Cardio-Kidney-Metabolic Syndrome: ACC CKM Staging & Management

Abstract

This article reviews the clinical implications of the Cardio-Kidney-Metabolic (CKM) Syndrome continuum, focusing on the 2023 American College of Cardiology (ACC) Expert Consensus Statement. 

CKM syndrome describes the profound, bidirectional interaction among cardiovascular disease, chronic kidney disease (CKD), and metabolic conditions, primarily Type 2 Diabetes (T2D) and obesity. 

The ACC introduced a novel four-stage classification system to standardize risk stratification and guide early, integrated management. Key management shifts emphasize the use of SGLT2 inhibitors and GLP-1 receptor agonists, agents proven to mitigate risk and improve outcomes across the CKM spectrum, independent of glycemic control.

Understanding and applying the CKM stages are essential for healthcare providers to implement a multidisciplinary approach, target therapy effectively, and reduce the high morbidity and mortality associated with these interconnected conditions in clinical practice.

Introduction: Defining the Cardio-Kidney-Metabolic (CKM) Continuum

The concept of the Cardio-Kidney-Metabolic (CKM) Syndrome represents a crucial evolution in the understanding of chronic disease management, moving away from siloed organ-specific treatments toward an integrated, systemic approach. 

Historically, diseases such as type 2 diabetes mellitus (T2D), chronic kidney disease (CKD), heart failure (HF), and atherosclerotic cardiovascular disease (ASCVD) have been managed by separate subspecialties. 

However, compelling clinical and mechanistic evidence underscores the profound, bidirectional interaction linking these conditions, where the presence of one significantly accelerates the progression of the others. This interconnectedness necessitates a unified management strategy.

Epidemiologic Burden and Clinical Imperative

The global prevalence of conditions within the CKM spectrum—particularly obesity and T2D—has reached epidemic proportions, driving a substantial increase in HF and CKD incidence. 

Data from international registries highlight that patients with overlapping CKM risk factors face the highest rates of morbidity, mortality, and healthcare resource utilization. 

This clinical reality demands a paradigm shift focused on early risk stratification and the implementation of therapies that provide simultaneous benefit across multiple organ systems, thereby addressing the root systemic disease rather than just its final organ manifestations.

Context of the ACC 2023 Expert Consensus

In response to this imperative, the 2023 ACC Expert Consensus Decision Pathway on the Evaluation and Management of Adults with CKM Syndrome established the CKM continuum as a unified clinical entity. 

This landmark document provides a framework to standardize the identification, staging, and therapeutic sequencing for these high-risk patients. The core contribution is a novel, action-oriented staging system designed to guide providers in selecting optimal, evidence-based interventions at the earliest appropriate stage, ensuring that patients receive maximum benefit from agents with proven cardiorenal-metabolic protective effects.

Pathophysiology: The Interconnected Feedback Loops

The Cardio-Kidney-Metabolic (CKM) Syndrome is underpinned by shared and mutually reinforcing pathophysiological pathways. This organ crosstalk creates a vicious cycle where dysfunction in one system accelerates damage in the others, leading to progressive multi-organ failure.

Shared Mechanisms: Insulin Resistance, Inflammation, and Fibrosis

Three fundamental processes drive the CKM continuum:

1. Insulin Resistance and Adipose Dysfunction: Excess visceral adipose tissue leads to lipotoxicity, ectopic fat deposition, and the release of pro-inflammatory adipokines. Insulin resistance is central, impairing glucose utilization and triggering compensatory hyperinsulinemia. This state promotes oxidative stress and endothelial dysfunction, directly preceding hypertension and atherosclerosis.
   
   
2. Chronic Systemic Inflammation: The metabolic milieu (hyperglycemia, dyslipidemia, adipokines) fosters a low-grade, persistent inflammatory state. Cytokines, such as IL-6 and TNF-alpha, contribute to endothelial damage, vascular stiffening, and myocardial remodeling, creating a fertile ground for ASCVD and HF development.
   
   
3. Renal Hemodynamics and Fibrosis: In the kidney, hyperglycemia and hypertension cause efferent arteriolar vasodilation and increased glomerular capillary pressure (glomerular hyperfiltration). Over time, this stress leads to podocyte injury, proteinuria, and the activation of the Renin-Angiotensin-Aldosterone System (RAAS), culminating in interstitial fibrosis and progressive decline in the estimated Glomerular Filtration Rate (eGFR).
   
   

Organ Crosstalk in CKM Syndrome

The reciprocal failure among the heart, kidneys, and metabolic system defines the CKM syndrome:

• Heart → Kidney: In heart failure (HF), reduced cardiac output and chronic venous congestion lead to renal hypoperfusion and increased intra-abdominal pressure, collectively impairing renal blood flow and GFR (cardiorenal syndrome Type 2).
  
  
• Kidney → Heart: CKD contributes to cardiovascular risk through multiple non-traditional factors, including anemia, hypervolemia, uremic toxins, mineral and bone disorders, and chronic volume overload, which directly drive left ventricular hypertrophy and HF progression.
  
