Myocardial and Pericardial Disease: Difference between revisions

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 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 ===
+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.
+==== Epidemiology ====
+The prevalence of DCM is approximately 36 per 100 000.
+==== Genetics ====
+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.
+==== Pathophysiology ====
+[[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.
+==== Clinical diagnosis ====
+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.
+Diagnostic testing in DCM should focus on identification of reversible causes, and includes plasma biomarkers, noninvasive imaging, electrocardiography and exercise testing.
+Echocardiography is an important diagnostic modality in DCM, as it can be used to assess both the size and shape of the LV, but also to determine LV function by assessing the LV ejection fraction (EF). Furthermore, valvular heart disease or pericardial abnormalities can be excluded.  CMR evaluation may contribute to identification of specific cardiomyopathic conditions, especially when echocardiographic images are suboptimal. Cardiopulmonary exercise testing is a measure of the cardiac response to exertion, and is an established risk factor in DCM patients. Furthermore, the combination of anaerobic threshold and ventilatory efficiency is a reliable predictor for 6-month mortality. Dilatation of the ventricular cavity results in myocyte stretch. In response, B-type natriuretic peptide is released, which is a neurohorme that can be used to evaluate progression of DCM and to guide medical treatment. High plasma concentrations (twice the ULN) are furthermore associated with increased long term mortality.
+Electrocardiography does not provide an accurate diagnostic mean in DCM, but can identify several features associated with impaired prognosis, or identify contributing factors to DCM. Where sinus tachycardia is frequently present, non-specific ST-segment or T-wave changes, as well ass changes in P-wave morphology may well be present.
+AF is an important feature associated with high mortality; its control may contribute to optimalise cardiac output. Furthermore, the presence of AF may indicate tachycardia-induced cardiomyopathy. 24-hour Holter monitoring can reveal a decreased heart rate variability or complex ventricular arrhythmias which are associated with a high risk for mortality. Finally, prolonged QTc intervals are associated with high mortality.
+==== Management of DCM ====
+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.
+==== Specific dilated cardiomyopathies ====
+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.
+''Tako-tsubo (Stress)''
+Tako-tsubo (octopus pot) cardiomyopathy is an acute cardiomyopathy precipitated by exposure to high doses of cathecholamines. It is most common in middle-aged women, and is usually completely reversible wit supportive care. Diagnostic features include electrocardiographic signs of myocardial infarction, without angiographic evidence of coronary artery disease. A distinctive feature is the presence of apical and midventricular systolic dysfunction in which the base of the heart is relatively spares, which is referred to as apical ballooning. Endomyocardial biopsy may mimic myocardial infarction, and demonstrates contraction band necrosis, but may be useful to exclude myocarditis.
+''Peripartum cardiomyopathy''
+Peripartum cardiomyopathy is defined as ‘a cardiomyopathy manifesting between the last month of pregnancy and 6 months post partum’. Most probably, inflammatory factors play a prominent role in its aetiology, but it remains to be fully elucidated. The initial period may feature severe hemodynamic compromise, but if patients survive this period long-term prognosis is excellent, although these women are at higher risk of reccurrence with a subsequent pregnancy.
+''Peripartum cardiomyopathy''
+Peripartum cardiomyopathy is defined as ‘a cardiomyopathy manifesting between the last month of pregnancy and 6 months post partum’. Most probably, inflammatory factors play a prominent role in its aetiology, but it remains to be fully elucidated. The initial period may feature severe hemodynamic compromise, but if patients survive this period long-term prognosis is excellent, although these women are at higher risk of reccurrence with a subsequent pregnancy.
+''Alcoholic cardiomyopathy''
+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.
+==== Prognosis and outcome ====
+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%.