Lesson topic №28. Болезни миокарда (Myocarditis and Cardiomyopathy)

Restrictive cardiomyopathy

Restrictive cardiomyopathy: causes

Restrictive cardiomyopathy: epidemiology

RCM is a fairly rare disease, but it does account for approximately 5% of all cases of cardiomyopathy. It’s prevalence varies depending on regionality, ethnicity, age, and gender.

Amyloidosis: The most common cause of RCM in the United States. It affects men and women equally. AL-amyloidosis most common cause of RCM. The wild-type transthyretin amyloidosis is most often found in the elderly population. The V1221 mutant transthyretin has a higher rate of symptomatic heart failure.

Sarcoidosis: More common in women than men. The highest prevalence is among black women. The highest incidence worldwide is in Japan.

Hemochromatosis: Affects men and women equally. The prevalence is 1 per 200 individuals. Men are more likely to have cirrhosis associated with hemochromatosis. The predominant gene mutation HFE C282Y. It is inherited in an autosomal recessive pattern.

Loffler endocarditis: Common in tropical climates and sub-Saharan Africa. Up to twenty percent of heart failure in this region is thought to be secondary to endomyocardial fibrosis.

Restrictive cardiomyopathy: History and Physical

Patients with RCM primarily present with advanced disease and obvious signs of cardiopulmonary compromise, but in some circumstances, the diagnosis is incidental.

It is important to suspect RCM in any patient with a normal or close to normal systolic function and evidence of diastolic dysfunction with a restrictive filling pattern on echocardiogram.

For those that present symptomatically, there is a wide range of presentations. Some may present in full-blown heart failure (jugular venous distension, ascites, lower extremity edema, and less commonly pulmonary edema). Some may complain of poor exercise tolerance or be newly diagnosed with an arrhythmia such as atrial fibrillation.

Restrictive cardiomyopathy: History and Physical

When performing the evaluation and physical in a patient suspected of RCM, it is essential to look for extracardiac manifestations such as carpal tunnel, which may be present in amyloidosis or bilateral hilar infiltrates seen in sarcoidosis. Hemochromatosis may present with the classic bronze skin, cirrhosis, arthralgias, and endocrinopathies such as diabetes mellitus.

Restrictive cardiomyopathy: evaluation

Electrocardiogram (ECG) is one of the first tools used when a cardiac diagnosis is suspected. For example, a low-to-normal voltage in the QRS complex despite thickened cardiac muscle in the absence of valvular or hypertensive disease may lead one to suspect amyloidosis. However, the absence of low voltage does not exclude the diagnosis.

Complete heart block and right bundle branch bock are the most common presenting conduction abnormalities for patients with cardiac sarcoidosis, but all types of conduction abnormalities may occur. AV block may be the presenting sign of cardiac sarcoidosis. VT is the most common presenting arrhythmia, but supraventricular arrhythmias, frequent premature ventricular contractions, and ventricular fibrillation also occur before diagnosis.

Restrictive cardiomyopathy: evaluation

The echocardiogram is the primary diagnostic test for identifying patients with RCM. It may help aid in differentiating RCM from some of its common imitators, such as constrictive pericarditis. The echocardiogram may also provide information to suggest a specific diagnosis.

The first clue of restrictive pathophysiology is the combination of biatrial enlargement (which cannot be attributed to specific causes such as valve disease or AF), normal or mildly reduced LV and RV ejection fraction and non-dilated ventricles.

Doppler imaging can show a restrictive filling pattern of transmitral flow with increased early diastolic filling velocity (E wave) due to elevated left atrium (LA) pressure, and decreased atrial filling velocity (A wave) due to the high ventricular diastolic pressure, reduction of mitral deceleration time, and isovolumetric relaxation time.

Tissue Doppler typically shows reduced early diastolic myocardial velocity (e′) leading to an elevated E/e′ ratio.

Restrictive cardiomyopathy: evaluation

 Echocardiography in restrictive cardiomyopathies. (A) Small left ventricular cavity size in presence of significantly increased wall thickness and severe left atrial dilatation; (B) biventricular wall thickening in absence of pulmonary hypertension; (C and D) restrictive filling pattern with elevated E/E′ ratio in keeping with increased left ventricular filling pressures; (E) myocardial strain analysis showing an apical sparing pattern in a patient with cardiac amyloidosis.

Restrictive cardiomyopathy: evaluation

Whenever feasible, CMR should be part of the diagnostic work-up of patients with suspected RCM. For example in amyloidosis, where a gadolinium enhancement pattern is highly suggestive of amyloid.

Endomyocardial biopsy (EMB) may help establish the diagnosis in some cases if the primary workup has not been able to do so.

Restrictive cardiomyopathy: signs, symptoms and routine laboratory tests that raise the suspicion of specific aetiologies