Published in:
01-06-2014 | Images That Teach
Role of multimodality imaging in the early identification of cardiac sarcoidosis
Published in: Journal of Nuclear Cardiology | Issue 3/2014
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A 40-year-old male presented to the emergency department complaining of palpitations and was found to be in stable monomorphic ventricular tachycardia (Figure 1). He underwent a thorough diagnostic workup. Cardiac catheterization revealed normal coronary arteries and endomyocardial biopsy was nondiagnostic. However, based on findings from multiple imaging modalities including cardiac MRI (Figure 2), transthoracic echocardiography (Figure 3A), and cardiac PET (Figure 4, first and second rows; and Figure 5), a clinical diagnosis of cardiac sarcoidosis was made. High-dose steroids were initiated and he underwent placement of an ICD before discharge. After completing a course of steroids, repeat imaging revealed improved left ventricular function and resolution of regional cardiac inflammation (Figure 3B; and Figure 4, third row). The patient continues to do well clinically with no symptoms or arrhythmias.
Figure 1
EKGs upon presentation to emergency department and admission to CCU. (A) Upon presentation to the emergency department, the patient had a heart rate of 205 beats·minute−1 and a blood pressure of 115/79. His 12-lead EKG suggested ventricular tachycardia (VT) of right ventricular outflow tract origin. (B) After administration of intravenous amiodarone, the ventricular tachycardia terminated, and the patient returned to a normal sinus rhythm. Repeat EKG performed at time of admission to the CCU demonstrated normal sinus rhythm with nonspecific ST-T abnormalities. Initial troponin-I was 1.56 ng·mL−1 and peaked at 3.08 ng·mL−1. Given the mildly elevated troponin and ventricular arrhythmia at presentation, the patient underwent cardiac catheterization to exclude obstructive coronary artery disease. Cardiac catheterization revealed normal coronary arteries (not shown)
Figure 2
Cardiac MRI prior to steroid treatment demonstrated an area of delayed enhancement on the right ventricular side of the mid to apical interventricular septum, as well as mediastinal lymphadenopathy. Serum angiotensin converting enzyme (ACE) level was elevated at 83 U·L−1 (reference range 9-67 U·L−1). These findings were suspicious for sarcoidosis with cardiac involvement. The patient was started empirically on steroids, 500 mg IV methylprednisolone BID for 6 doses, followed by 60 mg of oral prednisone daily, as well as Bactrim DS three times a week for PCP prophylaxis and famotidine for GI prophylaxis. Endomyocardial biopsy showed mild to moderate myocyte hypertrophy and mild thickening of small arteries with scant interstitial fibrosis, but did not show noncaseating granulomas, the characteristic finding of sarcoidosis
Figure 3
Initial and follow-up echocardiograms. (A) Initial transthoracic echocardiogram revealed a left ventricular ejection fraction of 40%-45% with global hypokinesis, and a homogeneous echodense material of unclear etiology on the right ventricular side of the interventricular septum. The patient was started on an ACE inhibitor for the left ventricular systolic dysfunction. As he initially had short runs of nonsustained ventricular tachycardia during his hospitalization, oral amiodarone was continued and the patient was started on a beta-blocker. After 3 months, his steroids were tapered off, and the beta-blocker and ACE inhibitor doses decreased. (B) Transthoracic echocardiogram after steroid and standard heart failure treatment shows an improved left ventricular ejection fraction of 50%-55% and resolution of the echodense material in the septal region noted on the initial echocardiogram
Figure 4
Cardiac PET scans before and after steroid therapy. Rest myocardial perfusion was performed using SPECT Tc-99m sestamibi. PET images were acquired on a Siemens Biograph-40 Truepoint PET/computed tomography (CT) scanner (Siemens, Hoffman Estates, IL). A CT attenuation scan was performed (25 mA, 120 kV) with a pitch of 1.5 covering the region of interest (ROI) in 3.3 seconds during shallow breathing. An emission scan was acquired in list mode for 10 minutes starting at time of injection. The patient received approximately 10 mCi of F18-FDG by intravenous injection followed by a waiting period of 90 minutes before repeat scanning. In order to suppress physiologic glucose uptake by the heart, patients were instructed to avoid carbohydrates for 24 hours prior to imaging. In each row in this figure, the first to fourth images represent short-axis views and the fifth to eighth images represent horizontal long-axis view. The upper row shows resting myocardial perfusion imaging with SPECT Tc-99m sestamibi which reveals mildly decreased perfusion in the mid septal region. The second and third rows show myocardial inflammation imaging (FDG) before (second row) and after (third row) treatment with steroids. The second row demonstrates increased focal uptake of FDG in the area of inflammation, the mid and apical septal region. Repeat cardiac PET images after steroid therapy are shown in the third row. This shows that there is no longer any inflammation as demonstrated by the lack of uptake of FDG in the regions where this had been seen before, in the mid and apical septal regions
Figure 5
Extracardiac PET images. Images reveal no FDG uptake in hilar lymph nodes or in the chest. This would suggest no pulmonary sarcoidosis. The original Japanese Ministry of Health and Welfare Guidelines for Diagnosis of Cardiac Sarcoidosis published in 1993 were revised in 2006 and republished in 2007.2 By the revised guidelines, if this patient had histologic or clinical evidence of extracardiac sarcoid, he would meet criteria for a clinical diagnosis of cardiac sarcoid, as he has one major criterion (LVEF < 50%) and four of five minor criteria [VT, abnormal area of wall thickening on echo, a perfusion defect on a nuclear medicine scan (Tc-99m sestamibi), and delayed enhancement on MRI]. Due to the patchy nature of the disease process, however, yield of positive findings from biopsy remains low. This patient had abnormally elevated transaminases and a resultant liver biopsy that did not show any evidence of sarcoidosis. He also underwent mediastinal lymph node biopsy which did not show evidence of sarcoidosis. In a situation such as this, cardiac imaging studies can play an additional important and early role in providing supporting evidence for cardiac sarcoid, and thus allow for early initiation of therapy and prevention of morbidity and mortality. The initial mismatched defect in the septal region with cardiac PET (first and second rows of Figure 4), along with the delayed enhancement seen in the same region by cardiac MRI, is strongly suggestive of cardiac sarcoidosis. After treatment with anti-inflammatory agents, repeat cardiac PET demonstrated resolution of the regional inflammation
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