Volume-outcome relationship in balloon aortic valvuloplasty: results of a consecutive, patient-level data analysis from a Japanese nationwide multicentre registry (J-SHD)

Objective Transcatheter balloon aortic valvuloplasty (BAV) remains an important alternative treatment for severe, symptomatic aortic stenosis. With increasing numbers of BAVs being performed, the need for large-scale volume-outcome relationship assessments has become evident. Here, we aimed to explain such relationships by analysing consecutive, patient-level BAV data recorded in a prospective Japanese nationwide multicentre registry. Design Prospective study. Setting Data of 1920 BAVs performed in 200 Japanese hospitals from January 2015 to December 2019. Participants The mean patient age was 85 years, and 36.9% of procedures involved male patients. Methods The efficacy of BAV was assessed by reducing the mean transaortic valve gradient after the procedure. We also assessed in-hospital complication rates, including in-hospital death, bleeding, urgent surgery, distal embolism, vessel rupture and contrast-induced nephropathy. Based on the distribution of case volume (median 20, IQR 10-46), we divided the patients into high-volume (>= 20) and low-volume (<20) groups. In-hospital complication risk was assessed with adjustment by logistic regression modelling. Results Indications for BAV included palliative/destination (44.2%), bridge to transcatheter aortic valve replacement (34.5%), bridge to surgical aortic valve replacement (7.4%) and salvage (9.7%). Reduction of the mean transaortic valve gradient was similar between the high-volume and low-volume groups (20mm Hg vs 20mm Hg, p=0.12). The proportion of in-hospital complications during BAV was 4.2%, and the incidence of complications showed no difference between the high-volume and low-volume groups (4.2% vs 4.1%, p=1.00). Rather than hospital volume, salvage procedure was an independent predictor of in-hospital complications (OR, 4.04; 95% CI, 2.03 to 8.06; p<0.001). Conclusion The current study demonstrated that procedural outcomes of BAV were largely independent of its institutional volume.