RV IsoMax: Development of a web-based single-beat analysis tool for the determination of RV-PA coupling.

Background: Right ventricular (RV) function significantly associates with mortality in pulmonary hypertension. Single-beat methods allow for clinical estimates of max isovolumetric pressure (Pmax) but have not been widely adopted due to inter-user and inter-method variability and center specific implementation of methods. The study aim was to develop a web-based analysis single-beat analysis program that optimizes single-beat Pmax estimates while reducing inter-user variability. Methods: Participants with a right heart catheterization were retrospectively identified from The Ohio State University Pulmonary Hypertension Registry. Right ventricular waveforms were digitized. The single-beat analysis program, RV IsoMax, was developed in R/RShiny to semi-automatically estimate the maximum isovolumetric pressure (Pmax). RV IsoMax results were compared to the popular 2nd derivative single-beat method. Interclass correlation coefficients were calculated for interobserver and inter-method variability in Pmax estimates. Results: The RV IsoMax method was tested across the spectrum of PH in participants with PH (n=45) and without PH (n=10). For the RV IsoMax method, there was no significant bias in Pmax estimates between observers (intraclass correlation coefficient: 0.96). In an inter-method comparison, the 2nd derivative method significantly underestimated Pmax compared to RV IsoMax with a bias of 24 mmHg (intraclass correlation coefficient to 0.69). The variability between methods persists into end-systolic elastance (Ees) and RV-PA coupling (Ees/Ea). Conclusions: The interactive user interface of the RV IsoMax application allows the user to semi-automatically calculate and explore variability in Pmax estimates. Significant differences in Pmax estimates between single-beat methods indicate their cut-off values cannot be used interchangeably.