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"Development of the European Network in Orphan Cardiovascular Diseases"
„Rozszerzenie Europejskiej Sieci Współpracy ds Sierocych Chorób Kardiologicznych”
Title: An overview of dilated cardiomyopathy, part I
RCD code: III-1A.1
Author: Paweł Rubiś1,2,
Affiliation:
1
Department of Cardiac and Vascular Diseases, John Paul II Hospital, Institute of Cardiology
2
Center for Rare Cardiovascular Diseases, John Paul II Hospital
Date: 18/12/2013
Introduction
According to the definition of cardiomyopathy, proposed recently by the Working
Group on Myocardial and Pericardial Diseases of the European Society of Cardiology (ESC),
it is “a myocardial disorder in which the heart muscle is structurally and functionally
abnormal, in the absence of coronary artery disease, hypertension, valvular heart disease and
congenital heart disease sufficient to cause the observed myocardial abnormality” [1].
Therefore, whenever the cardiomyopathy is suspected in an individual patient, an active and
comprehensive exclusion of those four common causes of heart damage and failure, that may
mimic the phenotype of dilated cardiomyopathy, should be performed at the beginning of
diagnostic process.
DILATED CARDIOMYOPATHY
As it was mentioned above, dilated cardiomyopathy (DCM) is diagnosed by the
presence of left ventricular (LV) dilation and left ventricular systolic dysfunction (LVSD)
after an exclusion of significant coronary artery disease (CAD), primary heart valve disease,
congenital heart disease, and arterial hypertension (HA) [1]. Although the DCM is primarily
an disorder of the LV, right ventricular (RV) dilatation and dysfunction, especially in the
presence of the secondary pulmonary hypertension (PH), is frequently observed.
Epidemiology of DCM
The most reliable data on the epidemiology of DCM comes from a relatively old study
from an Olmsted County, Minnesota conducted between 1975 to 1984, which estimated DCM
John Paul II Hospital in Kraków
Jagiellonian University, Institute of Cardiology
80 Prądnicka Str., 31-202 Kraków;
tel. +48 (12) 614 33 99; 614 34 88; fax. +48 (12) 614 34 88
e-mail: [email protected]
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prevalence at 35.5:100,00 inhabitants (1:2,700) [2]. The annual incidence of DCM is
approximately 5 and 8 per 100,000 [2]. Although DCM may occur in any age, in great
majority of cases it typically affects adolescents and young adults. Besides the fact that
ischemic heart disease is the primary cause of HF, nevertheless DCM has recently became the
most frequent diagnosis in patients referred for heart transplantation [3].
Clinical presentation of DCM
The clinical picture of DCM varies greatly. On the one hand, there are completely
asymptomatic individuals who have only abnormalities detected on electrocardiography
(ECG) and/or echocardiography. However, on the other spectrum, there are critically ill
patients with resting symptoms of dyspone and fatigue who frequently decompensate
hemodynamically and who are candidates for urgent left ventricular assist devices (LVAD) or
heart transplantation (HTX). Typically, most affected patients gradually develop progressive
heart failure (HF) symptoms, including dyspone on exertion, impaired exercise capacity,
orthopne, peripheral edemas, paroxysmal nocturnal dyspone, or thromboembolic
complications (particularly ischemic stroke). Additionally, various forms of supra-ventricular,
particularly atrial fibrillation (AF), and/or ventricular arrhythmias and/or conduction
disturbances are frequently observed. Characteristically, young patients are particularly
susceptible for severe ventricular arrhythmias (sustained ventricular tachycardia – sVT and/or
ventricular fibrillation – VF), which may lead to tragic complication of sudden cardiac death
(SCD) [4].
