Ventilator Settings Linked to Success of Catheter Ablation for Afib

Outcomes improved with a novel ventilation protocol during radiofrequency ablation of paroxysmal atrial fibrillation (Afib), registry data across 12 institutions showed.

After hospitals implemented high-frequency, low-tidal-volume (HFLTV) ventilation during the procedure, freedom from all-atrial arrhythmia at 12 months increased compared with the previous standard ventilation protocol (85.6% vs 79.3%, P=0.041), according to Jorge Romero, MD, of Brigham and Women's Hospital and Harvard University in Boston, and colleagues.

The improvement was driven mainly by a reduction in recurrent Afib and was accompanied by a lower incidence of Afib-related symptoms (12.5% vs 18.9%, P=0.046) and hospitalizations (1.4% vs 4.7%, P=0.043), the multicenter REAL-AF registry showed.

"This is particularly important given that improvement in long-term outcomes did not require any specialized or additional equipment but instead relied on the existing equipment with slight and easy-to-implement modifications of the anesthetic technique," the authors emphasized in JACC: Clinical Electrophysiology.

A standard ventilation protocol during catheter ablation typically employs high tidal volumes with low respiratory rates. In contrast, HFLTV ventilation minimizes the downward shift of the diaphragm during inspiration, which might improve catheter stability and boost first-pass isolation during pulmonary vein isolation (PVI).

While the observational study couldn't draw causal conclusions, the researchers suggested that "the improved clinical outcomes may likely be attributed to the ventilation strategy," reasoning that no other ablation-related parameters were altered between standard and HFLTV ventilation groups, and all participants were off antiarrhythmic drugs after the blanking period.

"Moreover, these results are independent from operator experience, which is of utmost importance, particularly when performing procedures in low-volume and less-experienced centers," they added.

For years, researchers in the field of catheter ablation have tried and failed to increase freedom from all-atrial arrhythmia for Afib patients. Consistent success evaded operators even with the introduction of contact force (CF)-sensing technology and more extensive ablation lesion sets; cardiac pacing; high-power, short-duration ablation; and ablation indexes in 3D mapping systems, according to Romero and colleagues.

HFLTV would represent a novel, easily implemented strategy to improve catheter ablation's efficacy.

Indeed, the authors reported that the HFLTV group had shorter procedural times and total radiofrequency times, coupled with an improved 66.6% rate of first-pass PVI compared with 63.8% under standard ventilation (P=0.036). All patients tolerated the HFLTV ventilation protocol without an uptick in complications.

Going forward, "HFLTV ventilation could be a reasonable first-line ventilation strategy in patients undergoing Afib ablation," Romero and colleagues asserted.

Nevertheless, the good results in paroxysmal Afib may not necessarily apply to people with persistent Afib, who typically have worse results from catheter ablation with PVI, they cautioned.

For their report, the authors used the prospective REAL-AF registry that captures cases of catheter ablation of paroxysmal Afib with contact force technology, which currently includes only ThermoCool SmartTouch catheters. During the analysis period from January 2019 to August 2021, the cases were done by 18 operators at 12 institutions. Until the implementation of HFLTV in April 2020, standard ventilation was the norm.

Across the two groups receiving HFLTV (n=216) and standard ventilation (n=445), average age was 64.7 years. Women accounted for 46.1% of the patients. Patients with advanced chronic obstructive pulmonary disease, asthma, and pulmonary fibrosis were excluded.

Compared with controls, the HFLTV group had more baseline hypertension (63% vs 51.7%, P=0.008), a higher CHA₂DS₂-VASc score (2.7 vs 2.3, P=0.003), a lower left ventricular ejection fraction (56.1% vs 58%, P=0.018), and a smaller left atrial diameter (3.8 cm vs 3.9 cm, P=0.035).

The investigators acknowledged that their analyses did not account for these baseline characteristics.

Future research may compare HFLTV ventilation with high-frequency jet ventilation, which is also anticipated to increase catheter stability -- albeit with costly special equipment, they said.

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