Clinical implications of right ventricular stroke work index in advanced stage heart failure

Objective: Right ventricular function has prognostic value in heart failure. This has been shown with various non-invasive parameters in many studies. Right ventricular systolic functions can be evaluated with invasive and non-invasive parameters. In our study, we aimed to investigate the relation of right ventricular stroke work index (RV SWI), an invasive hemodynamic parameter of right ventricle, with prognosis of heart failure, cardiac events and its role in planning of treatment desicions. Materials and methods: The study followed up 132 patients admitted to our hospital outpatient clinic between April 2011 - November 2012 with diagnosis of advanced stage heart failure, (104 male, 28 female and age 24-81 years). The files of patients were searched retrospectively and patients with diagnosis of advanced stage heart failure, consulted to outpatient clinic of cardiology for further treatment were detected. All patients? medical history, demographic characteristics, cardiovascular risk factors, comorbid illnesses, New York Heart Association functional class, echocardiographic evaluations and basal right heart catheterizations performed were detected. The relation of RV SWI values with ventricular assist device insertion, heart transplantation, cardiac resynchronisation therapy, rehospitalisation due to decompensation composite end-points and with mortality were evaluated. Advanced stage heart failure was defined as ejection fraction < 35% with symptoms and/or signs of heart failure. Results: During 20 months follow-up, mortality was observed in 18(13.6%) patients. The relation between RV SWI and mortality did not reach statistical significance (p=0.773). In patients who died, mean RV SWI value was 7.5±3.4 g/m2 /beat, those who survived had RV SWI mean value 8.0±3.4 g/m2 /beat. The left ventricular ejection fraction (p<0.001) and right ventricle systolic diameter (p<0.001) had statistically significant relation with mortality. Survival was observed in 114 patients. Among the survivers, 47(41.2%) had event-free survival and 67(58.7%) had cardiac events during their follow-up. In the event-free survival group, the RV SWI value was 9.1±3.9 g/m2 /beat, the group who had cardiac events had RV SWI value 7.2±2.8 g/m2 /beat. In patients who survived without cardiac events RV SWI value was significantly different from those who survived with cardiac events (p=0.003), indicating that decreased RV SWI is associated with increased cardiac event rates among patients with advanced stage heart failure. Mean RV SWI value in decompensated group was 6.1±2.5 g/m2 /beat, in those without decompensation end-point mean RV SWI value was 85±34 g/m2 /beat. Right ventricular stroke work index had statistically significant relation with cardiac decompensation (p<0.001). Conclusion: Right ventricular stroke work index is a predictor of event free survival among patients with advanced stage heart failure. Our study did not support RV SWI as single parameter of predictor of mortality. Deaths due to both cardiac and non-cardiac events had effect on this finding. Risk models consisting of invasive, non-invasive and clinical parameters should be developed for prediction of all-cause mortality in advanced stage heart failure. Key words: heart failure, right ventricular stroke work index, primary and secondary endpoints