**Part 1**

**Myocarditis from Clinical Perspective** 

**1** 

*Qatar* 

**Clinical Presentation** 

*Cardiovascular Surgery Department* 

*Hamad Medical Corporation, Cardiology and* 

Myocarditis is a clinical syndrome characterized by inflammation of myocardium. It can be produced by a myriad of etiologies including infectious, autoimmune, myocardial toxins, hypersensitivity reactions and physical agents. Virtually any infectious agent can produce myocardial inflammation and injury. Human myocarditis is most frequently caused by viral infection. Ongoing viral infection, myocardial destruction, and adverse remodeling can lead to persistent ventricular dysfunction and dilated cardiomyopathy. The modern molecular techniques have facilitated new insights into inflammatory autoimmune processes that affect the myocardium and ultimately result in acute or chronic dilated cardiomyopathy. The clinical manifestations are highly variable, ranging from asymptomatic electrocardiographic or echocardiographic abnormalities to acute myocardial infarction-like syndrome, overt congestive heart failure, fulminant condition with new atrial or ventricular arrhythmias or profound cardiogenic shock and death. Myocarditis is occasionally the unrecognized culprit in cases of sudden cardiac death. Autopsy series have reported much higher rates of myocarditis than expected with overt clinical manifestation from different etiological agents. The prospective postmortem data have implicated myocarditis in sudden cardiac death of young adults at rates of 8.6 percent to 12 percent (Doolan et al., 2004; Fabre & Sheppard, 2005). Furthermore, it has been identified as a cause of dilated cardiomyopathy

The clinical history in patients presented with myocarditis remains essential to envelop a wide variety of etiologies in the clinical scenarios, many of which are infectious (Brodison & Swann, 1998). In the past 10 years, however, viruses, including adenovirus, parvovirus B19, hepatitis C, and herpes virus 6, have emerged as significant pathogens (Mahrholdt et al., 2006). The geographical distribution can be of relevance for some forms of myocarditis. In selected countries, Chagas disease, Lyme myocarditis, acute rheumatic fever and disorders associated with advanced human immune deficiency virus infection are significant causes. Other important infrequent clinicopathologic variants in the etiological spectrum are systemic disorders like giant cell myocarditis, cardiac sarcoidosis and eosinophilic myocarditis. Additionally, drugs, vaccinations, toxins, physical agents like radiation, heat stroke and hypothermia can be the key point for some rare clinical diagnoses. The physical examination in patients with myocarditis might be normal, but more severe cases frequently evident for significant physical findings. Although histological findings remains the gold standard for establishing the diagnosis of myocarditis, low risk patients are often given a

in 9 percent of cases in a large prospective series (Felker et al., 1999).

**1. Introduction** 

Rafid Fayadh Al-Aqeedi
