Pulmonary Vein Isolation Strategy of Very High Power Short Duration in Patients With Paroxysmal Atrial Fibrillation

Pulmonary Vein Isolation Strategy of Very High Power Short Duration in Patients With Paroxysmal Atrial Fibrillation: Q-INDEX Trial

This study aims to investigate the effect of reducing ablation time for a hybrid approach of vHPSD and AI-guided ablation using the QDOT Micro catheter in PVI among patients with PAF.

Radiofrequency catheter ablation has become a cornerstone strategy for the rhythm control of AF. During the last decade, catheter technology has revolutionized and, accordingly, clinical outcomes after the ablation and procedural efficacy have been improved.

In recent years, the use of the CLOSE protocol employing contiguous, closely spaced applications and targeted ablation index (AI) values has translated into robust acute and long-term success rates for PVI, typically with the power delivery of up to 35 W, and more recently with 40 to 50 W, in power and temperature-controlled mode.

Contiguous ablation using very high-power, short-duration ablation at 90 W over 4 seconds is expected to shorten procedure time. However, changes in lesion geometry and the altered impact of catheter stability on lesion quality may influence procedural efficiency, safety, and effectiveness.

The Q-FFICIENCY trial showed that the vHPSD (90 W, 4 sec), temperature-controlled radiofrequency ablation (25/50 W) has comparable efficacy to conventional-power temperature-controlled ablation.

However, the efficacy of vHPSD ablation may depend on PV thickness due to its lesion characteristics. Therefore, AI-guided ablation may have merits over vHPSD ablation in thickened PV segments. According to the POWER PLUS trial, the proportion of 1st-pass PVI with vHPSD ablation was numerically lower than that of the conventional ablation, although there was marginal significance; 83.9% vs. 90.0%, p-value =0.085.

According to the OPTIMUM trial, a study conducted by our group, roof and anterior walls of the left atrium often require higher AI targets due to their thickness.

Therefore, a hybrid approach that combines both vHPSD and AI-guided ablations according to PV segments may achieve both high efficacy and short ablation time for PVI. The investigators of the POWER PLUS trial also speculated that the hybrid approach based on tissue thickness might offer the optimal balance of procedural efficacy.

However, up to date, no studies have investigated the efficacy and safety of the hybrid approach for PVI. More data is needed to suggest that the hybrid approach could be useful for PVI.

Therefore, this study aims to investigate the effect of reducing ablation time for a hybrid approach of vHPSD and AI-guided ablation using the QDOT Micro catheter in PVI among patients with PAF.

Inclusion Criteria:

• Patients undergoing PVI for PAF

Exclusion Criteria:

• Aged less than 19 years
• Patients with persistent AF
• Patients with previous ablation or surgery for AF
• Patients with intracardiac thrombus or thromboembolic events within the previous 90 days
• Patients with cardiac surgery or acute coronary syndrome within the previous 90 days
• Patients with contraindication(s) for using oral anticoagulants
• Patients with LA anteroposterior diameter of more than 55 mm
• Patients with left ventricular ejection fraction less than 35%
• Pregnants or those who plan to become pregnant during the study
• Life expectancy less than a year