B.15 Dilated cardiomyopathy Flashcards
(Congestive cardiomyopathy)
B.15 Dilated cardiomyopathy
Definition:
Left or biventricular dilatation with structural and/or functional systolic dysfunction in the absence of coronary artery disease, abnormal loading pressures, or congenital heart disease
B.15 Dilated cardiomyopathy
Epidemiology:
Most common cardiomyopathy:
- Incidence: ∼ 6/100,000 per year.
- Sex: ♂ > ♀ (∼ 1.5:1)
- between 30 and 40 years of age, but can occur at any age.
- Ethnicity: common in African descent
B.15 Dilated cardiomyopathy
Primary causes
- Idiopathic
- Familial, due to mutations in genes that encode components for sarcomeres and desmosomes.
B.15 Dilated cardiomyopathy
** Secondary causes**
- Substance use
- Cardiotoxic medications, e.g., anthracyclines (such as doxorubicin and daunorubicin), AZT, trastuzumab
- Infection (infectious myocarditis)
- Infiltrative and autoimmune disorders
- Hemochromatosis
- Peripartum cardiomyopathy (can occur in the last trimester or up to 6 months postpartum)
- Nutritional deficiencies, e.g., thiamine (wet beriberi), selenium, carnitine
B.15 Dilated cardiomyopathy
What compensatory mechanism initially helps maintain cardiac output in dilated cardiomyopathy, and what does it lead to?
The Frank-Starling mechanism increases preload (end-diastolic volume), leading to ventricular dilation and eccentric hypertrophy.
B.15 Dilated cardiomyopathy
What is the main consequence of progressive ventricular dilation in dilated cardiomyopathy?
Decreased myocardial contractility → systolic dysfunction → reduced ejection fraction → left-sided then right-sided heart failure.
B.15 Dilated cardiomyopathy
Symptoms
- Gradual development of symptoms of congestive heart failure (Dyspnea, Ankle and abdominal swelling, Angina pectoris, Fatigue)
- Some patients may present with symptoms of arrhythmia
B.15 Dilated cardiomyopathy
Physical examination
- Systolic murmur secondary to mitral valve regurgitation or tricuspid valve regurgitation
- S3 gallop
- Displacement of the apex beat
- Jugular venous distention
- Bilateral rales
- Peripheral edema
- Ascites
B.15 Dilated cardiomyopathy
What is the first-line test to confirm dilated cardiomyopathy?
Echocardiography – it shows ventricular dilation and reduced LVEF.
B.15 Dilated cardiomyopathy
What findings are typical on echocardiography in DCM?
Ischemic cardiomyopathy – evaluate for CAD, especially in patients >35.
B.15 Dilated cardiomyopathy
What tests are used to screen first-degree relatives of patients with familial DCM?
Physical exam, ECG, and echocardiography.
B.15 Dilated cardiomyopathy
Treatment
- Treat the underlying cause of DCM: e.g., manage endocrine abnormalities, encourage abstinence from alcohol.
- Avoid cardiotoxic agents, if possible.
- Treat congestive heart failure, if present.
- In severe or refractory disease, consider:
AICD with or without cardiac resynchronization therapy
Left ventricular assist devices
Heart transplantation
B.15 Dilated cardiomyopathy
When is pregnancy not recommended in patients with DCM?
If LVEF < 30% and/or NYHA class III–IV symptoms.
B.15 Dilated cardiomyopathy
What should be done before pregnancy in a patient with DCM?
Stop ACE inhibitors/ARBs, assess cardiac function, consider exercise stress testing, and offer genetic counseling if familial.
B.15 Dilated cardiomyopathy
What are the main complications of DCM?
Heart failure, arrhythmias, thromboembolism, and sudden cardiac death.
B.15 Dilated cardiomyopathy
What device is used as a bridge to transplant or for ineligible patients with end-stage DCM?
A left ventricular assist device (LVAD).
