Dilated Cardiomyopathy

Other Names

• Congestive Cardiomyopathy
• Dilated Cardiomyopathy (DCM)
• Congestive Cardiomyopathy
• Idiopathic Dilated Cardiomyopathy
• Nonischemic Dilated Cardiomyopathy
• Familial Dilated Cardiomyopathy
• Primary Dilated Cardiomyopathy
• Secondary Dilated Cardiomyopathy
• Dilated Cardiomyopathic Heart Disease
• Dilated Myocardiopathy
• Dilated Heart Muscle Disease

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Background

• This page discussed Dilated Cardiomyopathy (DCM)

History

• Needs to be updated

Epidemiology

• Most common cardiomyopathy 6/100,000 per year
• Can occur at any age but most common in 30-40s
• More common in people of African decent
• 1.5:1 ration male to female

Introduction

General

• Dilated cardiomyopathy (DCM) is characterized by enlargement of one/both ventricles with reduced systolic function
• Common causes include genetic mutations, viral myocarditis, alcohol misuse, chemotherapy exposure, idiopathic
• Clinical presentation includes heart failure symptoms, exercise intolerance, arrhythmias, thromboembolism, sudden cardiac death
• Diagnosis is made with echocardiography demonstrating ventricular dilation and decreased ejection fraction

Definition

• Left or biventricular dilation with impaired systolic function that is not secondary to CAD, abnormal loading pressures (i.e., HTN, or underlying valvular disease) or congenital heart disease. Is the most common type of cardiomyopathy.

Etiology

• Genetics is the most common cause (~25-45% of cases)
  • Mutations in genes that encode sarcomeres, and desmosomes, like:
    • TTN gene: encodes intrasarcomeric protein titin
    • MYH7 gene: encodes beta-myosin heavy chains
  • LMNA gene: encodes protein structure w/in nuclear membranes
• Idiopathic
• Infectious/inflammatory
  • Viral myocarditis is most common infectious cause
    • Coxsackie B Virus
    • HIV
    • Adenovirus
    • Influenza A & B
    • Herpes
  • Bacterial is far less common
• Infiltrative, Autoimmune and Neuromuscular
  • Systemic Lupus Erythematosus
  • Sarcoidosis
  • Vasculitis
  • Myotonic dystrophy
  • Duchene muscular dystrophy
  • Becker Muscular dystrophy
• Toxic
  • Cocaine
  • Alcohol
  • Amphetamines
  • Heavy Metals
• Drug induced
  • Cardiotoxic drugs: Anthracyclines
  • AZT
• Endocrine/Metabolic
  • Thyroid disease
  • Pheochromocytoma
  • Acromegaly
  • Thiamine, Selenium, Carnitine, calcium deficiency
• Sustained Tachy arrhythmias : Afib
• Peripartum cardiomyopathy

Pathophysiology

• Primary myocardial insult causes reduced intrinsic contractility.
• Compensatory increase in preload (Frank-Starling) via increasing end-diastolic volume (EDV).
  • Initially, the sarcomeres stretch and increase the stroke volume.
• Persistent increased EDV causes Eccentric hypertrophy (sarcomeres in series). Typically starts in the left ventricle and left atrium.
• Progressive systolic dysfunction, caused by dilated and remodeled ventricles with decreased contractile efficiency, and increased wall stress (Laplace’s law).

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Risk Factors

• Male Sex
• Family History
• Moderate Alcohol use
• HTN
• Obesity
• Diabetes
• Pregnancy

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Differential Diagnosis

• Hypertrophic Cardiomyopathy
• Restrictive Cardiomyopathy
• Ischemic Cardiomyopathy

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Clinical Features

History

• Patients typically present with symptoms of Systolic Heart Failure :
  • Dyspnea
  • Fatigue
  • Exercise intolerance
  • Fluid retention

