Viral myocarditis (VMC) is one of the common heart diseases to endanger human health in different age groups, especially children. The VMC incidence is tending to increase further in the twenty-first century [5-7].
In the present study a total of 19 clinically suspected myocarditis patients with clinical evidence of microbial infections in recent weeks. The main clinical manifestations of the patients were fatigue, respiratory distress, chest pain, precordial discomfort, palpitations, periorbital edema and abdominal discomfort. Moreover, hepatomegaly, abdominal distention and ascites, subcostal and intercostal retraction, hypotension, low heart sound blunt and all kinds of arrhythmia, including premature ventricular, atrial contraction and bradycardia can be reported on physical examination.
The results of using multiplex Real-time PCR for differential detection of viral genomes in blood or pericardial fluid samples indicated that 21.05% patients with myocarditis (MCI) were found to be virus positive. In the study of Jeserich et al.  in Germany using nested RT-PCR, 38% of peripheral leukocytes and/or plasma samples of MCI patients were virus positive. In another study, the viral nucleic acids were detected in ventricular and peripheral serum, and Endomyocardial biopsy (EMB) samples of 14%, 20%, and 46% patients with MCI, respectively . In general, the incidence of VMC varies in different studies appear to depend on the geographical distribution, various virus identification methods and sample sites.
Recently, studies indicated that the viral spectrum of VMC has greatly changed with the rising VMC incidence rate and continuous improvement in virus detection methods [2, 6]. The spectrum of viruses that were detected in our study (HHV-6/7, Parvovirus B-19, EBV, VZV and Adenoviruses) was comparable with the results of previously published studies. In Pawlak and colleague study , PB19V, human enteroviruses (HEV), human adenovirus (HAdV), and HHV-6 were detected in samples of patients with myocarditis. Another study demonstrated that the most prevalent virus infection in MCI patients was EBV infection followed by HHV-7. In addition, one patient was found to be PVB19 positive and HHV-6 variant B genome was detected in another patient . Griffin found the viral spectrum of VMC in myocardial specimens was mostly HAdV, followed by HEV, as well as CMV and HSV . Finally, VMC caused by multiple viruses is also more common than before [6, 12]. The results of our study showed that among the patients with VMC, a co-infection of HHV-6/7 and Parvovirus B-19 was found in the one patient. Jeserich et al  also reported two VMC patients with confections of EBV and HHV-7.
At present, the ECG and Holter monitoring are still one of the important indicators of VMC [13, 14]. In our study, ECG findings such as sinus tachycardia, ST-T changes, premature ventricular contraction (PVC) and complete heart block (CHB) were reported patient with VMC. Furthermore, 24 hours Holter-ECG monitoring in one of the patients revealed one episode of ventricular tachycardia running. Similar to our study, the results of a previous study showed that ECG findings such as new atrial or ventricular premature beats were found in 62% of VMC patients, new right or left bundle block in two virus positive patients, and new atrial fibrillation and ST-T changes in three patients . Niu and et al.  also revealed that ECG examination and 24 hours dynamic ECG was positive in 88.71% and 92.31% children with viral myocarditis, respectively.
Finally, the results of the present study showed that the AST abnormal increase was found in three VMC patients and the LDH abnormality in the one patient. While, there was no abnormal increase in CK-MB and CK enzymes in the patients. In a previous study, the abnormal rate of myocardial enzymes was reported in 96.77% of VMC patients that CK-MB abnormal increase was more common, followed by LDH anomaly . Although elevated cardiac enzymes can be present in myocarditis, but studies have shown that the increase in myocardial enzymes is non-specific and these enzymes can be elevated due to other conditions [6, 15]. Moreover, cardiac troponins are well established as the best indicators of myocardial injury [6, 16]. In our study, the troponin assay was negative in all VMC patients. In Smith and colleague study , cardiac troponin I values were elevated in 18 (34%) of 53 patients with myocarditis. In another study, an elevated cardiac troponin level was reported in all patients with myocarditis . It is noteworthy that the cardiac troponin levels depend on numerous factors such as time of measurement and severity of myocardial injury. In addition, cardiac troponin in serum is not stable and can be affected by endogenous material.