The heart in sarcoidosis

Associate Editor:

Assistant Editor: Brian Blank

Overview
Pericarditis as a manifestation of sarcoidosis has been frequently described and necropsy studies have documented cardiac involvement in 27% of patients, but clinically significant pericarditis is uncommon. In addition, sarcoidosis has been rarely documented in children.

The granulomatous infiltrative disease of the myocardium is often asymptomatic, but can cause arrhythmias, conduction disease and, rarely, otherwise unexplained congestive heart failure. Early diagnosis can be very important because it's generally believed aggressive steroid treatment may decrease mortality. Granulomatous infiltration may be patchy, with a predilection toward involvement of the left ventricle, particularly the upper septal area. This distribution influences the likelihood of obtaining a diagnostic right sided endomyocardial biopsy. Use of gallium or thallium imaging may be helpful in determining the need for and duration of immunosuppressive therapy, but this approach has not been proved in any formal trial.

Sarcoid dilated cardiomyopathy may be difficult to distinguish from idiopathic cardiomyopathy or occasionally from giant cell myocarditis.

Conduction disease is more common than pump dysfunction in patients with sarcoidosis. Biopsy may help distinguish sarcoidosis from idiopathic or giant cell myocarditis, but the diagnostic yield of endomyocardial biopsy is low.

Active sarcoidosis is generally believed to be steroid responsive. However, myocardial involvement with sarcoid can result in large patches of fibrotic scar that may be arrhythmogenic but no longer respond to steroids. Scar is often significantly underestimated by imaging studies and biopsy.

Pulmonary artery hypertension and cor pulmonale can occur in sarcoidosis, generally as a result of pulmonary fibrosis.

Systemic vasculitis is an uncommon complication of sarcoidosis. Its prevalence remains unknown. Sarcoid vasculitis can affect small to large caliber vessels, including the aorta. The latter presentation can be easily confused with Takayasu arteritis. African American patients appear predisposed to developing large vessel involvement.

Cardiac MRI
Common MRI findings in patients with cardiac sarcoidosis include:
 * Delayed enhancement, which may be either mid wall or transmural
 * Nodular mid wall hyperintense foci on black blood T2-weighted imaging
 * Areas of focal myocardial thickening.
 * Disease may involve either the left or the right ventricle but more commonly involves the left ventricle.