Prognostic value of cardiopulmonary exercise testing in Idiopathic Dilated Cardiomyopathy.

Background: Although cardiopulmonary exercise testing (CPET) is considered as an important tool in risk stratification of patients with heart failure (HF), prognostic data in the specific setting of Idiopathic Dilated Cardiomyopathy (iDCM) are still undetermined. The aim of the study was to test the prognostic value of CPET in a large cohort of iDCM patients.

Methods And Results: We analyzed 381 iDCM patients who consecutively performed CPET. The study end-point was a composite of cardiovascular death/urgent heart transplantation (CVD/HTx). In the overall population the average values of peak oxygen consumption (peak VO/kg) and percent-predicted peak VO (peak VO%) were 17.1±5.1ml/kg/min and 59±15%, respectively. Mean VE/VCO slope was 29.8±6.1. During a median follow-up of 47months (interquartile range 23-84), 83 patients experienced CVD/HTx. Peak VO% (Area Under the Curve [AUC] 0.74; 95% CI 0.71-0.85, p<0.001) and VE/VCO slope (AUC 0.78; 95% CI 0.74-0.84, p<0.001) were more accurate in predicting CVD/HTx compared to peak VO/kg (AUC 0.60; 95% CI 0.54-0.68, p=0.003) (p<0.001 for both comparisons). The most accurate threshold values for outcome prediction in our iDCM cohort were <60% for peak VO% and >29 for VE/VCO slope. At multivariable analysis peak VO% and VE/VCO slope were the strongest predictors of CVD/HTx, either as continuous and categorical variables, whereas peak VO/kg was not independently related with prognosis.

Conclusion: In a large population of iDCM patients peak VO% and VE/VCO slope emerged as the strongest prognostic CPET variables. Prospective studies will be necessary to confirm these data.