Cardio: cardiomyopathy

What is cardiomyopathy?

Myocardial disorders in which the heart muscle is structurally and functionally abnormal. Causes may be genetic, acquired, or mixed.

What is the difference between primary and secondary cardiomyopathy?

Primary = disease process is chiefly confined to the heart. Secondary = cardiac involvement occurs as part of a systemic condition.

What are the 3 major types of cardiomyopathy?

Dilated = distended heart muscle; Restrictive = stiff/"rock-hard" heart that cannot refill properly; Hypertrophic = abnormally thick/large heart muscle that may restrict the aorta.

What is restrictive cardiomyopathy (RCM)?

A rare cardiomyopathy in which the heart muscle is stiff with decreased compliance but is not necessarily thickened. This causes impaired ventricular filling during diastole.

What happens to systolic function and EF in restrictive cardiomyopathy?

Systolic function is usually preserved early, and EF is normal or mildly reduced.

What chamber changes are characteristic of restrictive cardiomyopathy?

Marked biatrial enlargement occurs because of chronically elevated filling pressures; ventricular cavities are normal or small.

What is the main pathophysiology of restrictive cardiomyopathy?

The ventricles cannot relax properly → impaired diastolic filling → diastolic heart failure → blood backs up, causing venous congestion and decreased cardiac output.

What mnemonic can be used for major causes of restrictive cardiomyopathy?

SHAPE: Sarcoidosis, Hemochromatosis, Amyloidosis, Post-radiation fibrosis, Endomyocardial fibrosis.

What is the most common cause of restrictive cardiomyopathy?

Amyloidosis.

What are causes of restrictive cardiomyopathy?

Amyloidosis, sarcoidosis, Loeffler endocarditis, hemochromatosis, radiation/chemotherapy, endomyocardial fibrosis, carcinoid syndrome, and familial/genetic disease.

How does amyloidosis cause restrictive cardiomyopathy?

Abnormal proteins misfold, become insoluble, and deposit between myocardial cells → stiff, noncompliant ventricles → impaired diastolic filling → restrictive cardiomyopathy.

What is amyloidosis?

An infiltrative disorder caused by deposition of amyloid fibrils in extracellular tissues, including the heart, kidney, liver, nerves, bone marrow, fat, and skin.

What are the major types of amyloidosis?

AL = primary amyloidosis from immunoglobulin light chains; AA = secondary amyloidosis from chronic inflammatory disease; ATTR = wild-type associated with aging or mutant protein in familial forms.

What is the most common cause of cardiac amyloidosis?

ATTR amyloidosis; it is increasingly recognized in older adults with HFpEF and unexplained LV wall thickening.

How does restrictive cardiomyopathy usually present?

Progressive heart failure symptoms over months to years, usually right-sided > left-sided.

What are signs and symptoms of restrictive cardiomyopathy?

Fatigue, dyspnea, peripheral edema, elevated JVP, ascites, hepatomegaly, decreased exercise tolerance, palpitations, syncope, angina, S3/S4 gallop, and possible stroke from AF or thromboembolism.

What systemic findings suggest amyloidosis in a patient with restrictive cardiomyopathy?

Peripheral neuropathy, periorbital purpura, macroglossia, and unintentional weight loss.

What ECG findings may occur with restrictive cardiomyopathy?

Low-voltage QRS, especially with cardiac amyloidosis; conduction abnormalities and atrial fibrillation may also occur.

What is the first-line diagnostic test for restrictive cardiomyopathy?

Echocardiogram.

What are echocardiographic findings in restrictive cardiomyopathy?

Biatrial enlargement, normal or mildly increased ventricular wall thickness, normal/small ventricular cavities, preserved or mildly reduced LVEF, severe diastolic dysfunction, and elevated filling pressures.

What is the role of cardiac MRI in restrictive cardiomyopathy?

Helps identify infiltrative diseases, especially amyloidosis and sarcoidosis.

What is the diagnostic gold standard for restrictive cardiomyopathy when the etiology remains uncertain?

Endomyocardial biopsy, although it is rarely required if noninvasive testing is diagnostic.

What does Pulmonary capillary wedge pressure PCWP indirectly reflect?

Left atrial pressure and therefore left ventricular filling pressure.

How is restrictive cardiomyopathy treated?

Treat the underlying cause, use gentle loop diuretics for congestion, maintain sinus rhythm when possible, anticoagulate AF, provide etiology-specific therapy, and refer to cardiology.

Why must diuretics be used cautiously in restrictive cardiomyopathy?

Patients depend on adequate filling pressures; excessive preload reduction can worsen cardiac output.

Are beta-blockers and verapamil routinely used in restrictive cardiomyopathy?

No. They may worsen symptoms because patients have a relatively fixed stroke volume.

Why is rhythm control generally preferred over rate control in restrictive cardiomyopathy?

Atrial contraction contributes significantly to ventricular filling.

How is ATTR cardiac amyloidosis treated?

Tafamidis is standard therapy for ATTR cardiac amyloidosis.

How are sarcoidosis and Loeffler-related restrictive cardiomyopathy treated?

