CARDIOPULMONARY EXERCISE TESTING AND ITS CORRELATION WITH ECHOCARDIOGRAPHIC FINDINGS IN PATIENTS WITH ARRHYTHMOGENIC CARDIOMYOPATHY

Introduction: Arrhythmogenic cardiomyopathy (ACM) is a primary myocardial disease characterized by myocyte loss, progressive fibrofatty tissue replacement, high arrhythmic burden and progressive heart failure, which may lead to referral for heart transplantation. Although cardiopulmonary exercise testing (CPET) is widely used for risk stratification and prognostic assessment in multiple forms of cardiomyopathy, evidence specific to ACM remains limited. Aim of the study: This study aimed to analyze CPET and echocardiographic parameters in patients with ACM, with the objective of identifying correlation between them, and to compare right-dominant versus biventricular phenotypes. Methods: CPET and echocardiographic data from ACM patients evaluated at the University Hospital of Padua between June 2018 and June 2025 were analyzed. Sixty-two patients met inclusion criteria. Based on echocardiographic parameters, patients were classified into right-dominant (FAC < 34%, LVEF > 45%) and biventricular phenotypes (FAC < 34% , LVEF < 45%). Left-dominant forms were excluded due to their limited number. Statistical analyses were performed using SPSS. Results: CPET variables showed significant correlations with echocardiographic findings. In multivariate linear regression, peak VO₂ was independently associated with lower LVEF and lower TAPSE/PAP ratio in the overall cohort. In the biventricular phenotype, the TAPSE/PAP ratio confirmed its role as a determinant of reduced peak VO₂, whereas in the right-dominant phenotype RAAi played a more prominent role. The VE/VCO₂ slope showed to be primarily driven by higher RAAi and lower S′ values across phenotypes, with a possible threshold effect of TAPSE/PAP. ROC analysis identified RAAi, S′, and TAPSE/PAP as the most accurate echocardiographic predictors of reduced ventilatory efficiency, and TAPSE/PAP together with LVEF as the strongest predictor of peak VO₂ %, with AUCs indicating moderate to good discriminative ability. The study confirmed the safety of CPET evaluation in this patient population. Conclusion: CPET parameters exhibited meaningful correlations with echocardiographic markers, according to phenotype. Evaluating RAAi, S′, and TAPSE/PAP during echocardiographic examination allow a more accurate characterization of disease status, therapeutic decisions-making and appropriate follow-up planning. In patients presenting with abnormal values of these parameters, CPET may help further define the degree of aerobic impairment and ventilatory inefficiency, enhancing a more comprehensive clinical assessment.