Restrictive cardiomyopathy - Disorders of the myocardium

Restrictive cardiomyopathy

Definition

Restrictive or infiltrative cardiomyopathy is a rare disorder of cardiac muscle resulting in restricted ventricular filling.

Aetiology

Amyloidosis, scleroderma, sarcoidosis, iron storage diseases (haemochromatosis) and eosinophilic heart disease (endomyocardial fibrosis and Loefller’s eosinophilic endocarditis).

Pathophysiology

Infiltrative disease causing a decrease in ventricular compliance (increase in stiffness) affecting the myocardium. The result is a failure of relaxation during diastole, impairment of ventricular filling and compromise of cardiac output. Valves may also be affected by the underlying disease.

Clinical features

Patients present in a similar way to constrictive pericarditis with a tachycardia, raised JVP with steep x and y descents. There may be a third heart sound due to abrupt ventricular filling. Enlarged liver, ascites and peripheral oedema may all be seen.

Complications

Thrombus formation is common, and arrhythmias and sudden death occur.

Investigations

Chest X-ray frequently shows cardiac enlargement, echo shows symmetrical myocardial thickening, normal ejection fraction but impaired filling. Differentiation from constrictive pericarditis using these methods can be difficult. Definitive diagnosis may require cardiac catheter-isation and cardiac biopsy. Alternatively amyloid may be diagnosed in other organs or using a serum amyloid protein (SAP) scan.

Management

No specific treatment. Low-dose diuretics and vasodilators may provide some relief from symptoms. Patients with eosinophilic heart disease may benefit from treatment with steroids and cytotoxic drugs.

Prognosis

The condition is commonly progressive.