In addition to the classical steroids, which have cholesterol as a precursor, there are steroids with 7-dehydrocholesterol as a precursor. This review describes the identification of these steroids, their biosynthesis and some aspects of their function. There are three classes of these compounds, distinguished by the number of their carbon atoms, 23, 24 and 25. Each class has a spiral steroid and is a phosphodiester. Up until these investigations, no spiral steroids or steroid phosphodiesters were known. There are at least 13 compounds of which six have been purified to near homogeneity. Each one has been characterized by its mass and proposed composition. They function by regulating the NaK-ATPase. Based on the tissues in which they have been detected, each class of compound seems to regulate a different isoform of the NaK-ATPase. This is an important site of endocrine regulation.

Introduction: Digitalis use in patients with severe heart failure is controversial. We assessed the effects of digitalis therapy on mortality in a large, observational study in recipients of cardiac resynchronization therapy (CRT). Methods: Consecutive patients receiving a CRT-defibrillator in three European tertiary referral centers were enrolled and followed for a median of 28 months. Digitalis use was assessed at the time of CRT implantation. Multivariate Cox-regression model and propensity score matching was used to determine all-cause mortality as primary endpoint. CRT-response (defined as improvement of ≥1 NYHA class), echocardiographic improvement (defined as improvement of LVEF of ≥ 5%), and ICD shocks were assessed as secondary endpoints. Results: The study comprised 552 CRT recipients with standard indications, including 219 patients (40%) treated with digitalis. Compared to patients without digitalis, they had more often atrial fibrillation, poorer LVEF and higher NYHA class (all p ≤ 0.002). Crude analysis of all-cause mortality demonstrated a similar relative risk of death for patients with and without digitalis (HR=1.14; 95% CI 0.88-1.5; p=0.40). After adjustment for independent predictors of mortality, digitalis therapy did not alter the risk for death (adjusted HR=1.04; 95% CI 0.75-1.45; p=0.82). Also, in comparison to 286 propensity score matched patients, mortality was not affected by digitalis intake (propensity adjusted HR=1.11; 95% CI 0.72-1.70; p=0.64). CRT response was predominant in digitalis non-users concerning both improvement of HF symptoms and LVEF (NYHA p<0.01; LVEF p<0.01) while patients on digitalis had more often ventricular tachyarrhythmias requiring ICD shock (p=0.01). Conclusions: Digitalis therapy had no effect on mortality but did negatively affect CRT response and susceptibility to ventricular arrhythmias requiring ICD shock treatment.

Spiral steroids (SS) are a newly discovered type of steroid. Originally, they were described as cardiotonic glycosides because they cross-reacted with digoxin-specific antibodies (Digoxin-Like-Materials-DLM). SS differ from the classical steroids in several ways: [a] they are steroid phosphodiester conjugates and displace digoxin from digoxin-specific antibodies, [b] in contrast to all other steroids, cholesterol is not a precursor, [c] SS have more than 21 carbon atoms; the extra atoms form a 5th ring which includes a lactone, [d] SS bind to NaK-ATPase in membranes rather than receptors in the nucleus. SS have been identified by HPLC- mass spectroscopy in extracts from mammals, birds, and oysters but were not detected in plant extracts. Overall, SS seem to be key components in regulating potassium electrolytes during pregnancy and its related diseases – specifically pre-eclampsia and necrotizing enterocolitis.