Hemodynamic response to tilt test with impedance cardiography in patients with atrial fibrillation.

Abstract

Abstract Background Hemodynamic response during transition from supine to standing position in idiopathic atrial fibrillation (AF) is not completely understood. Objective This study aims to analyze the hemodynamic changes during the head-up tilt test in idiopathic AF patients. Methods We investigated the hemodynamic changes during the head-up tilt test with impedance cardiography in 40 AF patients (12 AF rhythm-AFr, and 28 sinus rhythm-AFsr) and 38 non-AF. Results Patients in AFr showed attenuated SVI drop after standing in comparison to AFsr and non-AF [ΔSVI in mL/m2: -1.3(-3.4 to 1.7) vs. -6.4(-17.3 to -0.1) vs. -11.8(-18.7 to -8.0), respectively, p < 0.001]. PVRI decreased in AFr, while increased in AFsr and non-AF [ΔPVRI in dyne.seg.m2/cm5: -477(-1148 to 82.5) vs. 131(-525 to 887) vs. 357(-29 to 681), respectively, p < 0.01]. AFr also showed higher HR and greater CI increase after standing compared to non-AF. Linear regression demonstrated negative relationship of ΔPVRI and ΔSVI, with significant difference between AF rhythm and sinus rhythm for slopes [-171(-228 to -113) vs. -46(-58 to -34), p < 0.0001] and intercepts [-727 (-1040 to -414) vs -217(-392 to -42), p < 0.05]. Conclusions the hemodynamic response to orthostatic challenge suggests differential adaptations of the autonomic nervous system between patients with AF rhythm and those reverted to sinus rhythm or healthy controls. The relationship between PVRI and SVI may be a therapeutic target in AF.