Letter: Beyond frame expansion: interpreting the implications of routine post-dilatation

We read with great interest the study by Husain et al1 and applaud the authors for this elegant and methodologically rigorous investigation. The authors combined benchtop and in vivo evaluations of routine “double-tap” post-dilatation at nominal volume following transcatheter aortic valve implantation with a balloon-expandable valve (BEV). Using a fluoroscopic calibration of valve commissural post height, they demonstrated that nominal-pressure reinflation increased frame expansion by approximately 9% across all SAPIEN 3 Ultra (Edwards Lifesciences) valve sizes, without excess procedural or 30-day adverse events1.

In a study from our group (Leone et al2), we evaluated a similar concept solely focusing on the 23 mm SAPIEN 3 Ultra, a size particularly susceptible to clinically relevant underexpansion and prosthesis-patient mismatch (PPM). Quantitative frame assessment was performed using pigtail-based fluoroscopic calibration, referencing the 10 mm spacing between radiopaque markers. This method provides a wider calibration baseline and minimises proportional measurement error compared with catheter width-based methods3. Nonetheless, this technique is inherently subject to interobserver variability, and unlike the commissural post height method, no correlation with computed tomography is available4. Distinct...