Corticosteroids.

What is hypertrophic cardiomyopathy (HCM)?

A genetic disorder characterized by abnormal thickening of the LV wall, typically asymmetric hypertrophy.

What is the epidemiology of hypertrophic cardiomyopathy?

Genetic heart disease with a prevalence historically estimated around 1 in 500, with newer estimates around 1 in 200; usually presents in early adulthood.

When should hypertrophic cardiomyopathy be suspected based on LVH?

When LVH is present without another identifiable cause.

What inheritance pattern is associated with hypertrophic cardiomyopathy?

Autosomal dominant.

What does autosomal dominant inheritance mean for the child of an affected parent?

A child has a 50% chance of inheriting the affected allele.

What are the major pathophysiologic abnormalities in hypertrophic cardiomyopathy?

LV hypertrophy, LV outflow obstruction in about 2/3 of cases, diastolic dysfunction, myocardial ischemia, mitral regurgitation, and predisposition to arrhythmias.

What happens to LV volume in hypertrophic cardiomyopathy?

LV volume is average or reduced because the thick, stiff, less compliant ventricle has impaired diastolic filling.

What part of the heart is most commonly asymmetrically hypertrophied in HCM?

The interventricular septum.

What major life-threatening complication is associated with HCM?

Sudden cardiac death; HCM is the most common cause of sudden cardiac death in athletes.

How may hypertrophic cardiomyopathy first present?

Patients are frequently asymptomatic, and cardiac arrest may be the first presentation.

What symptoms occur with hypertrophic cardiomyopathy?

Exertional chest pain, exertional dyspnea, syncope/presyncope, palpitations, arrhythmias, and sudden death.

When should HCM be considered in children?

Any child with exertional cardiac complaints, particularly exertional syncope, chest pain, or dyspnea.

What physical exam findings are associated with HCM?

Sustained PMI, S4 gallop, harsh crescendo-decrescendo systolic murmur at the left lower sternal border, and sometimes a bifid carotid pulse.

What happens to the HCM murmur with Valsalva or standing?

It becomes LOUDER because decreased preload decreases LV chamber volume and worsens LVOT obstruction.

What happens to the HCM murmur with squatting?

It becomes SOFTER because increased LV volume/preload reduces the obstruction.

What happens to the HCM murmur with handgrip?

It becomes softer because increased afterload reduces the dynamic LVOT obstruction.

What is a bifid carotid pulse in HCM?

A carotid pulse with two peaks during one heartbeat because blood flow is briefly slowed by LVOT obstruction and then rises again later in systole.

What is the general rule for maneuvers and the HCM murmur?

Decreased LV volume → increased murmur; increased LV volume → decreased murmur.

What ECG findings are associated with hypertrophic cardiomyopathy?

LVH and deep, narrow "dagger-like" Q waves; atrial fibrillation or ventricular arrhythmias may also occur.

What is the first-line diagnostic test for HCM?

Echocardiogram.

What echocardiographic findings suggest hypertrophic cardiomyopathy?

LV wall thickness ≥15, asymmetric septal hypertrophy, systolic anterior motion (SAM) of the mitral valve, dynamic LVOT obstruction, and diastolic dysfunction.

What is systolic anterior motion (SAM) of the mitral valve?

The anterior mitral leaflet abnormally moves toward the LVOT during systole → partially obstructs the LVOT and can cause mitral regurgitation.

What is the role of cardiac MRI in HCM?

Defines myocardial hypertrophy and fibrosis and is used when echo is inconclusive or for risk stratification.

What additional testing may be used in HCM?

Ambulatory ECG/Holter to detect arrhythmias and exercise stress testing to assess LVOT obstruction, BP response, and exercise tolerance.

What is first-line pharmacologic treatment for HCM?

Beta-blockers such as metoprolol, atenolol, or propranolol.

Why are beta-blockers used in HCM?

They slow heart rate and decrease contractility → improve ventricular filling and reduce LVOT obstruction.

What can be used if a patient with HCM cannot tolerate a beta-blocker?

Verapamil or diltiazem.

What medication should be avoided in HCM because it may worsen LVOT obstruction?

Digoxin.

How is atrial fibrillation managed in HCM?

Maintain sinus rhythm when possible and anticoagulate patients with AF.

What are exercise recommendations for HCM?

Regular exercise is encouraged, with shared decision-making regarding vigorous or competitive sports.

Who with HCM may require an ICD?

Patients at high risk of sudden cardiac death.

When is septal reduction therapy considered in HCM?

Persistent severe symptoms despite optimal medical therapy.

What is the gold-standard septal reduction procedure for HCM?

Surgical septal myectomy.

What happens during surgical septal myectomy?

A portion of the hypertrophied interventricular septum is removed to reduce LVOT obstruction.

What happens during alcohol septal ablation for HCM?

Alcohol is injected into a septal branch of the LAD to create a controlled infarction and reduce LVOT obstruction.

When is heart transplantation considered in HCM?

Rarely, for end-stage HCM with refractory heart failure.

