Background

Cryoballoon (CB) pulmonary vein isolation (PVI) has become a routine treatment option for patients suffering from symptomatic atrial fibrillation (AF). Pulmonary vein (PV) occlusion is a key factor of lesion formation. Fluoroscopy and contrast medium injection are usually implemented to assess PV occlusion prior to ablation. A novel pressure waveform analysis tool, which is incorporated into the CB system console, enables contrast medium-free assessment of PV occlusion during CB-PVI. 

Aims

To analyze safety and effectivity of pressure waveform-based PV occlusion assessment during CB-PVI.

Methods

Consecutive patients with symptomatic paroxysmal or persistent AF undergoing CB-PVI were prospectively enrolled. A patient cohort undergoing conventional CB-PVI with venograms for occlusion assessment served as a control group after previous matching of baseline characteristics. All patients underwent routine periinterventional imaging via computed tomography (CT). Patients with common PV ostia were excluded from the analysis. Additionally, intraprocedural PV venograms were obtained before CB-PVI. In all cases a 28 mm CB was used. Procedural endpoint was demonstration of entry- and exit-block of all PVs. For pressure waveform analysis a pressure transducer was attached to the CB catheter enabling pressure recording from the catheter tip. The balloon catheter was then positioned inside the PVs and pressure recordings were analyzed. In sinus rhythm a typical atrial (A) and ventricular (V) pressure waveform can be observed. In AF a low amplitude V-wave can typically be observed. After balloon inflation positioning of the CB aiming at PV occlusion based on pressure waveform analysis was conducted. Loss of the A wave and amplitude increase of the V wave during sinus rhythm or an increase of the V wave during AF was observed at optimal occlusion. Ablation was conducted under live recordings of PV potentials by a circular mapping catheter inside the PVs in both groups. 

Results

The study group consisted of 30 patients (11 females, mean age 68.6±11.2 years, 42 % persistent AF). The control group consisted of 30 patients (10 females, mean age 64.2±8.1 years, 45 % persistent AF). A total of 240 PVs were targeted for PVI in both groups and could be isolated in all cases. In the study group 116 PVs were successfully isolated without the use of additionally venograms assessing for PV occlusion. All remaining PVs were successfully isolated after additional venograms. The mean procedure duration was 95±7 minutes in the study group and 89±21 minutes in the control group (p=0.14) with a mean fluoroscopy duration of 13.4±4.4 minutes in the study group and 11.1± 6.2 minutes in the control group (p=0.10). The mean contrast medium volume was 22±9 ml in the study group and 36±12 ml in the control group, which was significantly different (p=0.0001). Mean balloon temperatures and mean ablation application durations did not differ significantly between groups (Table 1). There were no periprocedural complications. 

Conclusion

CB-PVI utilizing pressure waveform analysis to assess PV occlusion is feasible and safe and significantly reduces the amount of contrast medium as compared to CBI-PVI using conventional venography without prolongation of the procedure duration. Further studies are needed to address the feasibility of pressure waveform-guided CB-PVI in patients without preprocedural imaging and in more complex left atrial anatomies such as common PV ostia.