Deadly Complication behind Dengue Fever: Myocarditis

In the past, a mosquito bite used to be nothing more just another annoying itch. With dengue fever cases on an all-time high in 2020, getting a mosquito bite has now become an alarming call; especially if there are also symptoms such as high fever, rashes, muscle and joint pains.

Among these patients, a small proportion of them can experience various complications resulting in deaths. Myocarditis is one of them.

Proven to Worsen Condition of Dengue Fever Patients

Myocarditis, the acute inflammation of myocardium, is a common complication of dengue infection. During the worst dengue outbreak in China in 2014, 201 out of 1782 infected patients who were part of a research study were found to have myocarditis. It is also discovered that the incidence of myocarditis increased with the severity of dengue infection.

Another fatal case involving a 41-year-old Chinese national brought up in a 2013 study showed that the patient experienced a complicated dengue viral infection with acute myocarditis.

Dengue fever-induced myocarditis is a common cause of dengue deaths. It can be fatal when diagnosed and treated late.

Diagnosing Myocarditis

Dengue fever patients with myocarditis would usually experience symptoms such as chest pain, breathlessness and exhibit ‘rubbing’ sounds in the chest and heart.

The condition can be diagnosed via echocardiogram, cardiac enzyme test or electrocardiogram (ECG). Based on the patient’s medical history, specialists can also deduce if the patient is likely to be suffering from myocarditis.

In the same study conducted in 2014, it was found that most dengue patients with myocarditis were ECG-positive. This suggests that suspect patients should undergo an ECG examination first due to its high sensitivity.

For patients with severe dengue haemorrhagic fever, the critical phase of potential myocardial injury and organ failure tend to develop when fever subsides. This occurs in day four to seven of dengue fever. Cardiac examination and ECG are therefore crucial during this period for patients demonstrating cardiac symptoms as early detection and intervention can save lives.

Treatment and Prevention

Treatment for dengue fever is largely supportive. However, in the case where myocarditis is present, additional medication could be used to reduce the risk of heart failure or arrhythmia.

In more severe cases, doctors may improve the heart pumping function better with intravenous (IV) medications and inotropic BP supporting medications. Additional medications for heart failure and anti-inflammatory medications can also be used to save the heart and patient’s life, when administered early.  

There is no known prevention measures for myocarditis but it is advisable to avoid any forms of viral infection because when an infection takes place, our body produces cells – which in turn release chemicals such as cytokines – to fight against it. When these chemicals enter the heart, it can inflame the heart muscle hence causing myocarditis.

Those aged 12 to 45 with a history of dengue fever can get vaccinated against dengue fever with Dengvaxia, a dengue vaccine approved by the World Health Organization and Ministry of Health. This helps to minimise the risks of complications like myocarditis during subsequent dengue exposures, as repeated dengue infection posts the highest risk of severe complications.

Article contributed by Dr Eric Chong, Senior Cardiology Consultant, ESC Cardiovascular and Medicine Clinic at Farrer Park Hospital.

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