What are the diagnostic criteria for sepsis-induced cardiomyopathy?

Diagnosis of Sepsis-Induced Cardiomyopathy

Bedside cardiac ultrasonography (BCU) is the gold standard for diagnosing sepsis-induced cardiomyopathy, which should be performed in all patients with sepsis to evaluate for signs of left and right ventricular dysfunction. 1

Definition and Clinical Context

Sepsis-induced cardiomyopathy (SIC) refers to cardiac dysfunction that occurs in the setting of sepsis, characterized by:

• Reversible myocardial dysfunction
• Systolic and/or diastolic left ventricular dysfunction
• Possible right ventricular dysfunction
• Absence of primary cardiac ischemia

This condition affects approximately 10-70% of sepsis patients, with significant implications for mortality and morbidity 2.

Diagnostic Approach

Primary Diagnostic Tool: Echocardiography

1. Timing of Echocardiography:

   • Perform BCU within 48 hours of sepsis diagnosis or at the time of initial catecholamine peak 3
   • Repeat echocardiography at 48-96 hours to assess for improvement, as SIC is typically reversible 3

2. Key Echocardiographic Findings:

   • Left Ventricular Assessment:

     • Decreased left ventricular ejection fraction (LVEF <50%) 1, 4
     • Systolic dysfunction (present in 50-60% of sepsis patients) 2
     • Diastolic dysfunction (early biomarker with prognostic significance) 2
     • Global longitudinal strain (GLS) abnormalities (more sensitive than LVEF) 4

   • Right Ventricular Assessment:

     • Right ventricular dysfunction (present in 50-55% of cases) 2
     • Isolated right ventricular dysfunction (present in 47% of cases) 2
     • RV:LV end-diastolic volume ratio changes 1

3. Views and Techniques:

   • Apical four-chamber view
   • Subcostal short-axis view (particularly for RV assessment) 1
   • Parasternal long-axis and short-axis views

Advanced Imaging (When Available)

• Cardiac MRI: Provides tissue characterization showing:
  • Increased T1 and T2 times in patients with impaired LVEF 3
  • Elevated extracellular volume values 3
  • Note: While sensitive, MRI has limited accessibility in ICU settings 2

Biomarkers

While not diagnostic on their own, these can support the diagnosis:

• Cardiac troponins (elevated in myocardial injury)
• B-type natriuretic peptide (BNP) or NT-proBNP (elevated in cardiac stress) 1
• Novel biomarkers under investigation:
  • Fibroblast growth factor-21 (FGF-21)
  • Growth differentiation factor-15 (GDF-15) 2

Diagnostic Algorithm

1. Initial Assessment:

   • Identify patients with sepsis according to current definitions
   • Look for clinical signs of cardiac dysfunction (hypotension, tachycardia, new murmurs)

2. First-line Diagnostic Test:

   • Perform bedside cardiac ultrasonography (BCU) 1
   • Measure LVEF, RV function, and when possible, global longitudinal strain

3. Diagnostic Criteria:

   • Definite SIC: Decreased LVEF (<50%) in a patient with sepsis without prior cardiac dysfunction 4
   • Probable SIC: Normal LVEF but impaired GLS in a septic patient 4
   • RV-predominant SIC: Normal LVEF but evidence of RV dysfunction 2

4. Follow-up Assessment:

   • Repeat echocardiography at 48-96 hours to document improvement 3
   • Monitor cardiac biomarkers (troponin, BNP/NT-proBNP)

Clinical Implications and Pitfalls

Prognostic Significance

• SIC is associated with increased 90-day mortality (67% vs. 29% in patients without SIC) 5
• Patients with SIC have 6.1 times higher odds of mortality at 90 days 5

Common Pitfalls to Avoid

1. Relying solely on LVEF: LVEF is load-dependent and may not accurately reflect intrinsic myocardial contractility in sepsis due to altered loading conditions 4

2. Missing diastolic dysfunction: Diastolic dysfunction can be present even with preserved LVEF 2

3. Overlooking right ventricular involvement: RV dysfunction is common and associated with worse prognosis 2

4. Single assessment: SIC is dynamic; repeated evaluations are essential to capture its evolution 4

5. Confusing with other cardiomyopathies: Takotsubo cardiomyopathy can present similarly and may coexist with SIC 1, 3

By following this diagnostic approach, clinicians can promptly identify sepsis-induced cardiomyopathy and initiate appropriate management strategies to improve outcomes in this high-risk patient population.