Restrictive Cardiomyopathy Treatment & Management

With the possible exception of chelation therapy for hemochromatosis and corticosteroid therapy for sarcoidosis, restrictive cardiomyopathy (RCM) has no specific treatment. The mainstays of medical treatment include diuretics, vasodilators, and angiotensin-converting enzyme inhibitors (ACEIs) as indicated, as well as anticoagulation (if not contraindicated).^[9]

In selected patients, permanent pacing and transplantation (heart or heart-liver) may be considered.

The goal of treatment in RCM is to reduce symptoms by lowering elevated filling pressures without significantly reducing cardiac output. Presently, no drugs selectively enhance myocardial relaxation. Therefore, current therapy consists predominately of low-dose diuretics to lower the preload. Small initial doses should be administered to prevent hypotension because patients are frequently extremely sensitive to alterations in left ventricular volume. Higher doses may be needed if the serum albumin level is low secondary to concomitant nephrotic syndrome.

ACEIs and angiotensin II inhibitors are poorly tolerated in patients with amyloidosis. Even small doses may result in profound hypotension, probably secondary to an autonomic neuropathy. Beta-blockers and calcium channel blockers have not been shown to improve day-to-day symptoms or to favorably alter the natural history in patients with diastolic heart failure. No published data are available on the use of intravenous (IV) inotropic or vasodilator drugs.

Patients with a history of embolization or atrial fibrillation should be anticoagulated. In patients with atrial fibrillation, the rate should be controlled adequately. Removal of the atrial contribution to ventricular filling may worsen the existing diastolic dysfunction, and a rapid ventricular response may further compromise diastolic filling, creating a crisis. Therefore, maintaining sinus rhythm is important, and medications such as amiodarone and beta-blockers are often used.

Digoxin should be used with caution because it is potentially arrhythmogenic, particularly in patients with amyloidosis.

Antiplasma cell therapy with melphalan may slow the progress of systemic amyloidosis by stopping production of the paraprotein responsible for the formation of amyloid. The prognosis of patients with primary systemic amyloidosis remains poor, with a median survival of approximately 2 years despite intervention with alkylating-based chemotherapy in selected cases. In specific cases, chemotherapy has dramatic benefits, with improvement in systemic and cardiac manifestations.

The treatment of Loeffler endocarditis consists of correctly identifying the condition before the end-stage fibrosis occurs. Medical therapy with corticosteroids, cytotoxic agents (eg, hydroxyurea), and interferon to suppress the intense eosinophilic infiltration of the myocardium is appropriate during the early phase of Loeffler endocarditis and improves symptoms and survival. Conventional heart failure medication is also given.

Chelation therapy or venesection is effective in patients with hemochromatosis to decrease the iron overload.

Patients with idiopathic restrictive cardiomyopathy (RCM) may have fibrosis of the sinoatrial and atrioventricular nodes that result in complete heart block, and, therefore, require permanent pacing. If cardioversion to treat atrial fibrillation is attempted, particularly in patients with amyloidosis, the abnormal sinus node may fail as an effective pacemaker. Patients with sinus node dysfunction and/or advanced conduction system disease also require treatment with implantation of a pacemaker.

As noted, treatment of Loeffler endocarditis depends on correctly identifying the condition before the end-stage fibrosis occurs and typically involves early pharmacotherapy (see Pharmacologic Therapy).

In the fibrotic stage of Loeffler endocarditis, surgical therapy, with excision of the fibrotic endocardium and replacement of the mitral and tricuspid calves, is palliative but may provide symptomatic improvement. The operative mortality is in the range of 15-25%.

Cardiac transplantation can be considered in highly selected patients with refractory symptoms who have idiopathic or familial RCM and amyloidosis. When noncardiac organ involvement is absent, a few patients with amyloidosis have undergone successful cardiac transplantation, combined with postoperative high-dose chemotherapy, to abolish recurrent amyloid production.

Combined heart and liver transplantation in patients with heart and liver failure due to hemochromatosis has been successful in small numbers of patients. However, early morbidity and mortality are higher in dual-organ transplantation than in single-organ transplantation.

Transplantation is a treatment option for cardiac sarcoidosis, but recurrence of sarcoid granulomas can occur in the transplanted heart.

A surgical approach offers a cure for pericardial constriction but carries a potential for significant morbidity for RCM. Thus, establishing a clear diagnosis is crucial, and the advent of current sophisticated imaging technology helps in that regard (see Workup). Fewer patients now need exploratory open-heart surgery to establish the correct diagnosis.

Stem cell transplantation used in conjunction with high-dose chemotherapy is still considered experimental by most cardiologists. Its routine use has not yet been established.

Finally, whether patients who have radiation-induced cardiac diseases are candidates for heart transplant is uncertain. Concerns have been raised as to whether their immune system would allow them to receive the immunosuppressive therapy necessary after the surgical procedure and whether relapse of their malignancy might occur.