BackgroundWe developed a simple non-invasive Cardiac Output Response to Stress (CORS) Test to improve diagnosis and monitoring of heart failure in primary care.AimThe aim of the present study was to assess test-retest reproducibility of the CORS test.MethodThirty-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.ResultsCardiac 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<0.01 with coefficient of variation of 7.1%). The mean difference in cardiac output (with upper and lower limits of agreement) between Test 1 and Test 2 was 0.1 (−1.9 to 2.1) L/min, combining rest and exercise data.ConclusionThe CORS test demonstrates acceptable reproducibility and can potentially be used in primary care to identify and monitor heart failure.
Quantification of the Impaired Cardiac Output Response to Exercise in Heart Failure: Application of a Non-Invasive Device