A 43-year-old man was admitted to the Clinica de las Americas (CDLA) in Santa Cruz de la Sierra, Bolivia, presenting with moderate-intensity, continuous crushing chest pain radiating to the lower jaw and the left shoulder. The pain had started two days prior and had progressively increased in intensity.
Five days prior to his hospitalization, the patient had presented to the emergency department for fever, headache, retro-orbital pain, general body aches, and joint pain. Due to the high degree of suspicion and multiple cases of dengue in the community, a dengue test (ELISA IgM) was performed, yielding a positive result, which was subsequently confirmed through reverse transcriptase polymerase chain reaction (RT-PCR). The patient was hemodynamically stable with no signs of heart failure, exhibiting no murmurs or rubs on auscultation, and a chest-radiography performed at that time showed normal results.
The patient's electrocardiogram (EKG) revealed sinus rhythm with a heart rate of 95 beats per minute. Additionally, an ST segment elevation of 2 mm was observed in leads II, III, aVF, and V4 to V6 (Figure 1). This was interpreted as acute coronary syndrome with ST-segment elevation, so blood tests (including cardiac biomarkers) were requested and the myocardial infarction protocol (primary angioplasty) was activated. However, a coronary angiography revealed no significant lesions.
Simultaneously, a transthoracic echocardiogram was performed, revealing normal systolic function in both ventricles. The left ventricular ejection fraction (LVEF), assessed using Simpson's method, was 66%, and the diastolic function was preserved. Longitudinal deformation was -19.8% with a minor decrease in the deformation affecting the basal and medial inferoseptal segment. Finally, the parietal pericardium was found enlarged and diffusely hyperechogenic, suggesting an inflammatory process at that level (Figure 2).
Complete blood count and basic metabolic panel lab results all yielded normal results, with hemoglobin of 12.6 g/dl, hematocrit of 39.2%, leukocyte count of 8700 cells/mul with normal differential and a platelet count of 263,000/mul. Creatinine, sodium and potassium levels were 0.7 mg/dl, 142 mEq/L, and 4.6 mEq/L, respectively. Cardiac markers were slightly elevated, with a NT-proB-type Natriuretic Peptide (NT-proBNP) level of 678 pg/mL (normal value <125 pg/ml), a troponin T level of 154 ng/L (normal value <14), but with a normal creatine phosphokinase (CPK) value of 88 U/L (normal value <308 U/L).
Cardiac magnetic resonance imaging (MRI) with gadolinium revealed normal-sized cardiac chambers, preserved right ventricular function, and a LVEF of 52% (lower than the normal range) in a context of mild hypokinesia of the inferior wall of the left ventricle (basal and medial segments) (Figure 3).
The presence of myocardial edema was also observed in the same inferior wall with inferoseptal extension (Figure 4). Late enhancement sequences revealed gadolinium uptake in the basal, medial, and inferior basal inferoseptal segments of the left ventricle, and the pericardium in its basal region (Figure 5). All of these findings are consistent with acute myocarditis.
The differential diagnosis also included a number of pathologies characterized by chest pain, such as acute coronary syndromes, aortic dissection, pulmonary embolism, pneumonia, pneumonitis, tuberculosis, viral myocarditis, musculoskeletal disorders, gastric ulcer, gastroesophageal reflux disease, pneumothorax, herpes zoster, depression, and panic disorder.
Considering the exclusion of acute myocardial infarction through normal coronary angiography, the clinical findings, elevated cardiac biomarkers, positive specific serology, suggestive cardiac images, and the epidemiological context, a dengue myocarditis diagnosis was suggested.
The patient was treated with nonsteroidal anti-inflammatory drugs (NSAIDs), acetylsalicylic acid, and colchicine, resulting in clinical improvement of pain and reduction in cardiac biomarkers levels. During the first 24 hours of admission, the patient had persistent hiccups, which were effectively managed with intravenous metoclopramide. Discharge was effective on the third day of admission with prescriptions for acetylsalicylic acid (750 mg every eight hours for one week) and colchicine (0.5 mg daily for two weeks).