Jia Lissa
By Nicole Lou, Senior Staff Writer, MedPage Today
October 14, 2026
In the landscape of modern cardiology, few puzzles have proven as stubborn as the role of chronic inflammation in heart failure (HF). While medical science has mastered the art of managing fluid overload and optimizing cardiac output, a significant portion of patients remains trapped in a cycle of worsening health, even when adhering to strict guideline-directed medical therapy (GDMT).
New data from the POSEIDON registry, presented at the Heart Failure Society of America (HFSA) annual conference, has brought this "invisible enemy" into sharp focus. The findings suggest that U.S. patients are significantly more prone to systemic inflammation than their global counterparts, fueling a sense of urgency—and frustration—among clinicians searching for effective, targeted therapies.
The Core Findings: A Nation Under Fire
The POSEIDON study, the largest global registry tracking inflammation in patients with atherosclerotic cardiovascular disease (ASCVD) or heart failure, provides a sobering snapshot of the American patient population.
When researchers examined the subset of U.S. heart failure patients, they found that roughly half exhibited elevated high-sensitivity C-reactive protein (hsCRP) levels—a key biomarker for systemic inflammation defined in the study as ≥2 mg/L. The prevalence was strikingly consistent across phenotypes:
- HFpEF (Heart failure with preserved ejection fraction): 50.8%
- HFmrEF (Heart failure with mildly reduced ejection fraction): 44.7%
- HFrEF (Heart failure with reduced ejection fraction): 50.3%
These figures stand in stark contrast to the global POSEIDON cohort, which spanned 18 countries and reported significantly lower rates of inflammation (38.8% for HFpEF, 38.1% for HFmrEF, and 38.2% for HFrEF).
Marat Fudim, MD, MHS, of Duke University Medical Center, who presented the data, did not mince words. "Now, what does that mean? I don’t know how to address it, but all I can tell you is that we are very inflamed as a nation of HF patients," Fudim remarked. He pointed toward the "usual suspects"—obesity, diabetes, and chronic kidney disease (CKD)—as the primary drivers of this inflammatory state.
A Chronology of Disappointment: The Search for a Target
The history of anti-inflammatory drug development in cardiovascular medicine is, by most accounts, a "disappointing story." For decades, researchers have hypothesized that by quenching the body’s inflammatory response, they could mitigate the progression of heart disease. Yet, the path to a regulatory approval for such a drug has been littered with clinical trial failures.
The Rise and Fall of Targeted Inhibitors
The most recent chapter in this saga involved ziltivekimab, a potent interleukin (IL)-6 inhibitor. Following early preclinical promise, the drug was moved into major Phase III trials, specifically HERMES and ATHENA, which were designed to test the efficacy of IL-6 inhibition in heart failure patients with elevated hsCRP.
However, in September 2026, the developer, Novo Nordisk, abruptly announced that both trials were being halted due to futility. This decision followed earlier disappointment from the ZEUS trial, which failed to show that ziltivekimab could reduce major adverse cardiovascular events (MACE) in patients with ASCVD and CKD.
The "Neutral" Legacy
As session discussant Amanda Vest, MBBS, MPH, of the Cleveland Clinic, noted during the HFSA conference, the field is "tricky to navigate." She reminded attendees of a long, troubled history of studies attempting to target specific inflammatory pathways, most of which resulted in neutral or outright negative outcomes. This historical context has left many in the field with a sense of "stifled enthusiasm," as the biological rationale remains strong, but the clinical execution remains elusive.
Supporting Data: Dissecting the POSEIDON Registry
The POSEIDON registry is not merely a collection of numbers; it is a massive, prospective effort that enrolled 18,904 adults with ASCVD and/or heart failure between 2023 and 2025. The U.S. subset analyzed by Fudim’s team included 799 patients across the spectrum of ejection fractions.
The data reveals that elevated hsCRP is not an isolated phenomenon but is deeply interconnected with other markers of disease severity. In the study:
- Biomarker Correlation: Elevated hsCRP levels were consistently linked to higher levels of IL-6 and NT-proBNP (N-terminal pro-B-type natriuretic peptide) across all HF phenotypes.
- Clinical Indicators: While the study looked for unique traits in high-inflammation patients, there were few "red flags" other than a notable correlation with higher insulin use and increased diuretic requirements.
This suggests that inflammation is not a rare complication but rather a foundational element of the metabolic and cardiac dysfunction that defines heart failure in the modern American patient.
Official Perspectives: The Path Forward
If targeted, single-pathway inhibition—such as IL-6 suppression—is not the "silver bullet," where should clinicians and researchers turn?
A Shift Toward Broader Modulation
Dr. Fudim suggested that the future of anti-inflammatory therapy may lie in "broader" approaches that modulate the immune system through multiple pathways rather than a single, high-precision strike. He pointed specifically to GLP-1 receptor agonists, which have demonstrated profound cardiovascular benefits.
"GLPs reduce inflammation, but they do it differently," Fudim explained. "It’s going to be a whole array of inflammatory environments, not just IL-6. I would probably not put my money right on IL-6 again. I think that door has closed in this moment."
The "Double-Edged Sword" Warning
However, Fudim offered a significant cautionary note. The immune system is essential for survival; therefore, suppressing it indiscriminately carries significant risks. "If you have an agent that can target multiple pathways, you might be OK. But at the same time, be careful how much you suppress or interfere with the immune system. It was given to us for a reason."
Clinical Implications: What Should Physicians Do Today?
With no dedicated anti-inflammatory drug currently available for heart failure, how should a physician manage a patient with elevated hsCRP?
For now, the strategy remains "practical" rather than "pharmacological." Fudim emphasizes that hsCRP should be used as a "jumping board" to motivate patients. It provides a tangible metric that can justify aggressive lifestyle interventions.
- Lifestyle Optimization: Exercise, weight loss, and dietary changes remain the primary tools for lowering systemic inflammation.
- Addressing Comorbidities: Because obesity, diabetes, and CKD drive inflammation, clinicians must be more aggressive in managing these secondary conditions.
- Risk Stratification: hsCRP acts as a window into the patient’s risk category. Even if a direct anti-inflammatory drug is not available, identifying those with high residual inflammatory risk allows for closer monitoring and more tailored use of current guideline-directed therapies.
As the medical community digests the POSEIDON findings, the consensus is clear: the American heart failure population is uniquely inflamed. While the search for a miracle drug continues, the immediate path forward requires a more holistic integration of metabolic health and cardiovascular care. The "disappointing story" of anti-inflammatory drug development may have reached a temporary impasse, but the need for a solution has never been more evident. For the millions of Americans living with the daily burden of heart failure, the next breakthrough cannot come soon enough.
Lina Hope
