What is the initial approach to managing a patient with myocarditis and Acute Kidney Injury (AKI) due to an infection?

Initial Management of Myocarditis with Acute Kidney Injury Due to Infection

Immediately hospitalize the patient at an advanced heart failure center, perform urgent cardiac evaluation with ECG, high-sensitivity cardiac troponin, and echocardiogram, obtain cardiology consultation, and initiate supportive care with careful fluid management while treating the underlying infection. 1, 2

Immediate Diagnostic Workup

Upon presentation, the following tests must be obtained urgently:

• ECG to identify concerning abnormalities including diffuse T-wave inversion, ST-segment elevation without reciprocal depression, prolonged QRS duration, or complete/advanced atrioventricular block 1
• High-sensitivity cardiac troponin measurement, as elevated troponin indicates higher risk of adverse outcomes and warrants closer monitoring 1
• Transthoracic echocardiogram to assess ventricular wall motion abnormalities (often in noncoronary distribution), ventricular strain, and left ventricular systolic function 1
• Renal function assessment including creatinine and urine output to stage AKI severity, as AKI stage 3 is an independent predictor of in-hospital mortality in myocarditis 3

Risk Stratification and Level of Care

Patients with rising troponin and ECG or echocardiographic abnormalities concerning for myocarditis require immediate cardiology consultation. 1

The severity determines the appropriate level of care:

• Fulminant myocarditis (hypotension, cardiogenic shock, sustained ventricular arrhythmias, or advanced AV block) requires management at centers with expertise in advanced heart failure, mechanical circulatory support, and transplant capabilities 1, 2
• Mild to moderate myocarditis requires hospitalization ideally at an advanced heart failure center 1, 2
• Hemodynamically unstable patients or those with high-risk features require evaluation at an advanced heart failure center 1

Cardiac Monitoring and Arrhythmia Management

Temporary pacemaker insertion is indicated for symptomatic bradycardia and/or heart block during acute myocarditis. 1

Key monitoring considerations:

• Continuous cardiac monitoring for ventricular arrhythmias and conduction abnormalities 1, 2
• Patients with complete/advanced AV block and narrow QRS may improve with temporary pacing alone without requiring ECMO 4
• Wide QRS complexes (≥0.12 ms) with ST-segment changes indicate higher likelihood of requiring ECMO support 4
• Antiarrhythmic therapy can be useful for symptomatic NSVT or sustained VT during the acute phase 1

Fluid Management in the Setting of AKI

Careful fluid management is critical as both inadequate and excessive fluid administration can worsen outcomes, particularly in patients with concurrent myocarditis and AKI. 5

Fluid management strategy:

• Administer initial fluid bolus of 20 mL/kg if shock is present, with subsequent frequent reassessment 5
• Monitor closely for signs of fluid overload given impaired cardiac function and reduced renal clearance 5
• Reassess frequently after fluid administration to detect deterioration at an early stage 5

Pharmacological Management

Initiate guideline-directed medical therapy for heart failure before discharge and titrate in the outpatient setting. 1, 2

Specific pharmacological considerations:

• Low-dose aldosterone system inhibitors may be used empirically in patients with mildly reduced LV systolic function and stable hemodynamics 2, 5
• Beta-blockers may be helpful for supraventricular arrhythmias if hemodynamically stable, but avoid in hemodynamically compromised patients as they can precipitate cardiogenic shock 2, 5
• NSAIDs should generally be avoided in isolated myocarditis due to risk of increased inflammation and mortality, but may be used for associated pericardial involvement 2, 5
• Low-dose colchicine or prednisone may be added for persistent chest pain with pericardial involvement, with tapering based on symptoms 2, 5

Immunosuppressive Therapy Considerations

Intravenous corticosteroids may be considered in patients with hemodynamic compromise or multisystem inflammatory state, balanced against infection risk. 1, 2, 5

Specific indications:

• Empiric corticosteroids may be considered in fulminant myocarditis with biopsy evidence of severe myocardial inflammatory infiltrates 1, 2
• Immunosuppression is recommended for giant cell myocarditis, cardiac sarcoidosis, and eosinophilic myocarditis 2, 6
• Do not use empiric immunosuppression for typical lymphocytic viral myocarditis, as it has not demonstrated benefit and increases infection risk 2, 6

Advanced Cardiac Imaging

Cardiac MRI is recommended if the patient is hemodynamically stable to confirm myocardial inflammation and exclude ischemia. 1

CMR considerations:

• CMR is the most sensitive method to exclude ischemia and preexisting cardiomyopathies while confirming myocardial inflammation, nonischemic epicardial scar, and pericardial effusion 1
• Endomyocardial biopsy should be considered in patients with clinical deterioration, particularly if heart block or ventricular arrhythmias are present and obstructive CAD has been excluded 1

Mechanical Circulatory Support

For patients developing cardiogenic shock despite optimal medical management, mechanical circulatory support may be required. 2, 6

MCS considerations:

• ECMO should be promptly introduced in patients with wide QRS complexes with ST-segment changes who develop hemodynamic instability 4
• Approximately 2% to 9% of patients require inotropic agents or mechanical circulatory devices 6
• Patients requiring mechanical support have approximately 28% rate of mortality or heart transplant at 60 days 6

Prognostic Factors

AKI stage 3 and elevated SOFA score are independent predictors of in-hospital mortality in acute myocarditis. 3

Key prognostic considerations:

• The risk of in-hospital mortality is highest among patients in AKI stage 3 with high SOFA score 3
• Approximately 59% of myocarditis patients develop AKI within 48 hours of hospitalization 3
• Uncomplicated myocarditis has approximately 0% mortality, while myocarditis complicated by acute heart failure or ventricular arrhythmias has 12% rate of in-hospital mortality or need for transplant 6

Activity Restriction

Competitive sport participation and strenuous physical activity must be avoided for 3-6 months after diagnosis. 2, 5

Follow-Up Surveillance

Follow-up testing including ECG, echocardiogram, ambulatory rhythm monitor, and CMR is recommended 3-6 months after presentation. 2, 5

Critical Pitfalls to Avoid

• Do not delay cardiac evaluation due to focus on infection or renal failure, as myocarditis requires urgent cardiac-specific management 7
• Do not initiate beta-blockers in hemodynamically compromised patients, as they can precipitate cardiogenic shock 2, 5
• Do not use NSAIDs routinely in isolated myocarditis without pericardial involvement due to increased inflammation risk 2
• Do not allow early return to exercise before the 3-6 month restriction period and proper reassessment 2
• Do not use empiric immunosuppression for typical viral myocarditis, as it increases infection risk without proven benefit 2, 6