Physical Exam: Physical Exam Cardiology

Using IPASS Method

• Inspection
  • General appearance: Diaphoresis, pallor, tachypnea and Dyspnea at rest suggest decompensated heart failure. In athletes, unexplained exercise intolerance or fatigue disproportionate to conditioning level should raise suspicion.
  • Jugular venous distension (JVD): Elevated JVP is the most sensitive physical sign of congestion in heart failure and reflects elevated right atrial pressure. Assess with the patient at 45° — the top of the venous pulsation should normally be <3 cm above the sternal angle.
  • Precordial inspection: A visible, laterally displaced apical impulse or hyperactive precordium may indicate LV dilation. Surgical scars (sternotomy, thoracotomy) or device bulges (ICD/CRT) should be noted.
  • Peripheral inspection: Ankle/pedal edema, sacral edema (in supine patients), and abdominal distension suggest volume overload. Cool or mottled extremities indicate poor peripheral perfusion.
  • Connective tissue features: In younger athletes, inspect for stigmata of Marfan syndrome (tall stature, arachnodactyly, pectus deformity, hyperlaxity) — relevant because Marfan-associated cardiomyopathy can present as DCM.

• Palpation
  • Point of maximal impulse (PMI): Normally located at the 5th intercostal space, midclavicular line. In DCM, the PMI is characteristically diffuse and laterally displaced (inferolateral), reflecting LV dilation. As the ventricle assumes a spherical geometry, the impulse becomes broader and less forceful — in contrast to the sustained, forceful impulse of pressure-overloaded states (e.g., aortic stenosis).
  • Right ventricular heave/lift: A parasternal lift indicates RV pressure or volume overload, suggesting biventricular involvement or secondary pulmonary hypertension.
  • Thrills: Palpable vibrations over the precordium are uncommon in DCM because functional AV regurgitant murmurs are typically low-grade (≤2/6).
  • Peripheral pulses: Assess radial and femoral pulses simultaneously (to exclude coarctation in young athletes). A narrow pulse pressure (proportional pulse pressure ≤0.25) suggests reduced stroke volume. Pulsus alternans (alternating strong and weak beats) indicates severe LV dysfunction.
  • Hepatomegaly: Palpable, tender hepatomegaly — or pulsatile hepatomegaly — reflects hepatic congestion from right heart failure.

• Auscultation
  • S1: Often diminished in intensity due to reduced dP/dt (rate of pressure rise) from impaired LV contractility, and may also reflect prolonged PR interval (common in LMNA-related DCM).
  • S2: Assess for a loud P2 component, which indicates pulmonary hypertension secondary to elevated left-sided filling pressures. Paradoxical splitting of S2 may occur with LBBB (present in ~25% of DCM patients).
  • S3 (third heart sound): The hallmark auscultatory finding in DCM — a low-pitched sound in early diastole, best heard at the apex with the bell. It reflects rapid deceleration of blood entering a volume-overloaded, noncompliant ventricle and correlates with elevated filling pressures and reduced LVEF. An S3 is almost universally present in symptomatic DCM and carries prognostic significance — its persistence after treatment predicts higher readmission rates.
  • S4 (fourth heart sound): A presystolic sound reflecting atrial contraction against a stiff ventricle. Almost universally present in patients in sinus rhythm with DCM, though it is absent in atrial fibrillation.
  • Gallop rhythm: The combination of S3 + S4 (summation gallop), particularly with tachycardia, is a strong indicator of impending or active decompensation.
  • Heart Rate: Fast paced and irregular heart beats like indicative of A-fib
  • Murmurs of AV regurgitation:
    • Mitral regurgitation: Apical holosystolic (or sometimes mid-to-late systolic) murmur radiating to the axilla. In DCM, this is functional — caused by annular dilation and papillary muscle displacement rather than primary valve disease. Characteristically ≤grade 2/6 and may not be holosystolic.
    • Tricuspid regurgitation: Holosystolic murmur at the left lower sternal border. Notably, the usual inspiratory augmentation (Carvallo's sign is frequently absent in DCM).
  • Lung auscultation: Bilateral basilar crackles/rales indicate pulmonary edema, though rales may be absent in chronic compensated heart failure due to lymphatic adaptation.

