High Power Short Duration Radiofrequency Ablation of Atrial Fibrillation using the QDOT MICRO* Catheter

Recurrence of atrial fibrillation (AF) after pulmonary vein isolation (PVI) is
common and electrical reconnection between the pulmonary veins and the left
atrium is a frequent finding in patients undergoing redo ablation procedures.
Efforts to improve outcome of catheter ablation for AF are directed towards
creation of complete and durable lesion circles. Conventional radiofrequency
(RF) ablation is typically performed with power set at 30-40 Watt for a
duration of 20-30 seconds. Previous preclinical studies suggest that ablation
with higher power and shorter duration (HPSD) may result in more continuous and
more durable ablation lesions with a similar safety profile as compared to
conventional ablation lesions. This new technique may consequently improve
outcomes of RF ablation for AF. Moreover, HPSD ablation of AF may significantly
reduce RF duration, which could potentially lead to shorter anaesthesia,
fluoroscopy and procedure duration.
Recent developments in catheter design resulted in the QDOT MICRO* catheter
(Biosense Webster), a novel CE-marked contact force-sensing catheter optimized
for temperature-controlled RF ablation with microelectrodes and 6 thermocouples
for real-time temperature monitoring. This catheter enables very high power
short duration (VHPSD, 90W-4s) ablation when used in combination with a RF
ablation algorithm that modulates power to maintain target temperature during
VHPSD lesion formation.
Recent improvements in cardiac magnetic resonance (CMR) imaging and image
analysis enable studying atrial wall tissue characteristics. By applying this
imaging strategy after ablation, transient (edema) and persistent (fibrosis)
effects of RF ablation in the left atrial wall and surrounding tissues may be
visualized and quantified.
However, the short-term and long-term effects of VHPSD ablation on ablation
lesion formation as assessed by CMR are currently unknown. We hypothesize that
VHPSD ablation results in limited edema formation due to improved catheter
stability, while concurrently providing predictable lesion formation without
collateral tissue damage.

The main goals of this study are to study the effects of VHPSD ablation on the
duration of a pulmonary vein isolation procedure, and on transient (edema) and
persistent (fibrosis) effects of VHPSD ablation in the left atrial wall.

Prospective single-center intervention study.

Patients will undergo PVI ablation with the QDOT MICRO* catheter using
VHPSD-settings (90 watt, 4 seconds). CMR imaging will be performed at 24-48
hours and 3 months follow-up

Compared to conventional ablation, VHPSD ablation using the QDOT MICRO*
catheter has been shown to result in similar ablation lesion volumes, but with
a larger diameter and a smaller depth. This favourable profile yielded
predictable ablation lesion dimensions both in animal experiments and in recent
clinical studies, which may increase safety and improve procedural efficacy.
Experience with this new technique, however, remains limited.
All patients will receive standard preprocedural and follow-up medical care for
PVI including CMR imaging at baseline and Holter monitoring at follow-up. In
addition, CMR imaging will be performed immediately after PVI (24-48 hours
after PVI procedure) and at 3 months follow-up to assess post-ablation effects.
The additional risks associated with repeated CMR imaging are minimal.
Gadolinium is a safe contrast agent, which is frequently used in clinical
practice. Intravenous gadolinium administration may cause minimal injection
site reactions (e.g. pain, cold or burning sensation). As with other
contrast-agents, anaphylactic-like reactions may occur, although this is very
unusual. Patients with a known (suspected) allergic reaction to gadolinium or
severe kidney failure (GFR <30 ml/min/kg) will be excluded.
This study is designed to study the effects of VHPSD-ablation in AF patients.
Future AF patients and patients with other arrhythmias who are eligible for
ablation may benefit from insights gained by this study.