Restrictive cardiomyopathy

Restrictive cardiomyopathy (RCM) is a form of cardiomyopathy in which the walls of the heart are rigid (but not thickened). Thus the heart is restricted from stretching and filling with blood properly. It is the least common of the three original subtypes of cardiomyopathy: hypertrophic, dilated, and restrictive.

It should not be confused with constrictive pericarditis, a disease which presents similarly but is very different in treatment and prognosis.

Untreated hearts with RCM often develop the following characteristics:

Those affected by RCM will experience decreased exercise tolerance, fatigue, jugular venous distention, peripheral edema, and ascites. Arrhythmias and conduction blocks are common.

RCM can be caused by genetic or non-genetic factors. Thus it is possible to divide the causes into primary and secondary. The common modern organization is into Infiltrative, storage diseases, non-infiltrative, and endomyocardial etiologies:

The most common cause of restrictive cardiomyopathy is amyloidosis.

Rhythmicity and contractility of the heart may be normal, but the stiff walls of the heart chambers (atria and ventricles) keep them from adequately filling, reducing preload and end-diastolic volume. Thus, blood flow is reduced, and blood volume that would normally enter the heart is backed up in the circulatory system. In time, restrictive cardiomyopathy patients develop diastolic dysfunction and eventually heart failure.

Diagnosis is typically made via echocardiography. Patients will demonstrate normal systolic function, diastolic dysfunction, and a restrictive filling pattern. 2-dimensional and Doppler studies are necessary to distinguish RCM from constrictive pericarditis. If a patient has restrictive cardiomyopathy, the Doppler study should present poorly maintained ventricular filling on the E-wave and little to no late ventricular filling on the A-wave leading to the dip and plateau pattern of the early diastolic pressure marks seen on the ECG. Troponin T, B-type natriuretic peptide (BNP), and pro-DNP biomarkers can also help diagnose RCM. Cardiac MRI and transvenous endomyocardial biopsy may also be necessary in some cases. Reduced QRS voltage on EKG may be an indicator of amyloidosis-induced restrictive cardiomyopathy.