Download Dilated Cardiomyopathy Allen Repp, M.D. November 5, 2002

DILATED CARDIOMYOPATHY
Allen Repp, M.D.
November 5, 2002
Introduction
 Cardiomyopathy refers to disease of the myocardium associated with cardiac dysfunction
 5 types of cardiomyopathies identified by WHO, each of which may have multiple etiologies:
dilated, hypertrophic, restrictive, arrhythmogenic right ventricular, and unclassified
 Dilated cardiomyopathy (DCM) is characterized by ventricular dilation (LV end diastolic dimension
> 60 mm) and impaired contraction of one or both ventricles (LV EF generally < 30%)
 Idiopathic DCM is the most common primary cardiomyopathy, and the most common
indication for cardiac transplantation in the US
 DCM is the 2nd most common cause of heart failure (after ischemic heart disease)
Clinical Presentation
 Majority of cases occur in ages 20-60, but can occur in children or elderly
 Presentation may be acute, sub-acute, or chronic
 Symptoms may reflect numerous complications of DCM
 Congestive heart failure – Progressive dyspnea on exertion, impaired exercise capacity,
PND, orthopnea, dependent edema, ascites, early satiety
 Arrhythmia – Syncope, presyncope, palpitations, sudden death
 Thromboembolic events – Cerebrovascular accident, pulmonary embolism
 Incidental detection of asymptomatic cardiomegaly
Etiologies of DCM
 Idiopathic
 Cause of DCM will remain unexplained in approximately 50% after thorough evaluation
 Ischemic
 Accounts for up to 7% of cases of initially unexplained dilated cardiomyopathy
 Infectious Myocarditis
 Viral: coxsackievirus, echoviruses, adenoviruses, HIV, CMV, hepatitis, varicella, EBV
 Bacterial: streptococci (rheumatic fever), typhoid fever, diphtheria, brucellosis, psitticosis
 Spirochetal: Lyme disease (usually presents with conduction disturbances, but rarely with
myocarditis and heart failure)
 Rickettsial disease
 Parasitic: Chagas disease, aka trypanosomiasis (acute tissue invasive phase or chronic
phase), toxoplasmosis, shistosomiasis, trichinosis
 Fungal / Mycobacterial: histoplasmosis, cryptococcus
 Non-Infectious Myocarditis
 Rejection of allograft in cardiac transplant patient – the paradigm for lymphocyte-mediated
myocarditis
 Connective tissue diseases: SLE, polymyositis
 Peripartum cardiomyopathy
 Hypersensitivity reactions
 Sarcoidosis – 10% of patients with sarcoidosis experience clinical cardiac involvement
 Giant cell myocarditis – rare, frequently fatal inflammation of myocardium with prominent
ventricular tachyarrhythmias, chest pain, and hemodynamic compromise
 Autoimmune myocarditis – possibly related to anti-1 adrenoreceptor antibodies
 Celiac sprue
 Toxins
 EtOH – alcohol and metabolite acetaldehyde are direct cardiotoxins that can induce acute,
reversible myocardial dysfunction or chronic, partially irreversible myocardial depression
 Chemotherapeutic agents – most notably, doxorubicin, but also cyclophosphamide and
trastuzumab (anti-c-erbB-2 monoclonal antibody used in treatment of some breast cancers)
 Other medications – zidovudine, didanosine, zalcitabine, phenothiazines
 Heavy metals and occupational exposures – mercury, lead, beryllium, carbon monoxide
 Illicit drug use: amphetamines and cocaine may produce state of catecholaminergic excess
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 Radiation
Metabolic
 Nutritional deficiencies – thiamine, selenium, carnitine
 Electrolyte abnormalities – hypocalcemia, hypophosphatemia, hypomagnesemia
 Renal failure – uremia
 Endocrinopathies – hypothyroidism or hyperthyroidism, growth hormone excess or
deficiency, diabetes mellitus, pheochromocytoma, Cushing’s disease
Familial / Inherited
 Neuromuscular diseases – Duchenne, Becker’s, and facioscapulohumeral dystrophy
 Mitochondrial myopathies – e.g. Kearns-Sayre syndrome
 Deposition diseases – hemochromatosis, hereditary sideroblastic anemias
Other
 Tachycardia mediated cardiomyopathy – observed in patients with chronic supraventricular
tachycardias, with severity of LV dysfunction correlating with rate of arrhythmia
 Obstructive sleep apnea
Evaluation
 History
 Elicit onset of symptoms – rapid development over days to weeks suggests post-viral or giant
cell myocarditis
 Characterize extent of exercise intolerance / dyspnea, as NYHA class has prognostic
significance
 Document history of EtOH use, illicit drug use, occupational exposure history, travel history
(yes, doctor, I lived in rural South America for 5 years), dietary history (especially
consumption of raw meat)
 Family history
 Examination – elevated jugular venous pressure, abnormal hepatojugular reflux, hepatic
distention, ascites, peripheral edema, rales, laterally displaced LV impulse, S3 or S4 gallop, RV
impulse, murmurs of MR and/or TR
 Routine initial laboratory evaluation
 ECG, CXR, ECHO;
 CBC with differential (evaluate for eosinophilia)
 Serum chemistries, BUN / Cr, LFTs, CK, TSH
 Secondary laboratory evaluation
 Infectious workup – coxsackie, echovirus, influenza, HIV, Lyme, toxoplasma, trypanosoma
 Rheumatologic screening
 MRI
 Coronary arteriography
 Endomyocardial biopsy – only definite indications are monitoring transplant rejection and
anthracycline toxicity
Treatment
 Abstention from EtOH
 Avoidance of vigorous exercise x 3-6 months (if ongoing, active process suspected)
 Immunization against influenza and pneumococcus
 Medical therapy for CHF: ACEi, -blockers, diuretics, +/- digitalis glycosides
 Consider anticoagulation for patients with hx of thromboembolism, a. fib, or LV thrombus
 Immunosuppressive therapy with prednisone, azathioprine, or cylcosporine has been advocated
by some for biopsy proven myocarditis, but there is no evidence for its efficacy at present
 Coronary revascularization if evidence of ischemic heart disease with myocardial viability
 Consideration of implantable defibrillator for patients with hx of sudden death, sustained VT, or
inducible VT
 Cardiac transplantation
Prognosis
 Recent onset DCM associated with 50% chance of “substantial” recovery
 Worse prognosis with lower functional status at presentation (1 year mortality < 10% for patients
in class I CHF, but 50% for patients in class IV CHF)
 Outcome better in patients with peripartum cardiomyopathy, but substantially worse in patients
with infiltrative disease, HIV, or doxorubicin toxicity
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