Myocardial Disease: Difference between revisions

__TOC__

Two-dimensional echocardiography is the easiest diagnostic modality for detection of HCM, (Table 2) but cardiac magnetic resonance imaging (CMR) may be used when echocardiography is inconclusive, acoustic windows are insufficient, or when more detailed anatomic information is needed for clinical decision making. Echocardiographic characteristics include thickening of the left ventricular wall without cavity dilatation, and a normal or hyperdynamic left ventricle. Left ventricular outflow tract obstruction is not mandatory for the diagnosis of HCM. Moreover, as mentioned previously, although the diagnosis of HCM is based on a cut-off value for maximal wall thickness of 15 mm in the overall population, multiple HCM-linked mutations are associated with only minor LVH, but represent a high risk of sudden cardiac death.  

|-

!Table 2. Echocardiographic diagnostic criteria for HCM in first-degree relatives of index cases with HCM :

Electrocardiographic signs of HCM are typical as the increase in myocardial tissue increases the size of the QRS complexes. Therefore, a typical ECG characteristic of HCM is that it meets voltage criteria for LVH, and shows changes in repolarization (Table 3).

|-

!Table 3. Electrocardiographic diagnostic criteria for HCM in first-degree relatives of index cases with HCM :

In general, symptoms of HCM increase with age. Mortality rates have been reported to account between 2 and 3% per year. Most importantly, patients with HCM may be at high risk of sudden cardiac death, which may even be its initial presentation, in particular in asymptomatic or mildly symptomatic young patients. HCM is the most common cause of SCD in young people, including athletes. The pathophysiological basis for this predilection is unclarified, and although SCD is most frequent in young people less than 30 to 35 years old, an increased risk for SCD extends thereafter. Although HCM presentation and clinical manifestation is heterogeneous, and it has a relatively low prevalence, clinical markers as shown in Table 4 may identify patients at high risk for SCD. Patients at high risk of SCD are eligible candidates for ICD implantation.

|-

!Table 4. Risk factors for SCD

*Fibrosis on CMR

|}

===Dilated cardiomyopathy===

Dilated cardiomyopathy (DCM) is a primary myocardial disease characterized by ventricular dilatation (one or both ventricles) and impaired myocardial contractility. The impairment of myocardial function cannot be explained by abnormal loading conditions alone, such as valve disease or systemic hypertension. The prevalence of DCM is approximately 36 per 100 000; in at least 50% of patients with DCM, its cause cannot be determined which is referred to as idiopathic DCM. DCM is a condition of which causes and presentations are highly heterogeneous. The diagnosis of idiopathic DCM should only be made after exclusion of the specific cardiomyopathies with a dilated phenotype.  

An important differentiation is that between RCM and constrictive pericarditis. Constrictive pericarditis is similarly characterized by impaired ventricular filling with preserved systolic function, but may be adequately treated by pericardiectomy, which makes this distinction of major clinical importance.

|-

!Table 5 - Classification of Restrictive Cardiomyopathy  

===Arrythmic cardiomyopathy: Arrhythmogenic Right Ventricular Cardiomyopathy===

ARVC is a progressive disease, and its incidence is estimated to be 1:3.000-1:10.000. The disease usually manifests at adolescence. Although the diagnosis is more often confirmed in athletes, physical activity is not thought to have a causal relationship with the disease. ARVC can occur in families; more than 9 different chromosomal defects have been described, most often with autosomal dominant inheritance. One unique form of ARVC, called Naxos disease (after the Greek island where it was first diagnosed), has an autosomal recessive pattern of inheritance.  

====Diagnosis====

ARVC is a difficult diagnosis to make. Therefore, the European Society of Cardiology has created a list of diagnostic criteria for the diagnosis of ARVC, which were updated in 2009 (Table 6). An [http://www.arvc.ca/pdg/public.php?rep=arvc_cri online calculator] can help in assessing the risk in an individual patient.  

|-

! Table 6. The Revised Task Force Criteria for ARVD / ARVC Revised Task Force Criteria

|'''Minor'''

|-

|-

|Inverted T waves in leads V1, V₂, V₃, and V₄ in individuals >14 years of age in the presence of complete right bundle-branch block  

† A pathogenic mutation is a DNA alteration associated with ARVC/D that alters or is expected to alter the encoded protein, is unobserved or rare in a large non–ARVC/D control population, and either alters or is predicted to alter the structure or function of the protein or has demonstrated linkage to the disease phenotype in a conclusive pedigree. E.g.: in TMEM43, DSP, PKP2, DSG2, DSC2, JUP.  

|}

====Treatment====

*ICD implantation is recommended for the prevention of sudden cardiac death in patients with ARVC with documented sustained VT or VF who are receiving chronic optimal medical therapy.  

*ICD implantation can be considered for the prevention of sudden cardiac death in patients with ARVC with extensive disease, including those with left ventricular involvement, 1 or more affected family member with SCD, or undiagnosed syncope when ventricular tachycardia or ventricular Fibrillation has not been excluded as the cause of syncope, who are receiving chronic optimal medical therapy, and who have reasonable expectation of survival with a good functional status for more than 1 year.  

===Unclassified Cardiomyopathy: Left ventricular non-compaction===