Myocardial and Pericardial Disease: Difference between revisions

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 the disease presentation in particular in asymptomatic or mildy 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, a risk for SCD extends beyond mid-life. Although HCM presentation and expression is heterogeneous, and its relatively low prevalence, clinical markers as shown in Table 2 may identify patients at high risk for SCD. Patients at an unacceptably high risk of SCD are eligible for ICD implantation.

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. In at least 50% of patients with DCM, its cause cannot be determined which is referred to as idiopathic DCM. DCM is a condition which causes and presentations are highly variable. The diagnosis of idiopathic DCM should only be made after exclusion of the specific cardiomyopathies with a dilated phenotype.  

The prevalence of DCM is approximately 36 per 100 000.

The genetic background of DCM is not as clear as in HCM. Although previously thought to be sporadic, genetic transmission is now thought to account for 30-40% of cases. Multiple genes have been identified that are linked with the occurrence of DCM. Genetic disease may account in part for the primary forms of DCM, but importantly, genetic predisposure may well lead to DCM in case of exposure to precipitating factors such as (emotional) stress, excessive alcohol use or stress upon the cardiovascular system; secondary DCM.

The expression of DCM in the familial form is frequently incomplete, and hence its prevalence has been severely underestimated. Even minor abnormalities may progress into overt DCM, and accurate clinical screening of (asymptomatic) relatives is mandatory for identification of familial DCM cases.

[[File:Process of cardiac remodelling.png|thumb|right|Figure 1. Process of cardiac remodelling]]  

Probably facilitated by a genetic predisposure, DCM can be precipitated by a wide variety of factors including arterial hypertension, myocarditis, or tachyarrhythmias. A subsequent increase in wall stress combined with activation of neurohumoral pathways induces complex cellular and molecular maladaptation. Programmed cell death finally leads to a decrease in the number of functioning cardiomyocytes. This process of cardiac remodelling in itself results in systolic and/or diastolic dysfunction leading to increased wall stress, thereby creating the vicious circle of systolic dysfunction.

The failing myocardium has several distinct factors promoting apoptosis of cardiomyocytes in vitro; cathecholamins, wall stress, angiotensin II, nitric oxide and inflammatory cytokines. Hence, medical management of DCM aims at antagonizing these pathways, reducing stress signalling in and remodelling of the failing heart.

The most common first manifestation of DCM is heart failure, in which clinical symptoms do not differ from heart failure of other causes. An important feature of the physical examination is a gallop rhythm of S3 and S4, invariably present in DCM. S3 and S4 may fuse in tachycardic patients with new onset of heart failure. Special attention should focus upon excluding valvular heart disease as a cause, and the possibility of right-sided involvement should be considered.

Management of symptoms and progression of DCM, coincide with treatment options as described in the management of heart failure. Hence, also in DCM, diuretics and neurohumoral antagonists provide the basis for management of symptoms, and preventive cardio defibrillator or pacemaker implantation is indicated in selected patients with DCM. Most importantly surgical or percutaneous correction of underlying conditions facilitating progression of DCM, such as coronary artery disease, valvular heart disease or congenital abnormalities is warranted.

It is important to note that there are several causes of secondary DCM. A foursome of these are of utmost importance to recognize early on, as accurate diagnosis influences the patients treatment strategy and chance for recovery.

Alcoholic cardiomyopathy is a dose-related disorder that resembles idiopathic DCM. Cessation of alcohol use results in an improvement of the disease. Not only does alcohol have a direct toxic effect on the myocardium, excessive alcohol use also increases risk for other comorbidities that increase cardiovascular risk such as systemic hypertension.

DCM has a highly variable clinical course. Approximately half of DCM patients respond well to contemporary heart failure medication, and an minority of patients show a healing course. Conversely, a subgroup can be identified with a highly unfavourable clinical course, not responsive to heart failure medication and rapidly progressing to inotropy- or LVAD dependency. Overall, 5-year survival rates approximates 30%.