ABC | Volume 114, Nº3, March 2020

Original Article Software for Post-Processing Analysis of Strain Curves: The D-Station Rafael Duarte de Sousa, 1 Carlos Danilo Miranda Regis, 1 Ittalo dos Santos Silva, 1 Paulo Szewierenko, 2 Renato de Aguiar Hortegal, 3, 4 Henry Abensur 4 Instituto Federal de Educação, Ciência e Tecnologia da Paraíba, 1 João Pessoa, PB – Brazil Instituto Dante Pazzanese de Cardiologia - Statistical Consultant, 2 São Paulo, SP – Brazil Instituto Dante Pazzanese de Cardiologia, 3 São Paulo, SP – Brazil Hospital Beneficência Portuguesa de São Paulo – Echocardiography Department, 4 São Paulo, SP – Brazil Mailing Address: Renato de Aguiar Hortegal • Hospital Beneficência Portuguesa de São Paulo. Setor de Ecocardiografia. Rua Maestro Cardim 769. CEP 01323-001, Bela Vista, SP – Brazil E-mail: eletrocardio2009@gmail.com Manuscript ereceived December 11, 2018, revised manuscript April 25, 2019, accepted May 15, 2019 DOI: https://doi.org/10.36660/abc.20180403 Abstract Background: The use of speckle-tracking echocardiography for evaluation of cardiac function has great applicability in different scenarios. The broad use of this method requires tools that allow the extraction of relevant data from strain curves and inclusion of these data in traditionally used parameters. Objectives: The present study aimed to present and validate a free software, called D-station, for analysis of strain curves. Methods: From raw data files, the D-Station determines the phases of the cardiac cycle, and simultaneously exhibits the strain and strain rate curves of different cardiac chambers. Validation of the software was done by global longitudinal strain (GLS), and the analyses were performed: 1) graphical comparison of EchoPAC and D-Station paired measurements in relation to equality line; 2) by coefficient of correlation of these measurements; 3) test of hypothesis (p > 0.05); and 4) Bland-Altman analysis. Results: The Spearman’s rho correlation coefficient indicated a strong correlation between the measurements. Results of the test of hypothesis showed a p-value = 0.6798 >> 0.05, thus also indicating an equivalence between the softwares. The Bland-Altman analysis revealed a bias ≤ 1% and dispersion ≤ 2% between the measurements. The tests showed that, for GLS values lower than 10%, there was a trend for higher percentage difference between the values, although the absolute values remained low. Conclusion: The D-Station software was validated as an additional tool to the EchoPAC, which uses the raw data from the strain and strain rate curves exported from a proprietary software. (Arq Bras Cardiol. 2020; 114(3):496-506) Keywords: Cardiovascular Diseases/diagnostic imaging; Prognosis; Echocardiography/methods; Ventricular Dysfunction, Left/physiopathology; Speckle Tracking. Introduction Analysis of cardiac strainby speckle tracking echocardiography has great applicability in different scenarios, including clinical cardiology practice 1 and research, 2 providing information about local and global mechanics of cardiac chambers. Although left ventricular global longitudinal strain (GLS) is a robust parameter of cardiac function, 1-3 it assesses cardiac strain between the onset of isovolumetric contraction and the end of ventricular ejection. Therefore, valuable information of other phases, like isovolumetric relaxation, is not measured by the GLS. Therefore, other tools are needed to obtain relevant data from the strain curve that can be used as additional methods to currently used ones. Most of offline softwares supplied by different manufacturers (proprietary softwares) has preset analysis modes and parameters of cardiac strain. If on the one hand, this can make the software simpler and user-friendlier in daily clinical practice, on the other, makes it difficult to use this technology in research. In addition, the access to these tools may be limited and expensive. International reference centers for study on cardiac strain usually have customized softwares that allow offline processing, without exclusive rights established by the manufacturers, and adjustments to their needs. 4 The present study aims demonstrate the use of a new, free software called D-station, as an additional tool for the analysis of strain curves provided by any proprietary software. Besides, the study aims to validate this new software by comparison of its GLS values with GLS values obtained by the EchoPAC (GE) software. Methods D-Station: post-processing software for strain curve analysis D-Station is a free, customized software written in Python 3, designed to enable an offline post-processing of the strain curves. The steps of execution of D-Station 496