Behavior of coronary sinus oxygen saturation and cardiac output in systolic heart failure

Abstract

Abstract Background CRT implantation is indicated in advanced systolic heart failure (LV-EF < 35%) on optimal medical therapy and left bundle branch block with wide QRS complex (QRS > 150 ms). This study investigates the influence of different variables on venous saturation in the coronary sinus during HFrEF. Methods In this study, blood gas analyses (BGA) of patients undergoing CRT implantation were performed at our center. Patients with an electrophysiological study but without structural heart disease served as a control group. In all patients a BGA from the coronary sinus was performed. Arterial and central venous saturation were used to determine cardiac output (CO) according to Fick's principle. Oxygen uptake was calculated from body surface area and age. Results In total, the study population included 19 patients in the CRT and 18 patients in the control group. The median age of the CRT group was 75 years (54-87 years) and in the control group 58 years (36-81 years). In the CRT group 53% had ischaemic cardiomyopathy. The saturation in the coronary sinus was 30.3% in CRT patients and was therefore significantly lower than in the control group (40.0%, p = 0.02). However, CO at rest did not differ in both groups (CRT 6.8 L/min vs. control 7.4 L/min.). It was observed that the coronary sinus saturation was independent of CO and the genesis of heart failure. In contrast, QRS width before CRT implantation was negatively correlated with saturation in the coronary sinus (r = - 0.58, p = 0.01). Conclusion In patients with systolic heart failure and despite a normal CO, a decreased oxygen saturation in the coronary sinus at rest was found compared to cardiac healthy subjects. CS saturation correlates negatively with the width of the QRS complex. It is not dependent on age, LV function and the genesis of heart failure.