6MWT Predicts Survival Better Than CPET in Patients with Stable Cardiomyopathy
Carlo Rostagno *
Dipartimento Area Critica Medico Chirurgica, Università di Firenze, Italy.
Vieri Boddi
Dipartimento Area Critica Medico Chirurgica, Università di Firenze, Italy.
Gian Franco Gensini
Dipartimento Area Critica Medico Chirurgica, Università di Firenze, Italy
*Author to whom correspondence should be addressed.
Abstract
Aims: The prognostic value of different clinical, echocardiographic and functional parameters was evaluated in clinically stable outpatients with heart failure due to idiopathic dilated cardiomyopathy (DCM).
Study Design: Observational prospective study.
Methodology: 56 patients suffering from idiopathic dilated cardiomyopathy in waiting list for heart transplantation (33 men and 23 women, mean age 56.4 years) and in clinical stable conditions for a minimum of 3 months underwent baseline clinical evaluation, echocardiogram, 6 minute walk test (6 MWT) and cardiopulmonary exercise test (CPET). They were followed for an average period of 26.5 months to assess event-free survival (death, heart transplantation).
Results: During follow-up period 23 patients died, 21 for cardiovascular causes. 4 patients underwent heart transplantation. Age and sex were not related to survival. We found a significant predictive value for 6MWTD (at 1 year event-free survival was 53% for a distance <300 m), but not for VO2 peak or respectively anaerobic threshold (AT). At multivariate analysis using Cox-stepwise regression model NYHA class, 6MWTD, left ventricular ejection fraction and left ventricular end diastolic diameter were independent prognostic markers of survival.
Conclusion: An advanced NYHA class, a higher LVEDD and a distance of < 300m at 6MWT are useful prognostic markers of event free survival in outpatients with stable DCM while CPET was not.
Keywords: Dilated cardiomyopathy, prognosis, functional evaluation, 6 minute walk test.