This Week in Cardiology — May 21, 2026

Welcome to This Week in Cardiology. This week we're covering 10 notable papers spanning critical care and resuscitation, new insights into cardiomyopathies and vascular disease, and a look at the future of therapy from the world of basic science. Let's dive in.

Critical Care and Resuscitation A major study in JAMA Cardiology this week challenges a widely adopted approach to in-hospital resuscitation [7]. Since 2018, many hospitals in the United States have adopted the Resuscitation Quality Improvement, or RQI, program to enhance CPR training. Investigators conducted a difference-in-differences analysis using the Get With The Guidelines-Resuscitation registry to see if adopting RQI was associated with better outcomes for in-hospital cardiac arrest.

The Study They matched 18 hospitals that adopted RQI between 2019 and 2021 with 107 control hospitals that did not. The matching was based on pre-intervention survival rates and annual case volume. The study included nearly 50,000 in-hospital cardiac arrests over a four-year period, spanning two years before and two years after RQI implementation.

Results The primary outcome was risk-standardized survival to hospital discharge. In the RQI hospitals, survival actually decreased from 25.3% before the intervention to 21.2% after. A similar decrease was seen in control hospitals, from 25.0% to 21.5%. The difference-in-differences analysis showed no significant association between RQI adoption and survival to discharge or return of spontaneous circulation. The authors conclude that a program focused solely on CPR delivery may not be sufficient to improve survival from in-hospital cardiac arrest.

This finding that a single intervention may not be enough highlights the importance of the entire system of care, a topic addressed by a new American Heart Association Scientific Statement in Circulation on appropriate patient selection for the Cardiac Intensive Care Unit, or CICU [6]. The statement notes that despite advances in care that have reduced the risk of life-threatening events for many conditions, some hospitals maintain historical admission practices. This results in low-acuity patients occupying high-resource CICU beds when they could be safely managed on a telemetry ward. The statement aims to provide much-needed guidance from an international society on contemporary CICU admission standards, proposing specific triage criteria for common cardiovascular conditions and outlining priorities for future research.

Cardiomyopathies and Specific Diagnoses Turning to cardiomyopathies, a large registry study in the Journal of the American College of Cardiology provides crucial new data on sex-based differences in dilated and arrhythmogenic cardiomyopathy [8]. Using data from the multicenter SHaRe registry, investigators analyzed over 3,400 patients.

Key Findings Overall, a 61% male predominance was found. However, this varied significantly by the specific gene involved. Truncating variants in TTN, the most common genetic cause, were significantly less common in females. Furthermore, among those with TTN truncating variants, males had an earlier age of disease onset, with a median age of 45 compared to 51 for females. Conversely, variants in DSP and a group of non-TTN sarcomeric genes were more common in females. The study also found that pediatric-onset disease is genetically distinct, more often caused by non-TTN sarcomeric variants, with onset peaking in infancy and adolescence. These findings support implementing age- and sex-informed surveillance strategies for patients and their families.

And while we refine our understanding of known genetic cardiomyopathies, a new Clinical Consensus Statement from the European Society of Cardiology, published in the European Journal of Heart Failure, urges clinicians to be more vigilant for a rare and often-overlooked condition: eosinophilic heart disease [4]. The expert panel emphasizes that heart involvement in eosinophilia carries substantial morbidity and mortality and is often diagnosed late. They note that peripheral blood eosinophilia may be absent in some patients, making tissue biopsy essential for diagnosis. The document's goal is to increase awareness, promote earlier diagnosis to prevent irreversible heart damage, and advocate for a multidisciplinary approach to management.

Ischemia, from the Microvasculature to the Environment In the realm of ischemic heart disease, a prospective registry from South Korea published in The Lancet provides important prognostic data on coronary microvascular dysfunction, or CMD [2]. The study enrolled over 1,000 patients referred for clinically indicated invasive coronary angiography and performed systematic physiological assessment. CMD was defined as a coronary flow reserve below 2.0 and an index of microcirculatory resistance of 25 or greater.

Results CMD was found in about 22% of patients who had obstructive epicardial coronary artery disease, and notably, in about 9% of patients who did not. At a median follow-up of 1.9 years, the primary composite endpoint of all-cause death, MI, repeat revascularization, or heart failure hospitalization occurred significantly more often in patients with CMD. The hazard ratio was 1.91, indicating that the presence of CMD was associated with a nearly doubled risk of adverse events. This study confirms that CMD is a common and prognostically important finding, whether or not obstructive epicardial disease is also present.

