Comparison of cardiac output estimates by echocardiography and bioreactance at rest and peak dobutamine stress test in heart failure patients with preserved ejection fraction

Purpose: To assess the agreement between cardiac output estimated by two-dimensional echocardiography and bioreactance methods at rest and during dobutamine stress test in heart failure patients with preserved left ventricular ejection fraction (HFpEF). Methods: Hemodynamic measurements were assessed in 20 stable HFpEF patients (12 females; aged 61 ± 7 years) using echocardiography and bioreactance methods during rest and dobutamine stress test at increment dosages of 5, 10, 15, and 20 μg/kg/min until maximal dose was achieved or symptoms and sign occurred, that is, chest pain, abnormal blood pressure elevation, breathlessness, ischemic changes, or arrhythmia. Results: Resting cardiac output and cardiac index estimated by bioreactance and echocardiography were not significantly different. At peak dobutamine stress test, cardiac output and cardiac index estimated by echocardiography and bioreactance were significantly different (7.06 ± 1.43 vs 5.71 ± 1.59 L/min, P <.01; and 4.27 ± 0.67 vs 3.43 ± 0.87 L/m ²/min; P <.01) due to the significant differences in stroke volume. There was a strong positive relationship between cardiac outputs obtained by the two methods at peak dobutamine stress (r =.79, P <.01). The mean difference (lower and upper limits of agreement) between bioreactance and echocardiography cardiac outputs at rest and peak dobutamine stress was −0.45 (1.71 to −2.62) L/min and −1.35 (0.60 to −3.31) L/min, respectively. Conclusion: Bioreactance and echocardiography methods provide different cardiac output values at rest and during stress thus cannot be used interchangeably. Ability to continuously monitor key hemodynamic variables such as cardiac output, stroke volume, and heart rate is the major advantage of bioreactance method.