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- Clinical diagnostic tests
- Radiology (diagnostics)
- Infectious diseases
- Tropical medicine (infectious disease)
A 30-year-old man with a history of non-Hodgkin’s lymphoma presented with oppressive chest pain radiating to the left arm. ECG revealed sinus rhythm (60 bpm), and non-specific T wave changes in leads DI and DII, without ST-segment elevation; troponin I level was elevated: 6.39 ng/mL (normal value <0.120 ng/mL). Echocardiography showed left ventricle ejection fraction of 58%, no systolic or diastolic disturbances, valve abnormalities or other lesions. He was referred to our institution with a suspicion of a non-ST segment elevation myocardial infarction. Due to this unusual diagnosis at his age, other causes of chest pain were ruled out. In a new interview, the patient indicated that he had had fever and diffuse myalgias after a trip to an endemic dengue region 2 weeks before. Thus, dengue-specific antibodies were ordered, which disclosed reactive IgM, negative IgG and negative non-structural protein 1.
Gadolinium cardiac MRI (CMRI) showed normal cardiac chamber size, preserved right ventricular ejection fraction and left ventricular systolic function in the lower limit (52%), with diffuse hypokinesis. Pericardial effusion and changes in pericardial thickness were absent. There were findings compatible with myocarditis in the tissue characterisation and gadolinium enhancement sequences (figures 1, 2A and B). The evolution of the patient was uneventful, and he recovered completely.
Dengue fever is caused by any of the four serotypes of the dengue virus transmitted by the mosquito species Aedes aegypti and Aedes albopictus. It is a rapidly spreading mosquito-borne viral disease, endemic in some countries with a high prevalence rate. WHO (2009) classifies dengue into two major categories: dengue (with or without warning signs) and severe dengue. Significant organ involvement (liver, central nervous system, heart or other organs) is present in severe dengue cases.
Cardiac manifestations of dengue include pericardial effusions, myocarditis, atrioventricular block, ectopic ventricular beats and atrial fibrillation.1 The prevalence of myocarditis in hospitalised dengue patients is 11.28%. It is higher in patients with non-severe dengue with warning signs and severe dengue (46.6%), than in patients with non-severe dengue without warning signs (9.72%).2 In a patient who died of myocarditis, Salgado et al found a direct dengue virus invasion of cardiomyocytes, myocardial interstitial cells and endothelial cells, along with increased proinflammatory markers, and abnormal calcium homoeostasis.3 Usually, dengue myocarditis is resolved with supportive care.4–6 Some deaths have been reported, mostly when a prompt diagnosis was not made.3 5
CMRI is vital for an earlier myocarditis diagnosis in dengue fever infection, applying diagnostic criteria that target tissue inflammation—Lake Louise Consensus Criteria. These criteria are compatible with myocardial inflammation—with a sensitivity of 76% and specificity of 96%—if two out of three are met: (1) Regional or global myocardial signal intensity increase in T2-weighted oedema images; (2) increased global myocardial early gadolinium enhancement ratio between myocardium and skeletal muscle in gadolinium-enhanced T1-weighted images and (3) at least one focal lesion with non-ischaemic regional distribution in inversion recovery-prepared gadolinium-enhanced T1-weighted images.7
Young patients with chest pain should prompt the physician to rule out other diagnoses besides myocardial ischaemic infarction.
Myocarditis caused by dengue is infrequent but can be life-threating in some cases.
Lake Louise Consensus Criteria should be assessed in MRI to establish the diagnosis of myocarditis.
We thank Dr Luis V Syro for the revision and corrections made to the article.
Contributors Category 1: Conception and design of study: JFB, CDA, DS, JFL. Recollection of data: JFL, CDA, DS, JFL. Analysis and/or interpretation of data: JFB, CDA, DS and JFL. Category 2: Drafting the manuscript: JFB, CDA, DS and JFL. Revising the manuscript critically for important intellectual content: JFB, CDA, DS and JFL. Category 3: Approval of the version of the manuscript to be published: JFB, CDA, DS and JFL.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient consent for publication Obtained.
Provenance and peer review Not commissioned; externally peer reviewed.