What are the EKG changes and management strategies for suspected myocarditis?

EKG Changes and Management Strategies for Suspected Myocarditis

The most common EKG abnormalities in myocarditis include diffuse T-wave inversion, ST-segment elevation without reciprocal ST-segment depression, and prolongation of the QRS complex duration, which require prompt cardiology consultation and further cardiac imaging for diagnosis confirmation. 1

Characteristic EKG Findings in Myocarditis

• Sinus tachycardia associated with nonspecific ST/T-wave changes is the most common EKG abnormality 2
• ST-segment elevation without reciprocal ST depression (unlike in myocardial infarction) 1, 3
• Diffuse T-wave inversion across multiple leads 1, 4
• PR segment depression in both precordial and limb leads (suggesting perimyocarditis) 2
• PR segment elevation in aVR lead 2
• Prolongation of QRS complex duration (≥120 ms) - associated with worse prognosis 1, 4
• Pathological Q waves that may appear and disappear in a short period 3
• Low voltage QRS complexes (particularly in acute phase) 4, 3
• Various conduction abnormalities including AV blocks and bundle branch blocks 1

Prognostic EKG Markers in Myocarditis

• Ventricular tachycardia or fibrillation - indicates high risk 4
• High-degree atrioventricular block - independent predictor of fulminant myocarditis 4
• QRS duration ≥120 ms - associated with worse outcomes 2, 4
• Pathological Q waves - correlate with decreased left ventricular function 2, 3
• QRS/T angle ≥100° - poor prognostic indicator 2
• Prolonged QT interval - associated with adverse outcomes 2

Diagnostic Approach for Suspected Myocarditis

1. Initial Evaluation:

   • EKG - look for characteristic changes mentioned above 1
   • Cardiac troponin measurement (preferably high-sensitivity assay) 1
   • Echocardiogram to assess ventricular function and wall motion abnormalities 1

2. When to Suspect Myocarditis:

   • Presence of at least one symptom (chest pain, dyspnea, fatigue, palpitations, syncope) 1
   • At least one diagnostic criterion (EKG changes, elevated troponin, abnormal imaging) 1
   • Absence of significant coronary artery disease (stenosis <50%) 1

3. Further Cardiac Imaging:

   • Cardiac MRI is recommended for hemodynamically stable patients with suspected myocardial involvement 1
   • Look for myocardial edema, hyperemia/capillary leak (early gadolinium enhancement), and irreversible injury (late gadolinium enhancement) 1

Management Strategy for Suspected Myocarditis

1. Risk Stratification:

   • Patients with concerning EKG abnormalities, rising troponin, and/or echocardiographic abnormalities require cardiology consultation 1
   • Patients with high-risk features (hypotension, ventricular arrhythmias, advanced heart block) should be evaluated at an advanced heart failure center 1

2. Hospitalization and Monitoring:

   • All patients with acute myocarditis should be hospitalized for continuous EKG monitoring due to risk of malignant arrhythmias 5
   • Patients with chest pain as their only symptom, preserved LV function, and no ventricular arrhythmias may be managed in ambulatory setting with close monitoring 1

3. Specific Treatment Approaches:

   • For myocarditis associated with autoimmune diseases: consider methylprednisolone IV 1000 mg/day, followed by prednisone oral 1-2 mg/kg/day for 1-2 weeks 5
   • For fulminant myocarditis with refractory malignant ventricular arrhythmias: consider mechanical circulatory support 5
   • Endomyocardial biopsy should be considered in patients with clinical deterioration, particularly with heart block or ventricular arrhythmias when obstructive coronary disease has been excluded 1

Important Clinical Pearls

• EKG changes in myocarditis can mimic acute myocardial infarction, but the absence of reciprocal ST depression helps differentiate myocarditis 2, 3
• Up to 24.4% of patients with confirmed myocarditis may have a completely normal EKG, so absence of EKG changes does not rule out the diagnosis 6
• Serial EKGs are valuable as abnormal Q waves in myocarditis typically disappear within a short period, unlike in myocardial infarction 3
• The number of leads showing Q waves correlates inversely with left ventricular ejection fraction (r = -0.87) 3
• QRS abnormalities are associated with lower left ventricular ejection fraction and potentially worse prognosis 6