Clinical Diagnoses And Outcomes Of Patients Referred For Positron Emission Tomography Without Biopsy-Proven Sarcoidosis

Introduction

Cardiac sarcoidosis (CS) is in the differential diagnosis of cardiomyopathy (CMP), atrioventricular (AV) block, and/or ventricular tachycardia (VT). Fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) imaging is commonly used to facilitate diagnosis in suspected CS; however, the prognosis and final diagnosis of patients who undergo FDG PET/CT but do not have CS is unclear.

Aim

We aimed to study the clinical diagnoses and prognosis of patients referred for FDG PET/CT imaging who did not have biopsy evidence of sarcoidosis.

Methods

We retrospectively studied all consecutive patients clinically referred for FDG PET/CT at our center for suspected CS from June 2006 to November 2023. Patients with either biopsy-proven extracardiac sarcoidosis or CS and patients with FDG PET/CT evidence of extracardiac sarcoidosis were excluded. The remaining patients were further characterized according to final etiological diagnosis by subsequent testing. Incidence of the composite of ventricular assist device (VAD) placement, heart transplant, or all-cause death was examined in those with and without definitive CS.

Results

A total of 1,041 patients (mean age 57.9 ± 13.0; 30.1% female) met inclusion criteria: 46 ischemic CMP, 63 genetic CMP (pathogenic variant identified, hypertrophic CMP, arrhythmogenic right ventricular CMP, or familial dilated CMP), 187 inflammatory CMP, 242 other (such as AV block or VT with left ventricular ejection fraction ≥50%), and 503 non-ischemic CMP (A). 198 patients underwent genetic testing, of whom 31 patients (15.7%) were found to have a pathogenic variant in genes such as DSP, TTN, LMNA, and PKP2. Over a median follow up of 3.3 years, 180 patients met the primary outcome (23 VAD, 19 heart transplant, and 138 death) (B). Over 7.1 years of follow up, 25% of patients met the primary outcome.

Conclusions

Patients referred for FDG PET/CT without biopsy-proven sarcoidosis or imaging evidence of extracardiac disease are at risk for advanced heart failure in subsequent follow up. Many of these patients have genetic testing suggestive of arrhythmogenic CMP. These data highlight the importance of referral for genetic testing and advanced heart failure consultation in this population.