Reproducibility of a simple cardiac output response to stress test to diagnose and monitor heart failure in a primary care setting

Background We developed a simple non-invasive Cardiac Output Response to Stress (CORS) Test to improve diagnosis and monitoring of heart failure in primary care. Aim The aim of the present study was to assess test-retest reproducibility of the CORS test. Method Thirty-two healthy volunteers (age, 64±10, female n=18) were recruited. Cardiac output was measured continuously using bioreactance method in supine and standing position, and during a two 3-min stages of a step-exercise protocol (10 and 15 steps per minute) using a 15-cm height bench. The CORS test was performed twice i.e. Test 1 and Test 2. Results Cardiac output and stroke volume were not significantly different between the two tests at supine (6.2±1.4 versus 6.3±1.7 L/min, P = 0.84; 102±24 versus 108±32 ml/beat, P = 0.36), standing (5.7±2.1 versus 5.7±1.9 L/min, P = 0.99; 82±32 versus 83±29 ml/beat, P = 0.93), stage one step-exercise (8.5± 1.8 versus 8.2±1.9 L/min, P = 0.56; 104±26 versus 104±27 ml/beat, P = 0.99) and stage two step-exercise (9.9±1.7 versus 9.6±2.0 L/min, P = 0.51; 109±29 versus 111±26 ml/beat, P = 0.76). There was a significant positive relationship between Test 1 and Test 2 cardiac outputs (r=0.92, P Conclusion The CORS test demonstrates acceptable reproducibility and can potentially be used in primary care to identify and monitor heart failure.