Why majority of heart failure with preserved ejection fraction randomized controlled trials fail? Part: I

Abstract

Today, heart failure with preserved ejection fraction (HFpEF) remains one of the toughest Gordian knots in cardiovascular medicine with no visible effective and acceptable therapies. Owing to the complexity, urgency, and gravity of the problem of HFpEF, the present article has been divided into two parts – Part I deals with the description of the problem, and in Part II, the authors suggest innovative methodologies to deal with the problem globally. All the while we have been searching for a size which fits HFpEF, a less understood complex syndrome due to maladaptive changes in structural, functional, and biochemical aspects of the myocyte. Inflammation appears to be the underlying string which weaves together nitrosative/oxidative stress, endothelial dysfunction, downregulation of nitric oxide (NO) bioavailability/NO-mediated signaling, impaired myocardial bioenergetics, disturbed calcium handling, and concentric hypertrophy. Most of the HF with reduced EF (HFrEF) randomized controlled trials (RCTs) are positive, while the majority of HFpEF RCTs are either neutral, borderline, or negative leading to a huge vacuum in the therapeutic space of HFpEF. While few understand the statistical complexity of RCTs, many pretend to do so. Endeavor has been made in the present article to make the underlying concepts loud and lucid without going into statistical complexities. Attempts are being made to negotiate this problem by adopting/experimenting with innovative designs, enrichment trials, adaptive trials, umbrella trials, basket trials, and machine learning-based trials leading to what may be termed as “precision medicine, precision diagnosis, and precision therapy.” We have compared two recent negative HFpEF RCT's (TOPCAT trial - Treatment of Preserved Cardiac Function Heart Failure with an Aldosterone Antagonist, INDIE trial - Inorganic Nitrite Delivery to Improve Exercise Capacity in HFpEF) with one positive HFrEF RCT (CASTLE AF trial - Catheter Ablation Versus Standard Conventional Treatment in Patients with Left Ventricular Dysfunction and Atrial Fibrillation), one negative HFrEF RCT (IRONOUT HF trial - Oral Iron Repletion Effects on Oxygen Uptake in Heart Failure), one positive HFmEF / HFpEF randomized, parallel-group, blinded, multicenter trial (REDUCE LAP-HF TRIAL Phase 2: A Study to Evaluate the DC Devices, Inc. IASD™ System II to REDUCE Elevated Left Atrial Pressure in Patients with Heart Failure), one positive HFmEF / HFpEF non-randomized, multicenter, open label, single arm study (REDUCE LAP-HF TRIAL Phase 1: A Study to Evaluate the DC Devices, Inc. IASD™ System II to REDUCE Elevated Left Atrial Pressure in Patients with Heart Failure) in order to understand why majority of HFpEF Clinical Trials fail.