the CF technology and controls
treated with a non-CF device the CF catheter was found to be associated with significantly lower

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Table of Contents for the Digital Edition of ESC Congress FA eBook 2016