1Universitätsklinikum Tübingen Innere Medizin III, Kardiologie und Angiologie Tübingen, Deutschland; 2Universitätsklinikum Tübingen Diagnostische und Interventionelle Radiologie Tübingen, Deutschland; 3Universitätsklinikum Tübingen Nuklearmedizin Tübingen, Deutschland
Objective
To examine the diagnostic value of combined hybrid cardiac magnetic resonance (CMR) and 18F-Fluorodeoxyglucose positron emission tomography (FDG-PET) for detection and separation of active vs. healed myocardial injury in patients with a history of confirmed SARS-CoV-2 infection and persistent symptoms (>3 months) which cannot be explained by an alternative diagnosis (= long COVID).
Background
Late gadolinium enhancement (LGE)-CMR and FDG-PET are both established imaging techniques for the detection of myocardial injury in inflammatory cardiomyopathies. Although some CMR data suggest a high prevalence of myocardial injury in acute COVID, there is limited data regarding the value of a combined hybrid CMR/FDG-PET imaging approach in patients with persistent symptoms after COVID.
Methods
Twenty-two patients with persistent symptoms from the onset of COVID (median symptom duration 7.5 months, age 38 ± 12 years; 55% female) were prospectively enrolled for evaluation of suspected myocardial injury. Fatigue (76%) and palpitations (71%) were the most common symptoms, followed by chest pain (61%) and dyspnea (53%). ECG was abnormal in 5 patients (23%). No patient had a history of coronary artery disease. After dietary preparation for suppression of myocardial glucose metabolism, patients were evaluated on a 3 Tesla hybrid PET/MR scanner. CMR protocol included T1 and T2 mapping, myocardial function and LGE imaging. We assumed active myocardial injury, if PET and CMR (i.e. LGE or T1/T2 mapping) were both positive (PET+ CMR+), healed myocardial injury if PET was negative but CMR (i.e. LGE or T1 mapping) was positive (PET- CMR+), no myocardial injury if patients were CMR negative irrespective of PET findings.
Results
Combined CMR/FDG-PET revealed a preserved left ventricular ejection fraction (66 ± 5%). Active myocardial injury was diagnosed in 8 (36%) patients, healed myocardial injury in 6 (28%) patients, and no myocardial injury in 8 (36%) patients. Non-ischemic LGE was present in 6 (27%) patients; T1 mapping was increased in 12 (55%) patients, T2 mapping was increased in 12 (55%) patients; PET showed focal uptake in 8 (36%) patients.
Conclusions
A combined CMR/FDG-PET imaging approach is useful not only for the detection of myocardial injury, but also for the separation of active myocardial injury from healed myocardial injury, which might have further implications for the monitoring and treatment of patients with long COVID.