Pulmonary vein isolation (PVI) is the cornerstone of catheter ablation procedures in patients with paroxysmal atrial fibrillation (PAF) [1]. However, the incidence of atrial fibrillation (AF) recurrence remains high [2], mostly due to pulmonary vein (PV) reconnection [1], emphasizing the formation of transmural lesions to achieve complete conduction block along the ablation lines [3].

Previous studies have shown that elimination of the negative component of the unipolar electrogram (UP-EGM) during radiofrequency applications reflects transmural lesions. The persistence of such a negative component consistently corresponds to non-trans mural lesions [4].

Pulmonary vein isolation (PVI) is the cornerstone of catheter ablation procedures in patients with paroxysmal atrial fibrillation (PAF) [1]. However, the incidence of atrial fibrillation (AF) recurrence remains high [2], mostly due to pulmonary vein (PV) reconnection [1], emphasizing the formation of transmural lesions to achieve complete conduction block along the ablation lines [3].

Previous studies have shown that elimination of the negative component of the unipolar electrogram (UP-EGM) during radiofrequency applications reflects transmural lesions. The persistence of such a negative component consistently corresponds to non-trans mural lesions [4].

The high-power short duration (HPSD) RF application applies to all RF energies delivered at more than 40 W [5]. Higher the power more is the resistive heating causing wider tissue injury [5]. The lesion size with HPSD is larger in width but lesser in depth compared to lower powers with longer duration [5]. In contrast, RF applications of lower power and longer duration result in larger dissipation of RF energies deep into the tissues due to conductive heating causing tissue destruction at greater depths [6]. Hence, there is a risk of collateral tissue damage [5].

HPSD ablation has been advocated as a means to minimize the risk of collateral organ damage as the lesions are smaller in depth. However, Maintaining a high power for a constant duration in the absence of a guide may not be the right strategy [5].

Unipolar waveform modification by complete elimination of the negative component may serve as a guide for HPSD ablation [5].

Inclusion Criteria:

• Paroxysmal atrial fibrillation

Exclusion Criteria:

• Age< 18 or > 80 years old,
• Atrium (LA) diameter > 50 mm,
• The presence of a mechanical mitral valve prosthesis,
• Left ventricular ejection fraction < 40%,
• Abnormal thyroid function,
• Contraindication to anticoagulant therapy,
• Current malignancy,
• Prior catheter or surgical AF ablation.