Natural history of DCM
The clinical course of the disease greatly varies between patients. Despite numerous
prognostic, large-scale studies and construction of robust statistical models of survival in HF,
it is still impossible to make a precise prognosis on the individual basis [5]. Except for the
cause of the DCM, which is a very strong predictor of survival, there are also powerful,
disease-independent predictors of outcome, including natriuretic peptides (particularly brain
natriuretic peptide – BNP), New York Heart Association (NYHA) functional class, LV
ejection fraction (LVEF), and peak oxygen uptake (VO2peak) during exercise [5]. Survival
studies from seventies and eighties of XX century showed very high mortality in idiopathic
DCM approaching 25% at 1 year and 50% at 5 years [4,5]. Fortunately, more recent studies
have shown better outcomes, with 5-year survival rates of approximately 20% [4].
Management of HF and DCM
The advent of modern neuro-hormonal blockade, including angiotensin converting
enzyme inhibitors (ACE-I), antagonists of beta-adrenergic receptors (beta-blockers),
angiotensin receptor blockers (ARB), or aldostreone antagonists (ARA), alongside with the
device therapy, mainly cardiac resynchronization therapy (CRT) and/or implantable
cardioverter-defibrilators (ICD) have greatly improved both the patient’s clinical status and
the long-term outcomes [4]. However, it seems apparent that both pharmaco- and devicetherapy have already reached the maximum of its effect in terms of prognosis. Therefore, only
intensive research in other fields, including causative therapy (genetic therapy), warrants
John Paul II Hospital in Kraków
Jagiellonian University, Institute of Cardiology
80 Prądnicka Str., 31-202 Kraków;
tel. +48 (12) 614 33 99; 614 34 88; fax. +48 (12) 614 34 88
e-mail: [email protected]
www.crcd.eu
further improvement of patient’s outcomes. So far it is unclear if asymptomatic individuals
with the diagnosis of DCM should also be treated with HF-guideline approved
pharmacotherapy and/or have devices implanted. There are only few studies, which
demonstrated that treating those subjects with ACE-I and/or beta-blockers may slow the
progression of LV dilatation and also may preserve LV systolic function.
Etiology of DCM
The etiology of DCM is largely heterogeneous [4]. Despite enormous progress in the
diagnosis and management of cardiovascular diseases, in many patients the causes of DCM
are unknown. In developed countries ischemic heart disease (IHD) and myocardial infarction
(MI) are the most common causes of HF, approximating 50-75% of all HF patients.
Previously, even the term of ‘ischemic cardiomyopathy’ was extensively used in the literature
but currently, this terminology is no longer recommended [4]. Nevertheless, potentially
reversible ischemia to the heart must always be sought actively, as effective therapy
(medications and revascularization) can favorably alter patient’s outcome. Obviously, the
presence of IHD and MI naturally excludes the diagnosis of cardiomyopathy at all. However,
in the widely cited study by Felker et al., even after careful medical history and non-invasive
examinations, the causative role of IHD in the development of HF, was ascertained only after
coronary angiography in up to 7 percent of patients with initially unexplained DCM [6]. Other
diagnosable causes of DCM, which always should be considering in the diagnostic process,
include: remaining types of cardiomyopathies, which may either mimic or progress to DCM,
connective tissue diseases, endocrinologic disorders, infiltrative diseases, medications and
toxins, tachycardia-induced DCM and lastly miscellaneous causes. Most of those various
diseases can be identified after careful medical history and basic laboratory and imaging
studies (ECG, echocardiography). However, some disorders, especially infiltrative diseases
may require more sophisticated examinations, such as laboratory tests, cardiac magnetic
resonance, or the histopatopatological studies.
Reference
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John Paul II Hospital in Kraków
Jagiellonian University, Institute of Cardiology
80 Prądnicka Str., 31-202 Kraków;
tel. +48 (12) 614 33 99; 614 34 88; fax. +48 (12) 614 34 88
e-mail: [email protected]
www.crcd.eu
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Paweł
Rubis
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John Paul II Hospital in Kraków
Jagiellonian University, Institute of Cardiology
80 Prądnicka Str., 31-202 Kraków;
tel. +48 (12) 614 33 99; 614 34 88; fax. +48 (12) 614 34 88
e-mail: [email protected]
www.crcd.eu