  
• Metabolic → Cardiorenal: T2D and obesity directly induce microvascular damage, leading to albuminuria and nephropathy, while simultaneously promoting atherosclerosis and myocardial stiffness (HF with preserved ejection fraction, HFpEF).
  
  

This complex interplay validates the need for agents that simultaneously target these intertwined pathways, such as SGLT2 inhibitors and GLP-1 receptor agonists, which address both the metabolic drivers and the resultant organ damage.

Diagnosis and Risk Stratification: The ACC CKM Stages

The 2023 ACC Expert Consensus introduced a four-stage classification system for the Cardio-Kidney-Metabolic (CKM) Syndrome. This framework shifts clinical focus from treating established, symptomatic disease to proactive, staged prevention and risk reduction. The staging is crucial as it dictates the intensity of lifestyle modification, screening protocols, and the selection of evidence-based pharmacologic therapy.

Stage 1: At Risk (No Established Disease)

Stage 1 identifies individuals at increased risk due to traditional factors but without manifest cardiometabolic disease.

• Criteria: Presence of obesity (BMI ≥ 30 kg/m²), unhealthy diet, physical inactivity, or pre-hypertension.
  
  
• Focus: Intensive lifestyle modification (e.g., medical nutrition therapy, structured exercise), routine screening for the progression to Stage 2, and aggressive management of existing traditional risk factors (e.g., lipids).
  
  

Stage 2: Metabolic Disease

Stage 2 is characterized by the presence of a metabolic condition that initiates systemic organ damage, but without established cardiovascular or advanced kidney disease.

• Criteria: Manifest Type 2 Diabetes Mellitus (T2DM), established hypertension, or dyslipidemia requiring pharmacologic intervention.
  
  
• Focus: Implementation of cardioprotective pharmacotherapy. This is the critical stage for initiating agents like SGLT2 inhibitors and GLP-1 receptor agonists to prevent the transition to organ damage, independent of strict glycemic or blood pressure targets.
  
  

Stage 3: Early Organ Damage

Stage 3 marks the onset of subclinical or early-stage organ damage in either the heart or the kidneys, signifying high-risk progression.

• Criteria:
  • Kidney: Chronic Kidney Disease (CKD) Stage 3 (eGFR < 60 mL/min/1.73 m² or persistent macroalbuminuria/persistent albuminuria with eGFR > 60 mL/min/1.73 m²).
    
    
  • Heart: Established Atherosclerotic Cardiovascular Disease (ASCVD) (e.g., prior MI, stroke) or early Heart Failure (e.g., HFrEF or HFpEF with NT-proBNP elevation).
    
    
• Focus: Maximal use of Guideline-Directed Medical Therapy (GDMT) for both cardiac and renal protection, including dual or triple therapy with RAAS inhibitors, SGLT2 inhibitors, and GLP-1 RAs, as appropriate.
  
  

Stage 4: End-Stage CKM Disease

Stage 4 represents end-stage disease with manifest, complex multi-organ involvement, correlating with significantly reduced quality of life and high mortality.

• Criteria: End-Stage Kidney Disease (ESKD) requiring dialysis or transplant, refractory or advanced Heart Failure (Stage C/D), or multiple recurrent ASCVD events.
  
  
• Focus: Palliation, complex multi-specialty management, and assessment for advanced therapies (e.g., mechanical circulatory support, transplantation).
  
  

Key Diagnostic Biomarkers

Risk stratification relies on key biomarkers that reflect the activity and severity of organ crosstalk:

• Glycemic Status: HbA1c and fasting glucose.
  
  
• Kidney Health: Urine Albumin-to-Creatinine Ratio (UACR) and estimated Glomerular Filtration Rate (eGFR). UACR is a highly sensitive marker of early CKM damage.
  
  
• Cardiac Strain: Natriuretic Peptides (e.g., NT-proBNP/BNP), reflecting myocardial wall stress and volume status.
  
  

Evidence-Based Pharmacologic Management by CKM Stage

Pharmacologic management in the Cardio-Kidney-Metabolic (CKM) Syndrome is focused on early, integrated intervention, leveraging agents that provide pleiotropic benefits across the heart, kidney, and metabolic systems. The therapeutic strategy aligns directly with the ACC CKM staging to maximize organ protection.

Foundational Therapy: Lifestyle and Risk Factor Modification

For all patients, particularly those in CKM Stage 1, foundational management includes intensive lifestyle modification. This encompasses structured medical nutrition therapy, increased physical activity (≥ 150 minutes of moderate-intensity activity per week), and achieving optimal weight management. Aggressive control of traditional cardiovascular risk factors—including blood pressure (often targeting <130/80 mmHg), LDL-C reduction (targeting <70 mg/dL or lower depending on risk), and smoking cessation—remains paramount.

