First in-human modified atrial septostomy combining radiofrequency ablation and balloon dilation.

Objective: Preclinical research suggests that the combined use of radiofrequency ablation and balloon dilation (CURB) could create stable interatrial communications without device implantation. This study examined the first in-human use of CURB for modified atrial septostomy in patients with severe pulmonary arterial hypertension (PAH).

Methods: Between July 2018 and October 2021, CURB was performed in 19 patients with severe PAH (age: 31.5±9.1 years; mean pulmonary artery pressure: 73 mm Hg (IQR: 66-92); pulmonary vascular resistance: 18.7 Wood units (IQR: 17.8-23.3)). Under guidance of intracardiac echocardiography and three-dimensional location system, (1) fossae ovalis was reconstructed and ablated point-by-point with radiofrequency; (2) then graded balloon dilation was performed after transseptal puncture and the optimal size was determined according to the level of arterial oxygen saturation (SatO); (3) radiofrequency ablation was repeated around the rims of the created fenestration. The interatrial fenestrations were followed-up serially.

Results: After CURB, the immediate fenestration size was 4.4 mm (IQR: 4.1-5.1) with intracardiac echocardiography, systolic aortic pressure increased by 10.2±6.9 mm Hg, cardiac index increased by 0.7±0.3 L/min/m and room-air resting SatO2 decreased by 6.2±1.9% (p<0.001). One patient experienced increased pericardiac effusion postoperatively; the others had no complications. On follow-up (median: 15.5 months), all interatrial communications were patent with stable size (intraclass correlation coefficient=0.96, 95%CI:0.89 to 0.99). The WHO functional class increased by 1 (IQR: 1-2) (p<0.001) with improvement of exercise capacity (+159.5 m, P<0.001).

Conclusion: The interatrial communications created with CURB in patients with severe PAH were stable and the mid-term outcomes were satisfactory.

Trial Registration Number: NCT03554330.