Sleep disordered breathing in patients with heart failure

Sleep disordered breathing (SDB) is a common co-morbidity in patients with heart failure(HF). Both its forms — central and obstructive sleep apnea — are highly prevalent in thispopulation. SDB fragments sleep, impairs life quality, worsens exercise tolerance, worsens HFand is an independent predictor of poor prognosis. Still, SDB remains largely undiagnosed.Therefore, early detection of SDB seems to be of primary importance, especially in the presenceof new diagnostic and therapeutic methods. Treatment with continuous positive airwaypressure (CPAP) increases left ventricular ejection fraction and stroke volume in virtually allHF patients with obstructive and in 50% with central sleep apnea. For those in whom centralsleep apnea is not suppressed by CPAP, a trial of adaptive servoventilation is recommended.Although no randomized, controlled trials have shown improvement in mortality, several observationalstudies have shown that effective treatment of both forms of sleep apnea with variouspositive airway pressure devices improves survival of HF patients. Currently, 2 large trials withnewer masked based therapies with adaptive servoventilation are in progress. This article isa brief overview of present knowledge, the pathophysiology, diagnostic approach and therapy ofSDB

Intravenous iron supplementation improves energy metabolism of exercising skeletal muscles without effect on either oxidative stress or inflammation in male patients with heart failure with reduced ejection fraction

Background: Skeletal muscle dysfunction is a feature of heart failure (HF). Iron deficiency (ID) is prevalent in patients with HF associated with exercise intolerance and poor quality of life. Intravenous iron in iron deficient patients with HF has attenuated HF symptoms, however the pathomechanisms remain unclear. The aim of study was to assess whether intravenous iron supplementation as compared to placebo improves energy metabolism of skeletal muscles in patients with HF. Methods: Men with heart failure with reduced ejection fraction (HFrEF) and ID were randomised in 1:1 ratio to either intravenous ferric carboxymaltose (IV FCM) or placebo. In vivo reduction of lactates by exercising skeletal muscles of forearm was analyzed. A change in lactate production between week 0 and 24 was considered as a primary endpoint of the  study. Results: There were two study arms: the placebo and the IV FCM (12 and 11 male patients with HFrEF). At baseline, there were no differences between these two study arms. IV FCM therapy as compared to placebo reduced the exertional production of lactates in exercising skeletal muscles. These effects were accompanied by a significant increase in both serum ferritin and transferrin saturation in the IV FCM arm which was not demonstrated in the placebo arm. Conclusions: Intravenous iron supplementation in iron deficient men with HFrEF improves the functioning of skeletal muscles via an improvement in energy metabolism in exercising skeletal muscles, limiting the contribution of anaerobic reactions generating ATP as reflected by a lower in vivo lactate production in exercising muscles in patients with repleted iron stores

Phrenic nerve stimulation in patients with central sleep apnea: a single‑center experience from pilot and pivotal trials evaluating the remedē System

Background: Patients with central sleep apnea (CSA) have recently been shown to have improved sleep metrics and quality of life (QoL) with phrenic nerve stimulation (PNS). Aims: The aim of this study was to report the results of a partnership between cardiology, sleep medicine, and electrophysiology in a single clinical center as well as the enrollment, implantation, and follow‑up experience demonstrating both the safety and efficacy of PNS. Methods: This analysis included data from the pilot and pivotal trials investigating the effect of PNS using an implantable transvenous system in patients with CSA. We present our experience and data on the enrollment processes, implantation feasibility and safety, sleep indices, and QoL at 6 and 12 months of follow‑up. Results: Between June 2010 and May 2015, cardiology patients were prescreened and 588 of them were sent for in‑home sleep test. Ninety‑six patients were referred for polysomnographic studies, and 33 were enrolled and had an implant attempt, with 31 successfully receiving an implant. The apnea–hypopnea index was reduced in the pilot trial (mean [SD] of 48.7 [15.5] events/h to 22.5 [13.2] events/h; P < 0.001) and in the pivotal trial (mean [SD] of 48.3 [18.8] events/h to 26.0 [21.9] events/h; P < 0.001). Improvement in QoL was also observed. Conclusions: We showed that PNS improved sleep metrics and QoL in patients with CSA, which is a result of multiple factors, including a comprehensive coordination between cardiology, sleep medicine, and electrophysiology. This ensures appropriate patient identification leading to safe implantation and full patient compliance during follow‑up visits