What family screening is recommended for HCM?

Screen first-degree relatives and refer patients to cardiology/an HCM center.

How does pregnancy affect patients with HCM?

Risk increases in patients with symptoms or LVOT gradients >50 mm Hg; genetic counseling is indicated before planned conception, and beta-blocker therapy should be continued during pregnancy.

What is dilated cardiomyopathy (DCM)?

A cardiomyopathy characterized by LV or biventricular dilation, thin walls, impaired systolic function, and reduced LVEF.

What is the most common form of cardiomyopathy?

Dilated cardiomyopathy, accounting for approximately 95% of cardiomyopathy cases in the lecture.

What EF pattern occurs in dilated cardiomyopathy?

Reduced LVEF consistent with HFrEF, typically ≤40%.

Who commonly develops dilated cardiomyopathy?

It typically presents between ages 20-60 but can occur at any age and is more common in Black patients and males.

What complications are associated with dilated cardiomyopathy?

Heart failure, functional valve regurgitation, atrial and ventricular arrhythmias, and sudden cardiac death.

What is the most common overall listed cause of DCM?

Idiopathic disease, accounting for approximately 40-50%.

What is the most common acquired cause of dilated cardiomyopathy?

Ischemic heart disease from post-MI remodeling or chronic CAD.

What is the most common infectious cause of dilated cardiomyopathy?

Viral myocarditis.

What infectious diseases can cause dilated cardiomyopathy?

Viral infections, HIV, Lyme disease, Chagas disease, and COVID.

What toxins can cause dilated cardiomyopathy?

Alcohol, cocaine, methamphetamine, and chemotherapy.

What other conditions can cause dilated cardiomyopathy?

Stress-induced disease, genetic/familial disease, DM, thyroid disease, tachycardia-induced cardiomyopathy, amyloidosis, sarcoidosis, peripartum cardiomyopathy, nutritional deficiencies, HIV, iron overload, OSA, and end-stage kidney disease.

What nutritional deficiencies can cause dilated cardiomyopathy?

Thiamine ("wet beriberi"), selenium, and carnitine deficiencies.

What is the pathophysiology of dilated cardiomyopathy?

Myocyte injury → ventricular remodeling → chamber dilation and wall thinning → reduced contractility → decreased EF and cardiac output → RAAS/SNS activation → progressive HF, functional MR, and ventricular arrhythmias.

Why can dilated cardiomyopathy cause mitral or tricuspid regurgitation?

Dilation stretches/pulls on the valve annulus, producing functional regurgitation.

What symptoms occur with dilated cardiomyopathy?

Progressive DOE, orthopnea, PND, fatigue, weakness, reduced exercise tolerance, and late peripheral edema.

What physical exam findings occur with DCM?

Sinus tachycardia, displaced/diffuse PMI, S3 gallop, pulmonary rales when volume overloaded, elevated JVP, peripheral edema, and a functional holosystolic MR/TR murmur.

What initial laboratory studies are used when evaluating DCM?

BNP or NT-proBNP, CBC, CMP, and TSH.

What ECG findings may occur in DCM?

Sinus tachycardia, LBBB/conduction abnormalities, LVH, nonspecific ST-T changes, and atrial or ventricular arrhythmias.

What chest X-ray findings may occur in DCM?

Cardiomegaly, pulmonary edema, and pleural effusions.

What is the first-line diagnostic test for suspected dilated cardiomyopathy?

Transthoracic echocardiogram.

What echocardiographic findings occur in DCM?

LV dilation, global hypokinesis, reduced LVEF, and functional mitral/tricuspid regurgitation.

When is coronary angiography used in DCM?

To evaluate for ischemic cardiomyopathy.

When is right heart catheterization used in DCM?

For advanced heart failure or hemodynamic assessment.

When is cardiac MRI useful in DCM?

To evaluate myocarditis, infiltrative cardiomyopathy such as amyloidosis or sarcoidosis, and myocardial scar/fibrosis.

How is dilated cardiomyopathy with HFrEF treated?

With the four pillars of guideline-directed medical therapy: ARNI/ACEi/ARB, evidence-based beta-blocker, MRA, and SGLT2 inhibitor.

What is the preferred RAAS-related therapy in DCM/HFrEF?

ARNI is preferred when tolerated; sacubitril/valsartan is the listed ARNI.

Which beta-blockers are evidence-based for HFrEF?

Carvedilol, metoprolol succinate, and bisoprolol.

Which MRAs are used in HFrEF?

Spironolactone or eplerenone.

Which SGLT2 inhibitors are used in HFrEF?

Dapagliflozin or empagliflozin.

Do patients need diabetes to receive an SGLT2 inhibitor for HFrEF?

No. SGLT2 inhibitors are recommended regardless of diabetes status.

How should the four pillars of HFrEF therapy be initiated?

Initiate all four classes early and titrate to maximally tolerated doses.

Why are calcium channel blockers generally avoided in HFrEF/DCM?

Negative inotropic effect.

What is stress cardiomyopathy also called?

Takotsubo cardiomyopathy or "broken heart syndrome."