Screening and diagnosis

Classification and risk stratification

Perioperative care

Quality improvement

Patient education

Nonpharmacologic interventions

Therapeutic procedures

Respiratory support

Follow-up and surveillance

Specific circumstances

Preventative measures

Medical management

Surgical interventions

Inpatient care

Diagnostic procedures

Diagnostic investigations

Insufficient evidence to make a recommendation.

Strongly favor this test or intervention.

The Lake Louise criteria provides a diagnostic framework for evaluating myocarditis using MRI by considering three distinct imaging findings. Each identified finding is assessed with a binary response, either present (true) or absent (false), and is assigned a score.

The combined score, ranging from 0 to 3, provides a concise interpretation of potential myocardial inflammation or injury. The three MRI criteria evaluated are:

- **Regional or global myocardial signal intensity increase in T2-weighted images:** If present, this contributes 1 point to the total score.
- **Increased global myocardial early gadolinium enhancement ratio between myocardium and skeletal muscle in gadolinium-enhanced T1-weighted images:** This finding also adds 1 point if present.
- **At least one focal lesion with a non-ischemic regional distribution in inversion recovery-prepared gadolinium-enhanced T1-weighted images (late gadolinium enhancement):** Similarly, a true response here adds 1 point to the total.

These criteria aim to capture the complexity of myocarditis through reliable and measurable imaging changes. The summed score facilitates the interpretation as follows:

- **Score 0:** This suggests repeating the MRI in 1-2 weeks if initial results are negative yet there is a significant clinical suspicion of myocardial inflammation.
- **Score 1:** Indicates a need to consider a follow-up MRI within 1-2 weeks to confirm or exclude myocarditis.
- **Score 2:** Represents findings consistent with myocardial inflammation, implying the presence of an active inflammatory process affecting the myocardium.
- **Score 3:** Denotes MRI evidence of myocyte injury and/or scarring attributed to myocardial inflammation, indicating potential past or ongoing tissue damage.

Each step in this diagnostic process emphasizes using the MRI findings to drive clinical decision-making and adaptation of patient management strategies.

The Lake Louise Criteria for Magnetic Resonance Imaging Diagnosis of Myocarditis is a diagnostic tool used specifically in the field of cardiology. This calculator is applied to patients suspected of having myocarditis, an inflammation of the heart muscle. The Lake Louise Criteria utilizes cardiac magnetic resonance imaging (MRI) findings to aid in the diagnosis of myocarditis. 

The clinical utility of this calculator lies in its ability to provide a standardized approach to the interpretation of cardiac MRI findings in suspected myocarditis, thereby aiding in the accurate diagnosis and subsequent management of this condition. 

Exclusion criteria for the use of the Lake Louise Criteria include patients who are contraindicated for MRI such as those with certain types of implanted medical devices (e.g., certain pacemakers or neurostimulators), severe kidney disease, or claustrophobia. Additionally, it may not be applicable in cases where myocarditis is not the primary differential diagnosis.

Lake Louise criteria for magnetic resonance imaging diagnosis of myocarditis

The calculator categorizes the severity of heart failure using the New York Heart Association (NYHA) functional classification system. It does this by analyzing a patient's reported physical abilities related to cardiac disease and matches them to one of the four NYHA classes.

Here's the breakdown of each class:

- Class I involves patients who have cardiac disease but do not experience any limitations in physical activity. Regular activities do not cause undue fatigue, palpitation, or shortness of breath.
  
- Class II fits patients who have a slight limitation in physical activity due to cardiac disease. They feel comfortable when at rest, but ordinary physical activities might lead to fatigue, palpitation, or breathlessness.
  
- Class III describes patients with a marked limitation in physical activity. These individuals are comfortable when resting, but even less than ordinary activities cause fatigue, palpitations, breathlessness, or chest pain.
  
- Class IV covers patients who cannot engage in any physical activity without experiencing discomfort. They exhibit symptoms of heart failure even when at rest, and any physical activity worsens these symptoms.

To determine the appropriate class for a patient, the calculator compares the user’s description of their physical ability with these four established patterns. Each condition is linked specifically to one of the NYHA classes, providing a clear pathway from symptom description to classification. For example, if a patient’s physical condition matches the criteria for Class I, then the result is "Class I." This comparison method efficiently identifies the level of heart failure severity based on self-reported abilities and symptoms.

The NYHA functional classification for heart failure, or New York Heart Association Functional Classification, is a scoring system used to quantify the severity of symptoms in patients with heart failure. This classification system is applicable to patients diagnosed with heart failure and is used to assess their functional capacity and limitations during physical activity. 

The NYHA classification is divided into four classes: Class I (no symptoms and no limitation in ordinary physical activity), Class II (mild symptoms and slight limitation during ordinary activity), Class III (marked limitation in activity due to symptoms, even during less-than-ordinary activity), and Class IV (severe limitations, experiences symptoms even while at rest).

The clinical utility of this calculator is to guide treatment decisions, assess prognosis, and evaluate the effectiveness of therapeutic interventions in patients with heart failure. It is also commonly used in clinical trials to stratify patients and measure outcomes. 

There are no specific exclusion criteria for its use, but it is subjective and relies on patient self-report, so it may not be as accurate in patients with cognitive impairment or communication difficulties.

NYHA functional classification for heart failure

Myocarditis

Immunosuppressive therapy

Magnetic resonance imaging

Pediatric patients

Pediatric patients, evaluation

Patients with eosinophilic myocarditis

Patients with immune checkpoint inhibitor-induced myocarditis

Patients with immune checkpoint inhibitor-induced myocarditis, evaluation

As per EHA/ESC/ESTRO/IC-OS 2022 guidelines, 

Management of cardiac arrhythmias

Management of cardiac arrhythmias, ICD implantation

Antiviral therapy

Management of cardiac arrhythmias (cardiac pacing)

Clinical and imaging follow-up

Physical activity restrictions

Pediatric patients, immunosuppressive therapy

Management of cardiac arrhythmias (sedation)

Patients with immune checkpoint inhibitor-induced myocarditis, restarting ICI therapy

Patients with giant cell myocarditis

Patients with giant cell myocarditis (heart transplantation)

Management of heart failure

Management of HF

Patients with giant cell myocarditis, immunosuppressive therapy

Management of fulminant myocarditis

Management of fulminant myocarditis (circulatory support)

Management of cardiac arrhythmias (catheter ablation)

Setting of care

Transthoracic echocardiogram

Management of cardiac arrhythmias (antiarrhythmic drugs)

Pediatric patients, advanced cardiac life support

Management of cardiac arrhythmias (ECMO)

Electrocardiogram

Patients with giant cell myocarditis, management of cardiac arrhythmia

Laboratory tests

Laboratory tests, cardiac biomarkers

Management of cardiac arrhythmias (general principles)

Laboratory tests, inflammatory markers

Endomyocardial biopsy

Return to sport activities

Laboratory tests, serology

Diagnosis

Coronary angiography

Neonatal patients

Neonatal patients (management)

Neonatal patients (evaluation)

Heart transplantation

History and physical examination

Endomyocardial biopsy follow-up

Nuclear imaging

Management of fulminant myocarditis (inotropic support)

Pediatric patients (patients with vasculitides)

As per SHARE initiative 2019 guidelines, 

Patients with immune checkpoint inhibitor-induced myocarditis, management

Patients with myopericarditis

Laboratory tests (metabolic panel)

Myocarditis

Guidelines

Key sources