Special Tests

• Abdominojugular reflux (hepatojugular reflux): Apply firm, sustained pressure over the right upper quadrant for 10–15 seconds while observing the JVP. A sustained rise of ≥4 cm indicates elevated left-sided filling pressures and is a useful bedside test for occult congestion.
• Valsalva maneuver: In DCM, the normal overshoot in phase IV (blood pressure rise above baseline after release) is blunted or absent, reflecting impaired cardiac reserve. This maneuver also helps differentiate functional MR murmurs (which decrease with Valsalva) from hypertrophic obstructive cardiomyopathy (which increases) — a critical distinction in the athlete.
• Orthostatic vital signs: Assess for orthostatic hypotension, which may reflect reduced cardiac output, over-diuresis, or autonomic dysfunction.
• Point-of-care ultrasound (POCUS): Increasingly recognized as the "fifth pillar" of the physical exam. The 2025 ACC/AHA guidelines include POCUS as a standard element of the cardiovascular physical examination, enabling bedside assessment of LV size and function, pericardial effusion, IVC collapsibility (volume status), and lung B-lines (pulmonary edema). For the sports medicine clinician, handheld ultrasound can rapidly differentiate athlete's heart from pathologic dilation at the point of care.
• Exercise provocation: In the sports medicine context, supervised exercise testing (treadmill or cycle ergometry with ECG monitoring) serves as a "special test" to unmask exercise-induced arrhythmias, assess chronotropic competence, and evaluate for failure of LVEF augmentation — all critical for return-to-play decisions.

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Evaluation

General

• Screening and detection in athletes is done during the pre-participation evaluations. It is imperative to get a thorough cardiovascular history, and do a good physical exam including a 12-lead ECG and Chest x-ray. History red flags to look out for exertional syncope, unexplained dyspnea or fatigue, and family history of DCM, SCD, or heart failure before age 50.
• If DCM is suspected, should get full workup.

Chest Radiograph

• Typically the first imagig study obtained
  • Often normal, especially in early or compensated dilated cardiomyopathy
• Potential findings include:
  • Cardiomegaly
  • Pulmonary vascular congestion
  • Interstitial/ Alveolar pulmonary edem
  • Pleural Effusion
  • Cephalization of pulmonary blood flow

Echocardiogram

• First line for assessing LV dilation and heart functioning

Cardiac MRI

• Needs to be updated

Event Monitor

• Needs to be updated

Laboratory

• Consider the following:
  • Brain Natriuretic Peptide (BNP)
  • Troponin
  • Thyroid Studies
  • Viral PCR
  • Irone Studies
  • Complete blood count
  • Complete metabolic panel

Genetic Testing

• Genetic Testing: Recommended for all patients with DCM, especially for those with familial disease or features suggestive of genetic etiology.
  • Should consider family screening echos for first-degree relatives

Biopsy

• Endomyocardial biopsy: When myocarditis, infiltrative diseases are suspected etiologies.

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Classification

• Needs to be updated

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Management

General

• Treat underlying and reversible causes
• Needs to be updated

Guideline Directed Medical Therapy (GDMT)

• Follow the Guideline Directed Medical Therapy (GDMT) for heart failure
• ARNI or ACE inhibitor or ARB
  • Sacubitril-Valsartan AKA Entresto, is the preferred ARNI
• Beta-blocker
  • Carvedilol
  • Metoprolol succinate
  • Bisoprolol
• Mineralocorticoid receptor antagonist
  • Spironolactone
  • Eplerenone
• SGLT2 inhibitor
  • Dapagliflozin
  • Empagliflozin

Initiation of all 4 class of medications/ quadruple therapy within the first 3 months is proven to be the most effective.

Device Therapy

• ICD: For primary prevention or should be considered if LVEF remains ≤35% after ≥3 months of optimized GDMT.
• Cardiac Resynchronization Therapy (CRT)

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Sports Participation and Return to Play

Participation

• Based on shared decision making.
• Genotype positive but phenotype negative, or people with the genetic disposition but without clinical disease, should be surveilled closely during play. Especially those in which phenotype conversion can be triggered by exercise, like in LMNA variant.
• Athletes with clinical disease should have extensive evaluation by specialist, be optimized on GDMT and have a shared decision making conversation/agreement, with the risks and benefits to playing being discussed in detail, before returning to play. Those with high risk features like LVEF <40%-45%, documented ventricular arrhythmia on holter or exercise stress test, high risk genotypes, unexplained syncope, late gadolinium, enhancement on CMR, warrant caution.

Return to Play

• Needs to be updated

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Prognosis and Complications

Prognosis

• Needs to be updated

Complications

• Heart Failure
• Arrhythmia
• Thromboembolism
• Syncope
• Sudden cardiac death

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See Also

• Cardiology Main
• Physical Exam Cardiology

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