Stage-Specific Management: The Role of Novel Cardioprotective Agents

The key shift in CKM management is the early, preferential use of two drug classes—SGLT2 inhibitors and GLP-1 receptor agonists—due to their proven organ-protective effects independent of their glucose-lowering capabilities.

SGLT2 Inhibitors: Evidence from DAPA-HF, EMPA-KIDNEY, and EMPA-REG OUTCOME

Sodium-Glucose Cotransporter-2 (SGLT2) inhibitors are a Class I Recommendation for multiple CKM conditions, regardless of a diagnosis of Type 2 Diabetes. Their benefits extend to:

• Heart Failure: Trials such as DAPA-HF (dapagliflozin) and EMPEROR-Reduced (empagliflozin) demonstrated significant reductions in the composite outcome of cardiovascular death or heart failure hospitalization in patients with HFrEF (CKM Stage 3/4). Further, EMPEROR-Preserved showed benefit in HFpEF, extending this protection across the HF ejection fraction spectrum.
  
  
• Chronic Kidney Disease: The EMPA-KIDNEY and DAPA-CKD trials demonstrated a consistent reduction in the composite of CKD progression, ESKD, or renal death, confirming SGLT2 inhibitors as foundational therapy for CKD with or without diabetes, especially in patients with albuminuria. The proposed mechanism involves improving renal hemodynamics by reducing hyperfiltration and mitigating inflammation.
  
  
• ASCVD Prevention: The EMPA-REG OUTCOME trial established the benefit in reducing cardiovascular death and hospitalization in high-risk patients with established ASCVD and T2D.
  
  

GLP-1 Receptor Agonists: Cardiovascular and Weight Outcomes (SELECT Trial)

Glucagon-Like Peptide-1 (GLP-1) Receptor Agonists are increasingly recognized for their potent metabolic, cardiac, and renal benefits:

• ASCVD Risk Reduction: The SELECT trial (semaglutide) demonstrated a significant reduction in major adverse cardiovascular events (MACE) in patients with overweight/obesity but without prior diabetes, underscoring their primary cardiovascular benefit. Previous trials, including LEADER (liraglutide) and Harmony Outcomes (albiglutide), established MACE reduction in patients with T2D.
  
  
• Weight Management: GLP-1 RAs are highly effective in promoting sustained weight loss, directly addressing the foundational metabolic dysfunction in CKM Stage 1/2.
  
  
• Renal Outcomes: Several trials show favorable trends in reducing albuminuria and stabilizing eGFR decline, though cardiorenal benefits are primarily driven by SGLT2 inhibitors in this setting. GLP-1 RAs are particularly prioritized in CKM Stage 2/3 patients who require substantial weight reduction or have a higher burden of ASCVD.
  
  

The Role of RAAS Inhibitors, Statins, and Antiplatelet Therapy

These traditional agents remain critical elements of Guideline-Directed Medical Therapy (GDMT) within the CKM framework:

• RAAS Inhibitors (ACEi/ARBs): Essential for managing hypertension, heart failure, and slowing CKD progression by reducing glomerular pressure and proteinuria, particularly in Stage 3 CKD.
  
  
• Statins: Remain the cornerstone for primary and secondary prevention of ASCVD across all stages of CKM.
  
  
• Aspirin/Antiplatelets: Indicated for secondary ASCVD prevention (Stage 3/4) but generally not for primary prevention in Stage 1/2 unless indicated by a very high 10-year risk profile.
  
  

Clinical Practice Summary and Implications

The adoption of the ACC Cardio-Kidney-Metabolic (CKM) Syndrome framework mandates a fundamental change in clinical workflow, shifting from reactive management to proactive, integrated risk reduction. 

For healthcare professionals, the critical implication is the necessity for intensified screening and multidisciplinary collaboration to address the simultaneous progression of cardiorenal and metabolic risk.

The staging system provides a clear roadmap for early intervention. In CKM Stage 2 (Metabolic Disease), the therapeutic window is optimally open for initiating agents that modify the disease course. 

The robust evidence supporting SGLT2 inhibitors and GLP-1 receptor agonists in reducing composite MACE, heart failure hospitalizations, and renal composite endpoints means these agents are no longer reserved solely for advanced diabetes control, but are foundational for organ protection. 

Clinicians must screen all high-risk patients (obesity, T2D, hypertension) for early markers like albuminuria (UACR) and elevated NT-proBNP, even in the absence of overt symptoms.

Practice Highlights: Implementing CKM Pharmacotherapy

Research Directions and Future Therapies

Future research in CKM syndrome is focused on identifying novel biomarkers for earlier detection of subclinical myocardial and renal injury, potentially leading to a CKM Stage 0.

Additionally, the development and integration of newer therapeutic classes, such as non-steroidal Mineralocorticoid Receptor Antagonists (MRAs) and dual GIP/GLP-1 receptor agonists, offer promising avenues to further address the multifactorial pathogenesis, particularly chronic inflammation and fibrosis, thereby refining management for Stage 3 and 4 disease. 

Ongoing trials will further clarify optimal combination strategies and long-term effects on end-stage outcomes.