Early Diagnosis of Acute Myocarditis or Dilated Cardiomyopathy in Children Younger Than 2 Years

Diagnosis of acute myocarditis or dilated cardiomyopathy (DCM) on initial presentation is difficult in children younger than 2 years because most present with complaints suggestive of a respiratory infection. The objective of this study is to determine whether signs, symptoms, and diagnostic studies excluding those of heart failure, done routinely in the emergency department could distinguish children younger than 2 years with acute myocarditis or DCM from those with respiratory illnesses.

Sixty-four infants' charts, 32 cases and 32 controls, were reviewed from January 1, 2009, through December 31, 2020. Controls were matched to cases with respect to age, reason, and time of admission. Signs, symptoms, and blood gases were reviewed.

The median age is 6.5 (0.5-22) months in both groups. Infants presenting with signs of heart failure including murmurs ( P = 0.002), prolonged capillary refill ( P = 0.024), cool, mottled extremities ( P = 0.002), poor perfusion ( P = 0.001), or hepatomegaly ( P < 0.001) were more likely to be diagnosed with acute myocarditis or DCM when compared with the control group with respiratory disease. Infants with fever ( P = 0.017), nasal congestion ( P < 0.001), rhinorrhea ( P < 0.001), cough ( P < 0.001), and wheezing ( P < 0.001) were more likely to have a respiratory illness than acute myocarditis or DCM. The presence of a lower p co2 (30 [14-116] vs 40 [31-59] mm Hg, P < 0.001), lower bicarbonate (16.7 [6.3-23.4] vs 21.7 [16-28.4], P < 0.001), or an oxygen saturation > 95% ( P = 0.004) was observed in infants with acute myocarditis or DCM compared with those with respiratory illness. By multivariable analysis, infants with tachycardia in the absence of fever, metabolic acidosis, and an oxygen saturation > 95% were more likely to have acute myocarditis or DCM than those without this disease.

Children younger than 2 years presenting to the emergency department with tachycardia and no fever, metabolic acidosis, and a high oxygen saturation should be investigated for acute myocarditis or DCM.