RESTRICTIVE CARDIOMYOPATHY

Question 1

What is the basic pathophysiology in restrictive cardiomyopathy?

Answer 1

Increased stiffness of the ventricular walls leading to impaired diastolic filling of the ventricles.

Results in a steep rise in diastolic pressure with small increases in volume (preload). Ejection fraction is usually preserved in early stages.

Question 2

What are the main causes of restrictive cardiomyopathy?

Answer 2

Approximately half have identifiable causes, including:
* Myocardial infiltration from amyloidosis
* Sarcoidosis
* Gaucher’s disease
* Hurler’s disease
* Hemochromatosis
* Glycogen storage disease
* Fabry’s disease
* Hydroxychloroquine toxicity
* Radiation damage
* Anthracycline toxicity
* Endomyocardial fibrosis
* Secondary restrictive physiology from advanced heart disease.

Common in tropical regions, leading to higher incidence of endomyocardial fibrosis.

Question 3

What clues indicate the presence of restrictive cardiomyopathy?

Answer 3

Clues include:
* Definite heart failure with preserved ejection fraction (HFpEF)
* Kussmaul sign
* Low or normal voltage ECG with increased LV wall thickness
* LV hypertrophy without hypertension history
* Inability to up-titrate neurohormonal therapy
* History of down-titrating antihypertensive therapy.

Known risk factor for infiltrative/restrictive cardiomyopathies.

Question 4

What are the usual echocardiographic findings in restrictive cardiomyopathy?

Answer 4

Findings typically include:
* Normal or near-normal LV ejection fraction
* Normal or small ventricular volumes
* Increased ventricular wall thickness
* Impaired ventricular relaxation and filling
* Biatrial enlargement.

Tissue Doppler imaging may show reduced tissue velocities and longitudinal strain.

Question 5

How does amyloidosis affect the heart?

Answer 5

Leads to protein deposition in myocardial tissue, resulting in:
* Firm, rubbery, noncompliant myocardium
* Restrictive physiology
* Severely impaired longitudinal systolic function.

Common forms include primary (AL), familial, and senile cardiac amyloidosis.

Question 6

What are the red flags for diagnosing cardiac amyloidosis?

Answer 6

Red flags include:
* Low voltage ECG with thick LV
* Intolerance to beta-blockers or ACEI/ARB
* Low blood pressure in hypertensive patients
* History of bilateral carpal tunnel syndrome
* New diagnosis of hypertrophic cardiomyopathy in older patients.

Additional signs include macroglossia and peripheral neuropathy.

Question 7

What is the imaging modality of choice for active cardiac sarcoidosis?

Answer 7

Cardiac 18-fluoro-deoxyglucose positron emission tomography (FDG-PET).

It shows patchy abnormal uptake in affected myocardial segments.

Question 8

Is endomyocardial biopsy useful in suspected restrictive cardiomyopathy?

Answer 8

Yes, it is reasonable in unexplained restrictive cardiomyopathy associated with heart failure.

It is a class IIa, level of evidence C recommendation by ACC/AHA/ESC.

Question 9

What are typical echocardiographic features of cardiac amyloidosis?

Answer 9

Typical features include:
* Thickened ventricular walls
* Sparkling appearance on echocardiography
* Severely reduced tissue Doppler velocities.

Classic finding includes thickened walls with low voltage on ECG.

Question 10

What are the cardiac manifestations of sarcoidosis?

Answer 10

Manifestations include:
* Noncaseating granulomas infiltrating myocardium
* Heart block
* Syncope
* Ventricular arrhythmias.

MRI may reveal patchy delayed hyperenhancement.

Question 11

What is the significance of the lateral wall of the left ventricle in cardiac sarcoidosis?

Answer 11

It is indicative of active cardiac sarcoidosis.

Question 12

Is endomyocardial biopsy useful in cases of suspected restrictive cardiomyopathy?

Answer 12

Yes, it is considered reasonable in the setting of heart failure associated with unexplained restrictive cardiomyopathy.

Question 13

What can endomyocardial biopsy reveal in restrictive cardiomyopathy?

Answer 13

Specific disorders such as amyloidosis, hemochromatosis, myocardial fibrosis, and myocyte hypertrophy.

Question 14

When should endomyocardial biopsy not be performed?

Answer 14

If CT or MRI suggests constrictive pericarditis or if less invasive tests can diagnose a specific cause.

Question 15

Are cardiac CT and cardiac MRI useful in cases of restrictive cardiomyopathy?

Answer 15

Yes, they can demonstrate a thickened pericardium and specific disease patterns.

Question 16

What are hypereosinophilic syndrome and Loeffler’s disease characterized by?

Answer 16

Persistent marked eosinophilia and eosinophil-mediated end-organ damage.

Question 17

What is the most common cardiac manifestation of hypereosinophilic syndrome?

Answer 17

Endomyocardial fibrosis.

Question 18

What is Gaucher’s disease?

Answer 18

A disease characterized by deficiency of the enzyme b-glucocerebrosidase, resulting in cerebroside accumulation.

Question 19

How does Hurler’s syndrome affect the heart?

Answer 19

It leads to deposition of mucopolysaccharides in the myocardium, cardiac valves, and coronary arteries.

Question 20

What are the clinical features of restrictive cardiomyopathy?

Answer 20

Pulmonary/systemic congestion, dyspnea, low stroke volume symptoms, elevated jugular venous pulse, and possible Kussmaul sign.

Question 21

What drugs can cause restrictive cardiomyopathy?

Answer 21

Serotonin, methysergide, ergotamine, busulfan, mercurial agents, hydroxychloroquine, and chloroquine.

Question 22

What hemodynamic findings are seen on cardiac catheterization in restrictive cardiomyopathy?

Answer 22

Diastolic dip-and-plateau sign, difference between LV and RV diastolic pressure, and concordant pressure tracings.

Question 23

What is the 5-year survival rate for symptomatic patients with idiopathic restrictive cardiomyopathy?

Answer 23

64%.

Question 24

What are the treatment options for restrictive cardiomyopathy?

Answer 24

Treat underlying cause, use of loop diuretics, caution with heart rate-lowering agents, and consider cardiac transplantation.

Question 25

What is diabetic cardiomyopathy?

Answer 25

Ventricular dysfunction that occurs independently of coronary artery disease or hypertension.

Question 26

What are common findings on biopsy in diabetic cardiomyopathy?

Answer 26

Interstitial fibrosis, myocyte hypertrophy, glycosylation of contractile proteins, and collagen deposition.

Question 27

Fill in the blank: Endomyocardial biopsy should not be performed if CT or MRI suggests _______.

Answer 27

constrictive pericarditis.

Question 28

True or False: The pulse in restrictive cardiomyopathy may reflect low stroke volume with low amplitude and tachycardia.

Answer 28

True.

Question 29

What is the role of compression stockings in restrictive cardiomyopathy?

Answer 29

They can improve quality of life in patients with debilitating hypotension.