Early repolarization syndrome (ERS) is diagnosed in survivors of unexplained cardiac arrest (UCA) who exhibit a distinct ECG pattern of early repolarization (ER), defined as J-point elevation ≥0.1 mV in ≥2 contiguous inferolateral leads. UCA survivors without ER or another identifiable cause are classified as idiopathic ventricular fibrillation (IVF). This study evaluated long-term outcomes in ERS compared with IVF.

Resources for observational comparative research have expanded enormously in recent years to include very large sources of granular, routinely collected health care data and modern statistical, epidemiologic, and econometric techniques. This scientific statement provides an overview of best practices and analytic considerations in observational comparative studies from the perspective of investigators, sponsors, publishers, and consumers of observational research. Observational comparative research is a component of the research landscape that fulfills a role distinct from that of interventional studies in the evaluation of drugs, surgical procedures, medical devices, and health policies. Sources of systematic error (ie, bias) in observational comparative studies include selection bias, information bias, and confounding. Principles from statistical science and econometrics can potentially be used to make causal conclusions from observational data. Target trial emulation is a useful framework to guide the rational design and illuminate the limitations of observational studies. As with interventional research, a formal study protocol should be prepared before every observational study to enhance rigor, reduce data manipulation, and promote transparency of study reporting. Selection of the study data source is a key decision early in the design stage of a study, and should be chosen on the basis of concordance between the needs of the specific study question and the properties of the data set. We recommend the use of causal directed acyclic graphs to clearly specify the study exposure, end points, confounders, colliders, moderators, and mediators. Taken together, these recommendations promote rational design choices and cautious interpretation of the results of observational comparative studies.

Transvenous pacing is increasingly recognized as problematic in patients with prior or concomitant tricuspid valve intervention, owing to risks of leaflet interference, prosthetic dysfunction, and progression of tricuspid regurgitation. Leadless pacemakers offer a valve-sparing alternative; however, their safety and performance in structurally altered right heart anatomy remain incompletely defined. We conducted a systematic review to evaluate procedural feasibility, electrical performance, device-valve interaction, and clinical outcomes of leadless pacemaker implantation in patients undergoing surgical or transcatheter tricuspid valve interventions. Thirty-four studies comprising 272 patients were included, encompassing surgical repair, bioprosthetic replacement, valve-in-valve procedures, transcatheter edge-to-edge repair, and transcatheter tricuspid valve replacement. Leadless pacemakers were implanted via transfemoral, transjugular, or direct surgical approaches, achieving a procedural success rate of 99.3%. Electrical performance was consistently favorable, with stable capture thresholds, sensing amplitudes, and impedance during follow-up. Device-valve interaction was infrequent and generally manageable. Leadless pacemaker-related complications were rare (1.1%), with no device-related mortality. Within the included studies of patients undergoing surgical or transcatheter tricuspid valve interventions, no study demonstrated worsening tricuspid regurgitation attributable to the leadless pacemaker or its delivery system. Across a broad spectrum of complex tricuspid anatomies, leadless pacemakers demonstrated excellent feasibility, durable electrical performance, and a low complication profile, supporting their role as a valve-sparing pacing strategy in this population. These findings support leadless pacing in patients with prior tricuspid intervention, although prospective comparative data are required to define its role relative to alternative pacing modalities.

The best management of coronary artery disease in patients with severe aortic stenosis undergoing transcatheter aortic valve implantation (TAVI) is debated. We investigated the clinical impact of the residual extent of myocardium at risk in patients undergoing TAVI.

Permanent pacemaker (PPM) implantation after heart transplantation (HT) is common, but contemporary data regarding utilization, outcomes, and emerging pacing technologies are limited.

The clinical benefit of intensive LDL cholesterol (LDL-C) lowering with evolocumab in patients with prior percutaneous coronary intervention (PCI) but without a prior myocardial infarction (MI) is not established.

While angiography-derived fractional flow reserve (AngioFFR)- and intravascular ultrasound (IVUS)-guided percutaneous coronary intervention (PCI) yield similar outcomes, with AngioFFR associated with lower PCI rates, the relative clinical effectiveness of AngioFFR versus IVUS-guided PCI according to angiographic lesion characteristics remains unclear.

Heart failure is an increasingly common comorbidity among people with HIV infection, complicating care and heightening the vulnerability of this population to social adversity (SA). However, the impact of different SA domains on outcomes in this population remains poorly understood.

It has long been accepted that observational analyses have an important role in evaluating use patterns and assessing the safety of different treatments, including cardiovascular devices, in clinical practice. With the proliferation of large electronic databases, there has been increasing interest in using observational analyses to also examine the comparative effectiveness of devices. However, these analyses are often met with skepticism because of concerns about whether they can generate credible evidence about causal effects. This is in part a result of the difficulty in meeting the assumptions necessary to interpret observational associations as causal effects and of the wide variability in analytic rigor. In this review, we outline frameworks and review methods for using observational analyses to answer questions about the effectiveness and safety of cardiovascular devices. We highlight the target trial framework as a practical tool for guiding observational comparative effectiveness analyses. We illustrate how the framework allows investigators planning and conducting observational analyses to organize their activities as responses to 3 prompting questions. First, what is the research question of the study (ie, "What do we want?")? Second, what are the resources-including background knowledge, research concepts, principles and methods, and available data-that can be brought to bear on the research question (ie, "What do we have?")? And third, what specific steps should be taken to use the available resources to answer the research question (ie, "What do we do?")? We focus our exposition on the evaluation of cardiovascular devices, for which randomized trial data are often limited and there is a strong need for real-world evidence. In this setting, real-world evidence is usually derived from observational comparisons of the treatment of interest with relevant comparator groups using data captured during routine care. A principled approach to the planning and conduct of observational analyses can improve the quality of real-world evidence generation and ensure that the results of observational studies on medical devices can support meaningful conclusions about the risks and benefits of new devices.

Exhaled end-tidal carbon dioxide (EtCO2) trajectory is associated with out-of-hospital cardiac arrest (OHCA) outcomes. However, the minimum EtCO2 monitoring duration needed to discriminate return of spontaneous circulation (ROSC) from non-ROSC remains unknown. We sought to determine the EtCO2 trajectory observation time required to differentiate ROSC from non-ROSC patients.

The optimal transfusion strategy in patients with acute myocardial infarction (AMI) and anemia may be influenced by sex differences in pathophysiology and cardiovascular outcomes. The Myocardial Ischemia and Transfusion trial (MINT) randomized patients with AMI and anemia to restrictive or liberal transfusion thresholds, but sex-stratified outcomes remain undefined. The objective was to evaluate whether the clinical effect of restrictive versus liberal red blood cell transfusion strategies differs by sex in patients hospitalized with AMI and anemia.

Inhibition of proprotein convertase subtilisin/kexin type 9 (PCSK9) is an effective therapy for reducing low-density lipoprotein (LDL) cholesterol (LDL-C) in adults with hyperlipidemia, including heterozygous familial hypercholesterolemia, thereby lowering cardiovascular risk. Current PCSK9 inhibitors are injectable therapies; no oral small-molecule PCSK9 inhibitor has yet been approved.