Application Of Multimodal MRI In Recovered COVID-19 Patients With Cardiac Injury

Part I Preliminary Application of Cardiac MRI in Recovered COVID-19 PatientsObjective: Coronavirus disease-2019(COVID-19)has been a global outbreak since March 2020.Myocardial injury caused by COVID-19 was previously reported in hospitalized patients.However,it is unknown if there is sustained cardiac involvement after patients’ recovery from COVID-19.The purpose of our study was to evaluate cardiac involvement in recovered COVID-19 patients who reported cardiac symptoms using cardiac magnetic resonance imaging(MRI).Methods: Twenty-six recovered COVID-19 patients that reported cardiac symptoms and underwent cardiac MRI exams and 20 healthy controls were retrospectively included.MRI protocols consisted of conventional sequences(cine,T2 WI,late gadolinium enhancement(LGE))and quantitative mapping sequences(T1 mapping,T2 mapping,and extracellular volume(ECV)).Myocardial edema ratio and focal fibrosis were semiquantitatively assessed in post-COVID-19 patients using T2 WI and LGE sequences.Cardiac morphology,function,native T1/T2,and ECV were quantitatively evaluated using cine and mapping sequences.Patients were further divided into two subgroups based on the presence or absence of positive conventional cardiac MRI findings,which were defined as increased myocardial edema ratio(> 2.0)and/or LGE presence.The MRI parameters were compared among recovered COVID-19 patients with positive conventional MRI findings,patients without positive findings,and healthy controls.Results: Fifteen patients(58%)had abnormal MRI findings on conventional MRI sequences: myocardial edema was found in 14(54%)patients and LGE was found in 8(31%)patients.Decreased right ventricular functional parameters including ejection fraction,cardiac index,and stroke volume index were found in patients with positive conventional MRI findings.Using quantitative mapping,global native T1,T2,and ECV were all found to be significantly elevated in patients with positive conventional MRI findings,compared to patients without positive findings and controls(P < 0.05).Conclusions: Cardiac involvement was found in a proportion of the recovered COVID-19 patients.Abnormal MRI manifestation mainly included myocardial edema,fibrosis,and impaired right ventricular function.Attention should be paid to the possible myocardial involvement in recovered COVID-19 patients with cardiac symptoms.Part II A 3-month Follow-up Study of Multimodal MRI in COVID-19-related Cardiac InjuryObjective: The sustained cardiac injury had been reported in recovered COVID-19 patients.However,there are no longitudinal MRI studies to access the dynamic evolution of COVID-19-related cardiac injury during the convalescent period.This study sought to evaluate the cardiac morphological,functional,and histological changes at a 3-month follow-up MRI by performing comprehensive longitudinal imaging in recovered COVID-19 patients with cardiac injury.Methods: Ten recovered COVID-19 patients diagnosed with myocardial inflammatory injury by MRI were prospectively enrolled in our study.Initial baseline MRI was performed 44 days(range,32-68 days)after the onset of cardiac symptoms and follow-up MRI after 3 months.Cardiac MRI included imaging of morphology and function,edema,and fibrosis using cine,semiquantitative T2 WI and LGE,and quantitative T1 mapping and T2 mapping.Results: Increased T2 WI signal intensity was observed in 9(90%)patients,and LGE lesions were presented in 6(60%)patients at baseline MRI.6(60%)patients had persistent increased T2 WI signal intensity,and 6(60%)had persistent LGE lesions at follow-up.1(10%)patient had a decreased left ventricular ejection fraction at baseline MRI,which did not improve significantly at follow-up.The remaining nine patients(90%)showed no adverse morphological and functional remodeling of the left ventricle at baseline and follow-up MRI.The global native T1 values and native T1 values of the lesion area were significantly decreased at follow-up MRI(P = 0.002 and P = 0.045,respectively).Conclusions: At a 3-month follow-up in the convalescent phase of cardiac injury,myocardial edema and fibrosis persisted in most COVID-19 patients,however,no newonset adverse left ventricular remodeling occurred.Cardiac MRI-T1 mapping is a sensitive tool for monitoring histological changes.And the mid-and long-term cardiac outcomes in patients with COVID-19 require further follow-up studies.Part III Assessment of The Mid-and Long-term Cardiac Injury in Recovered COVID-19 Patients by Multimodal MRIObjective: This study aimed to evaluate the mid-and long-term cardiac involvement in recovered COVID-19 patients by MRI;to investigate if there is cardiac dysfunction in recovered patients with preserved ejection fraction;to investigate the correlation between cardiac dysfunction and histological abnormalities in recovered COVID-19 patients.Methods: Sixty recovered COVID-19 patients with clinically suspected cardiac injury were prospectively enrolled.30 sex-and age-matched healthy control were also included.All patients underwent cardiac MRI 5-17 months after confirming acute infection with SARSCo V-2.Cardiac MRI was performed in all subjects,and the scan sequences included cine,T2 WI,LGE,and Mapping.Cardiac morphology and function were assessed using cine and MRI feature tracking(MRI-FT)techniques;myocardial edema and fibrosis were assessed by semi-quantitative T2 WI and LGE sequences,and diffuse myocardial injury was quantitatively assessed by native T1 and T2 mapping.Patients were further divided into EFreduced subgroups and EF-preserved subgroups based on the presence or absence of impaired left or right ventricular ejection fraction(EF).The MRI parameters were compared among the patients with reduced EF,the patients with preserved EF,and the healthy controls.Results: A total of 12 patients had reduced EF and 48 patients had preserved EF.There were significant differences of left and right ventricular ejection fraction,end-systolic volume,end-systolic volume index,stroke volume index and right ventricular stroke volume,cardiac output,cardiac index among the three groups(P < 0.05).The left ventricular global longitudinal,radial,and circumferential peak strain and strain rate and right ventricular global radial and circumferential peak strain and global radial peak strain rate were significantly decreased in patients with reduced EF,compared to healthy controls(P < 0.05).And the left ventricular global longitudinal peak strain and strain rate,circumferential peak strain rate,and right ventricular global radial and circumferential peak strain and radial peak strain rate were also significantly decreased in patients with preserved EF(P < 0.05).Six(50%)patients with reduced EF and 16(33%)patients with preserved EF showed increased global or focal T2 WI signal intensity.Eight(67%)patients with reduced EF and 19 patients(40%)with preserved EF presented with LGE lesions.Compared to healthy controls,the myocardial T1 values of segment 10 and the myocardial T2 values of segment 12 in the patients with reduced EF were significantly increased(P < 0.05),and the myocardial T1 values of segment 15 in the patients with preserved EF were also significantly increased(P < 0.05).Left ventricular ejection fractions in patients with reduced EF were negatively correlated with global T1(r =-0.82,P = 0.001)and T1(max)values(r =-0.71,P = 0.01).Conclusions: MRI showed that patients who recovered from COVID-19 still had mid-and long-term cardiac damage,mainly including biventricular dysfunction(reduced EF and strain parameters)and residual histological abnormalities(edema and focal fibrosis).Left ventricular systolic dysfunction may be associated with myocardial fibrosis.Cardiac MRIFT technology is a sensitive tool to detect biventricular dysfunction in patients with preserved EF.