From the Guidelines
Influenza infection is associated with myocarditis, a condition that can lead to serious cardiac complications if not promptly diagnosed and treated. According to the study by 1, influenza infection has been linked to various complications, including myocarditis and pericarditis. The presentation of influenza-associated myocarditis can vary, but common symptoms include:
- Chest pain
- Shortness of breath
- Fatigue
- Palpitations
- Fever Diagnosis involves a combination of clinical evaluation, laboratory tests, such as cardiac biomarkers like troponin and BNP, electrocardiogram (ECG), echocardiography, and occasionally cardiac MRI. Treatment primarily consists of supportive care, including bed rest, monitoring, and management of heart failure if present, as well as antiviral medications like oseltamivir (Tamiflu) 75mg twice daily for 5 days, which should be started as soon as possible if influenza is suspected or confirmed, ideally within 48 hours of symptom onset. In severe cases, inotropic support, mechanical ventilation, or even mechanical circulatory support may be necessary. Annual influenza vaccination is recommended as prevention, especially for those with underlying heart conditions, to reduce the risk of myocarditis and other cardiac complications associated with influenza infection. The underlying mechanism involves both direct viral invasion of cardiac myocytes and the body's inflammatory response to the infection, highlighting the importance of prompt treatment and prevention measures. Most patients recover completely with appropriate treatment, though some may develop long-term cardiac complications, emphasizing the need for close monitoring and follow-up care.
From the Research
Influenza Infection and Myocarditis
- Influenza infection is associated with myocarditis, a condition characterized by inflammation of the heart muscle 2, 3, 4, 5, 6.
- The clinical presentation of myocarditis due to influenza infection can vary from asymptomatic to fulminant myocarditis, resulting in cardiogenic shock and death 3, 4, 6.
Diagnosis of Myocarditis
- Elevated troponin levels are a hallmark of myocarditis, occurring in a significant proportion of patients with influenza infection 2.
- Electrocardiogram, echocardiogram, and cardiac magnetic resonance are valuable tools in diagnosing myocarditis 2.
- The diagnosis of myocarditis can be challenging, and a high index of suspicion is necessary, especially during influenza epidemics 4, 6.
Treatment of Myocarditis
- Angiotensin converting enzyme inhibitors, angiotensin receptor blockers, and judicious use of beta-blockers are beneficial in the management of myocarditis 2.
- Corticosteroids may be avoided during the early phase of viral replication but can be beneficial in hospitalized, critically ill patients 2.
- Statins may be useful in shortening the course of the disease and decreasing mortality 2.
- Mechanical circulatory support may be required in severe cases of fulminant myocarditis 3.
- Vaccination against influenza is an important protection strategy for both influenza infections and complications, including myocarditis 5.