During this season of the ever-present viral respiratory illness, we must be on the lookout for the potentially-deadly -entity of myocarditis. A recent study suggests some clues to when the diagnosis should more strongly be considered in patients presenting with viral respiratory symptoms.
1. Most cases of myocarditis were not initially recognized by primary care MDs or emergency health care providers. 84% of patients needed more than one visit within 2 weeks before the diagnosis was made. This highlights the difficulty in Dx and frequent misdiagnosis rate. 2. The most common presenting symptom was dyspnea (69%) and most common sign was tachypnea (60%). 3. Although resting tachycardia is often taught as a common finding, 66% of patients had a normal HR. 4. The most helpful findings in terms of helping distinguish myocarditis from benign common viral URIs was hepatomegaly (present in 50%) and cardiomegaly (present in 60%). 5. An abnormal ECG was present in 100% of cases. The most common abnormalities were tachycardia, ventricular hypertrophy, and ST or T wave changes. 6. 54% of patients had elevated troponin levels.
So what's the bottom line? 1. If your patient has tachypnea or dyspnea, strongly consider getting a CXR. In that case, look carefully for cardiomegaly. 2. Always assess for and document the presence or absence of hepatomegaly. 3. A completely normal ECG is strong evidence against myocarditis.
[Durani Y, Egan M, Baffa J, et al. Pediatric myocarditis: presenting clinical characteristics. Am J Emerg Med 2009;27:942-947.]
