Incidence of abnormal positron emission tomography in patients with unexplained cardiomyopathy and ventricular arrhythmias: The potential role of occult inflammation in arrhythmogenesis.
BACKGROUND
The incidence of myocardial inflammation in patients with unexplained cardiomyopathy referred for ventricular arrhythmias (VAs) is unknown.


OBJECTIVE
The purpose of this study was to report fasting positron emission tomographic (PET) scan findings in consecutive patients referred with unexplained cardiomyopathy and VA.


METHODS
Fluorine-18 fluoro-2-deoxyglucose (18-FDG) PET/computed tomographic (CT) scans with a >16-hour fasting protocol were prospectively ordered for patients referred for VA and unexplained cardiomyopathy (ejection fraction <55%). Patients with focal myocardial FDG uptake were labeled as arrhythmogenic inflammatory cardiomyopathy (AIC) and classified into 4 groups based on the presence of lymph node uptake (AIC+) and perfusion abnormalities (early vs late stage).


RESULTS
Over a 3-year period, 103 PET scans were performed, with 49% (AIC+ 17, AIC 33) exhibiting focal FDG uptake. Mean patient age was 52 ± 12 years (ejection fraction 36% ± 16%). Patients with AIC were more likely to have a history of pacemaker (32% vs 6%, P = .002) compared to those with normal PET. When biopsy was performed, histologic diagnosis revealed nongranulomatous inflammation in 6 patients and sarcoidosis in 18 patients. Ninety percent of patients with AIC/AIC+ were prescribed immunosuppressive therapy, and 58% underwent ablation. Correlation between low voltage regions on electroanatomic mapping and FDG uptake was observed in 74%. Magnetic resonance imaging findings matched abnormal PET regions in only 40%.


CONCLUSIONS
Nearly 50% of patients referred with unexplained cardiomyopathy and VA demonstrate ongoing focal myocardial inflammation on FDG PET. These data suggest that a significant proportion of patients labeled "idiopathic" may have occult AIC, which may benefit from early detection and immunosuppressive medical therapy.
UCLA Cardiac Arrhythmia Center, UCLA Health System, Los Angeles, California.
Roderick
R
Tung
UCLA Cardiac Arrhythmia Center, UCLA Health System, Los Angeles, California.
Brenton
B
Bauer
UCLA Department of Nuclear Medicine, Department of Molecular and Medical Pharmacology, Los Angeles, California.
Heinrich
H
Schelbert
UCLA Department of Medicine, Division of Pulmonary, and Critical Care Medicine, Los Angeles, California.
Joseph P
JP
Lynch
UCLA Department of Nuclear Medicine, Department of Molecular and Medical Pharmacology, Los Angeles, California.
Martin
M
Auerbach
UCLA Department of Nuclear Medicine, Department of Molecular and Medical Pharmacology, Los Angeles, California.
Pawan
P
Gupta
UCLA Department of Nuclear Medicine, Department of Molecular and Medical Pharmacology, Los Angeles, California.
Christiaan
C
Schiepers
UCLA Cardiac Arrhythmia Center, UCLA Health System, Los Angeles, California.
Samantha
S
Chan
UCLA Cardiac Arrhythmia Center, UCLA Health System, Los Angeles, California.
Julie
J
Ferris
UCLA Department of Nuclear Medicine, Department of Molecular and Medical Pharmacology, Los Angeles, California.
Martin
M
Barrio
UCLA Department of Nuclear Medicine, Department of Molecular and Medical Pharmacology, Los Angeles, California.
Olujimi
O
Ajijola
UCLA Cardiac Arrhythmia Center, UCLA Health System, Los Angeles, California.
Jason
J
Bradfield
UCLA Cardiac Arrhythmia Center, UCLA Health System, Los Angeles, California; UCLA Department of Medicine, Division of Pulmonary, and Critical Care Medicine, Los Angeles, California. Electronic address: kshivkumar@mednet.ucla.edu.
Kalyanam
K
Shivkumar
D000328:Adult; D000368:Aged; D001145:Arrhythmias, Cardiac / Q000175:diagnosis / Q000209:etiology* / Q000628:therapy; D009202:Cardiomyopathies / Q000000981:diagnostic imaging* / Q000209:etiology / Q000628:therapy; D015331:Cohort Studies; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D015994:Incidence; D007249:Inflammation / Q000150:complications* / Q000175:diagnosis / Q000453:epidemiology*; D008198:Lymph Nodes; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D009205:Myocarditis / Q000000981:diagnostic imaging; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D012017:Referral and Consultation; D014057:Tomography, X-Ray Computed
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
Cardiomyopathy; Inflammation; Positron emission tomography; Ventricular arrhythmia