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Dr. Sharma is Professor of Medicine, Keck School of Medicine.
Correspondence to: Om P. Sharma, MD, Room 11-900, LAC + USC Medical Center, 1200 North State St, Los Angeles, CA 90033; e-mail: osharma{at}hsc.usc.edu
Bernstein et al1 were the first to recognize cardiac sarcoidosis. Gozo and associates2 were the first to give us the clinical and pathologic description. Hagemann and Wurm3 estimated that the heart was affected in about 5% of patients with chronic sarcoidosis. Later on, autopsy studies indicated that the incidence of subclinical sarcoidosis was much higher than previously realized.4 In a report from Johns Hopkins Hospital (Baltimore, MD),5 myocardial granulomas were seen in 27% of patients, and in 37% of the patients with cardiac involvement there were no clinical signs or symptoms of heart disease. Granulomatous lesions in the heart were found in 24 of 123 patients (19.5%) with sarcoidosis who had autopsies performed at Los Angeles County + University of Southern California Medical Center (Los Angeles, CA).6 The prognosis for patients with clinically diagnosed cardiac sarcoidosis has not been well-investigated.7 Roberts et al8 concluded that survival in most patients was limited to 2 years after the development of cardiac symptoms and signs. Flemming and Bailey9 were a bit more optimistic when they reported that 44% of their series of 250 patients survived for > 5 years. Thus, the prognosis for patients with sarcoidosis was considered dismal. Nevertheless, many of these pessimistic pronouncements were made before the advent of the automatic implantable defibrillator, refined diagnostic techniques, and aggressive use of corticosteriod, immunosuppressive, and immune modulator agents.10 11 In any case, in order to increase the survival time of patients with myocardial sarcoidosis, two requirements need to be fulfilled. The diagnosis should be established early and accurately, and the treatment should be aggressive and effective. In the present state of knowledge, both of these conditions have remained only partially realized.
The diagnosis of myocardial sarcoidosis is difficult and frustrating. Its clinical manifestations depend on the location and extent of granulomatous inflammation, and the symptoms and signs range among benign arrhythmias, heart block, intractable heart failure, intense chest pain, to fatal ventricular fibrillation. Furthermore, cardiac involvement may proceed, follow, or occur concurrently with involvement of the lungs or other organs. If cardiac manifestation occurs in a patient with multisystem sarcoidosis, the diagnosis, although circumstantial, is relatively clear. However, when cardiac dysfunction is the sole manifestation of sarcoidosis, the diagnosis is not entertained, and even if the diagnosis is contemplated, it is usually not confirmed because of the unavailability of specific diagnostic tests.
The ECG finding may be normal or may reflect every degree of block and every type of arrhythmia along with nonspecific ST-T-wave changes.9 In one study,12 38 consecutive patients with biopsy-proven sarcoidosis received 24-h Holter monitoring. More than 10 supraventricular ectopic beats occurred in 8 of 12 patients (66.7%) with clinical cardiac sarcoidosis, in 7 of 26 patients (26.9%) with no clinical evidence of cardiac sarcoidosis, and in 3 of 58 healthy control subjects (5%). An ECG or Holter abnormality should be investigated further by a two-dimensional echocardiography to detect structural and functional changes due to granuloma formation and fibrosis.13 Since sequential contraction may be missed with two-dimensional echocardiography, the next step is to perform 201Tl imaging. The fibrogranulomatous lesions of the myocardium display segmental areas of decreased 201Tl uptake.14 During exercise or after the administration of dipyridamole, these perfusion defects may disappear or may decrease in size. This phenomenon, called reverse distribution, helps to differentiate the granulomatous nature of the injury from the one caused by coronary artery disease.15 16 A coronary angiogram often is required. In the presence of healthy coronary arteries, the perfusion defects on 201Tl imaging in a patient with known multisystem sarcoidosis strongly suggest myocardial involvement. Unfortunately, a normal finding on the 201Tl scan does not exclude the presence of cardiac involvement.17 A positive finding on the 201Tl scan also has no prognostic value.18 The combination of 201Tl and 67Ga scanning has been reported to provide more information.19 Although radionuclide studies are useful in the patients in whom cardiac sarcoidosis is suspected, their value as screening tests has not been established.20
Matsuki and Matsuo21 pointed out the usefulness of MRI in diagnosing and monitoring patients with cardiac sarcoidosis. Granulomatous infiltrates appear on MRI images as areas of increased signal density. T2-weighted images tend to produce a more pronounced signal because of the associated edema. These images can be enhanced with gadolinium diethylenetriamine pentaacetic acid.22 23 The accurate localization of a granulomatous lesion by MRI can be used as a guide to obtaining an endomyocardial biopsy specimen.21 In the December 2002 issue of CHEST, Vignaux and associates24 used MRI as a method of evaluating and monitoring cardiac sarcoidosis in 12 sarcoidosis patients. All patients had undergone extensive cardiac evaluations, including an ECG, 24-h Holter monitoring, echocardiography, 201Tl imaging, cardiac MRI, and coronary angiography, if indicated. An endomyocardial biopsy specimen was not obtained in any patient. MRI abnormalities, consisting of cardiac signal intensity and thickness, were grouped in the following three patterns: nodular; focal increase in signal on gadolinium diethylenetriamine pentaacetic acid-enhanced, T1-weighted images; and focal increased signal on T2-weighted images without gadolinium uptake. The MRI images that were obtained initially and at the 12-month follow-up interval were interpreted by two independent cardiovascular radiologists. Scores ranging from -1 to +1 were assigned to six different myocardial areas. The improvement or stability of the MRI findings was correlated with clinical features. In six patients who had received corticosteroid therapy, the MRI images improved either partially or completely, whereas, the images from the patients who had received no corticosteroid therapy either worsened or remained unchanged. The study is small and lacks a correlation of myocardial histology with MRI features. However, the study clearly calls for a large multicenter trial. The cardiac MRI may find its usefulness as a guide to obtaining endomyocardial biopsy specimens and to monitoring the response of the disease to treatment. The most significant drawback of MRI is that the patient with a pacemaker and/or automatic implantable cardioverter defibrillator will not be able to take advantage of it. In such patients, 201Tl scanning remains the test for assessing myocardial damage. An endomyocardial biopsy is preferable, but the procedure has a sensitivity as low as 20%.25 Thus, the search for a safe, reliable, and easily available diagnostic test for cardiac sarcoidosis continues.
References
This article has been cited by other articles:
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  A. Nakazawa, K. Ikeda, Y. Ito, M. Iwase, K. Sato, R. Ueda, and Y. Dohi Usefulness of Dual 67Ga and 99mTc-Sestamibi Single-Photon-Emission CT Scanning in the Diagnosis of Cardiac Sarcoidosis Chest, October 1, 2004; 126(4): 1372 - 1376. [Abstract] [Full Text] [PDF]
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