A number of cardiac features may characterize a restrictive cardiomyopathy.
General features:
(1) preservation of left ventricular ejection fraction (LVEF) initially, but this deteriorates over time
(2) fixed stroke volume
(3) increased heart rate required to increase cardiac output
(4) hypotension during exercise
(5) pulmonary hypertension
(6) eventual development of right heart failure
On echocardiography:
(1) the left ventricle is rigid and noncompliant without dilatation
(2) there are elevated diastolic filling pressures with rapid equalization of filling pressure in all 4 chambers
(4) pressure tracings show a "dip and plateau" or "square root" pattern
(5) during inspiration there is an increase in the area of the right ventricular pressure curve
There is variation in the ECG changes depending on the underlying cause.
