Abstract
1575
Background: Sarcoidosis is a multisystem disease of unknown etiology. The prevalence of clinically evident cardiac involvement is about 5%, though this may be an underestimation given the difficulties of diagnosing cardiac sarcoidosis (CS). Only 40% of patients with CS diagnosed at autopsy have the diagnosis made during their lifetime. Cardiac PET is an excellent tool for diagnosis and follow up of CS patients. Little is known of the regional myocardial involvement of CS. In the current series, we utilize PET to determine the most commonly sarcoid-afflicted myocardium regions.
Methods: 45 patients (mean age 54 +/- 8.4, 69% male) had studies positive for CS with N-13 NH3/FDG PET/CT (N=99 total scans). Patients adhered to a standardized protocol, undergoing a 24 hour fast from carbohydrates, plus unfractionated heparin intravenously (10-50IU/kg) 15 minutes prior to FDG injection. Scans were obtained 90 minutes after FDG injection. All patients underwent rest N-13 NH3 perfusion imaging prior to administering FDG. Perfusion-metabolism mismatch defects and mean SUV for involved segments in the 17 segment model were determined using INVIA 4DM software. Presence of sarcoid was determined using the perfusion-metabolism mismatch defect criteria. Percentage of cardiac sarcoidosis was calculated per segment (1-17 individually), and per segment group [basal region (segments 1-6), middle region (segments 7-12), and distal region (segments 13-17)]. Results: Of the sarcoid-positive scans, 88% contained sarcoid in the basal region, which was significantly higher (p<0.0001) than the 38% in the middle region and the 10% in the distal region. There was no significant difference between the middle and distal regions (p=0.09). Segment 1 (basal anterior) had a significantly higher (p<0.0001) prevalence than all other segments in the basal region except segment 2. Segment 2 (basal anteroseptal) had a significantly higher (p<0.0001) prevalence than segments 3 and 4, but not segments 5 and 6 (p=0.0005). Conclusion: This study shows a significant amount of cardiac sarcoidosis occurring in the basal region of the myocardium, specifically in the basal anterior and basal anteroseptal segments. This is valuable because most patients with CS present with complete heart block or ventricular arrhythmias, which originate from the basal anterior and basal septal regions. Understanding the regional distribution of CS may lead to better-informed prevention of these debilitating cardiac events.