First results of the POWER FAST III trial

The first results of the POWER FAST III trial showed that the number of oesophageal lesions was similar in patients who received high-power short duration (HPSD) radio-frequency (RF) pulmonary vein isolation (PVI) ablation and in patients who were treated with a conventional low-power long duration (LPLD) radio-frequency (RF) PVI ablation.

A recently published meta-analysis favoured HPSD PVI ablation over LPLD PVI ablation in terms of efficacy [1]. “However, this meta-analysis included mostly single-centre, non-randomised studies,” argued Prof. José Luis Merino (La Paz University Hospital, Spain) [2]. “Moreover, the rate of oesophageal injuries should be compared for the 2 treatment modalities.” The multicentre, randomised POWER FAST III trial (NCT04153747) included 267 patients with paroxysmal or persistent atrial fibrillation (AF), who were randomised 1:1 to receive HPSD-RF PVI (70 Watt for 9–10 seconds) or LPLD-RF PVI (25–40 Watt, guided by ablation lesion indexes). The primary safety outcome was the incidence of acute thermal oesophageal injuries at endoscopy. The primary efficacy endpoint was the incidence of atrial arrhythmias at 1-year follow-up.

After 1 year, the acute PVI efficacy was comparable for the 2 treatments with a 100% success rate for left PVIs and a 99.2% (HPSD arm) and 98.4% (LPLD arm) success rate for right PVIs. In addition, the first pass PVI rate was higher in the LPLD arm than in the HPSD arm (82% vs 66.7%; P=0.007). No significant differences were observed concerning acute spontaneous or adenosine PV reconnections. Also, the mean procedural duration was comparable for participants in the LPLD arm (191.5 minutes) and those in the HPSD arm (186.5 minutes; P=0.74).

The rate of acute oesophageal thermal lesions was similar for the treatment arms, with 6.5% in the LPLD and 7.5% in the HPSD arm (P=0.94). The complication rates were comparable (6.0% vs 7.9%; P=0.64). The rate of pericardial effusions was numerically 4 times higher in the HPSD arm (3.2%) than in the LPLD arm (0.7%) but this was not significant (P=0.2). Furthermore, the rate of systemic embolism trended towards significance in disfavour of the HPSD arm (3.2% vs 0%; P=0.055).

“The identical rates of oesophageal lesions are somewhat disappointing since the lesion sets that we place tend to be broader and more shallow for HPSD PVI ablation. It was expected that this procedure would spare the oesophagus,” argued Dr Boris Schmidt (Cardioangiologisches Centrum Bethanien, Germany). “In addition, the rates of pericardial effusions were high in the HPSD arm. The 9 seconds 70 Watt dose that was applied in this study might have been too much for some regions in the left atrium. To avoid oesophageal lesions in HPSD PVI ablation, temperature monitoring could be used as a safety measure.”

1. Ravi V, et al. Europace. 2021;23(5):710–721.
2. Castrejon S, et al. High radiofrequency power for faster and safer pulmonary vein ablation trial (POWER FAST III): preliminary safety and short-term results. Late-breaking science 2, EHRA 2022, 3–5 April, Copenhagen, Denmark.

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Posted on 1 June, 202213 June, 2022