While that study focuses on the microvasculature, another paper looks at a macro-environmental risk factor. Published in Heart, researchers from the China-VHD registry investigated the impact of air pollution on patients with known valvular heart disease [1]. They linked clinical data from over 12,000 VHD patients to high-resolution data on ambient fine particulate matter, or PM2.5. After two years of follow-up, patients in the highest tertile of PM2.5 exposure had a 24% higher risk of the primary outcome—all-cause mortality or heart failure hospitalization—compared to those in the lowest tertile. Each increase in exposure equivalent to the interquartile range was associated with an 11% higher risk. These findings highlight that environmental factors like air pollution can play a significant role in the prognosis of patients with valvular heart disease.

Future Therapies from Basic Science Finally, we'll look at three papers that point to the future of cardiovascular therapy, starting at the translational and basic science level. First, in the European Heart Journal, a study explores a minimally invasive, acellular therapy for post-infarction repair [3]. Researchers developed a hydrogel loaded with microparticles containing stromal cell secretome, which they call RESCAT. In a porcine model of myocardial infarction, intrapericardial injection of RESCAT led to improved cardiac function, reduced infarct size, and enhanced cardiomyocyte cell-cycle activity compared to controls. This approach offers a potential off-the-shelf therapy that harnesses regenerative paracrine signals without the need for live cells.

Digging deeper into the molecular mechanisms of atherosclerosis, a paper in Circulation Research identifies a new target within macrophages [5]. The study shows that a protein called EHD1 is upregulated in both mouse and human atherosclerotic plaques. Deleting EHD1 in macrophage precursor cells in mice reduced atherosclerotic lesion size. Mechanistically, EHD1 appears to promote inflammation by enhancing signaling through TNF receptor 2 and also by stabilizing another protein called sortilin, which is a known risk factor for atherosclerosis. This work uncovers a novel role for membrane trafficking in macrophage function and suggests EHD1 as a potential therapeutic target.

And pushing the boundaries of the known proteome, a study in Cardiovascular Research identifies thousands of previously unannotated microproteins, or miPs, in endothelial cells [10]. Using a sophisticated proteo-genomic approach in both mice and human cells, the investigators found that the expression of these tiny proteins is significantly altered by inflammation and vascular disease. Some are even secreted and can be detected in human serum, with levels changing after cardiac damage. A functional screen showed that many of these newly discovered miPs are important for endothelial cell growth and viability, suggesting they could represent a vast, unexplored landscape of biomarkers and therapeutic targets in cardiovascular disease.

A Note on Research Methods Before we wrap up, a quick note for those interested in research methodology. A new Scientific Statement in Circulation from the American Heart Association provides best practices for conducting and interpreting observational comparative research [9]. As large healthcare databases become more common, so does this type of research. The statement provides a framework for investigators and consumers of research, emphasizing the importance of a pre-specified protocol, the use of causal diagrams to map out potential biases, and the concept of 'target trial emulation' to guide rational study design. It’s a valuable resource for critically appraising the non-randomized studies that increasingly inform our clinical practice.

Editor's Pick If you only have time for one paper this week, make it the study in JAMA Cardiology on the Resuscitation Quality Improvement program [7]. This is a critical, real-world evaluation of a widely implemented training system, and its negative finding forces us to reconsider whether programs focused solely on CPR delivery are sufficient to improve in-hospital cardiac arrest survival.

Clinical Bottom Line Here are the key takeaways from this week in Cardiology. First, in a large, matched cohort study from a United States registry, hospital adoption of the RQI program for CPR training was not associated with improved survival or ROSC for in-hospital cardiac arrest. Improving these outcomes likely requires a multi-faceted systems approach. Second, new data from The Lancet shows that coronary microvascular dysfunction is common in patients undergoing angiography and is associated with a nearly two-fold higher risk of adverse cardiovascular events, regardless of the presence of obstructive epicardial disease. Third, from JACC, we learn that genetic risk in dilated and arrhythmogenic cardiomyopathies differs by sex. TTN truncating variants are more common with earlier onset in males, while DSP and other sarcomeric variants are more common in females, supporting a more nuanced approach to screening and surveillance. Fourth, a study in Heart demonstrates that for patients with valvular heart disease, higher exposure to PM2.5 air pollution is a significant and independent risk factor for mortality and heart failure hospitalization. Finally, new statements from the AHA and ESC provide updated guidance on appropriate CICU triage to better allocate resources, and on the diagnosis and management of the often-missed eosinophilic heart disease.

That's your roundup for This Week in Cardiology. The full transcript and references are available on the episode page in your AudioScholar library. This is an AI-curated summary — for clinical decisions, always consult primary sources and current guidelines. See you next week.