Cardiac Magnetic Resonance Left Atrial Myocardial Strain Technique For Normal Population And Patients With Hypertrophic Cardiomyopathy: A Pilot Study

Part 1Preliminary study of cardiac magnetic resonance feature tracking derived left atrial strain and strain rate parameters in healthy Chinese adultsObjective:The aim of this study was to assess sex-and age-specific normal values of left atrium(LA)myocardial strain and strain rate(SR)in healthy adults in China by cardiac magnetic resonance(CMR).Materials and methods:110 healthy adults(45.65±12.77,76 males)were retrospectively included,all of whom underwent 3.0T CMR and were stratified according to gender and age.LA global longitudinal strain(GLS),GLS SR,and global circumferential strain(GCS)were assessed using CMR.The GLS is divided into three stages: reservoir,conduit and booster.Results:LA GLS reservoir,GLS conduit,GCS and SR reservoir were significantly greater in females compared to males(P <0.05).Differences in LA GLS reservoir,SR reservoir and GLS conduit and SR conduit between age groups were statistically significant(all P <0.05)and gradually decreased with increasing age.Among females,age was significantly negatively correlated with LA GLS conduit,SR conduit(P <0.001),significantly positively correlated with GLS booster(P =0.034)and not significantly correlated with GLS reservoir(P =0.070).In the male population,a significant negative correlation(P≤0.001)could be found between age and both LA GLS(reservoir,conduit)and SR(reservoir,conduit).Conclusions:MR is feasible and reproducible for quantifying LA strain and SR and determining left atrial phase function.The presence of age-and sex-related differences in LA strain and SR suggests the need to establish specific normal values for individual groups.Part 2Predictive value of left atrial strain analysis in adverse clinical events in patients with hypertrophic cardiomyopathy: a CMR studyObjective:A subset of patients with hypertrophic cardiomyopathy(HCM)will experience adverse clinical events such as heart failure(HF),cardiovascular death,and new-onset atrial fibrillation(AF).Current risk stratification methods are imperfect and limit the identification of patients at high risk for HCM.This study aimed to evaluate the role of cardiac magnetic resonance(CMR)-derived left atrial strain parameters in the occurrence of adverse clinical events in patients with HCM.Materials and methods:Left atrial(LA)structural,functional,and strain parameters were evaluated in 99 patients with HCM and compared with 89 age-,sex-,and BMI-matched control subjects.LA strain parameters were derived from CMR two-and four-chamber cine images by a semiautomatic method.LA strain parameters include global longitudinal strain(GLS)and global circumferential strain(GCS).The LA GLS includes reservoir strain(GLS reservoir),conduit strain(GLS conduit),and booster strain(GLS booster).Three LA GLS strain rate(SR)parameters were derived: SR reservoir,SR conduit,and SR booster.The primary endpoint was set as a composite of adverse clinical events,including SCD,newonset or worsening to hospitalized HF,new-onset AF,thromboembolic events,and fatal ventricular arrhythmias.Results:LA GLS,GLS SR and GCS were impaired in HCM patients compared to control subjects(all p < 0.001).After a mean follow-up of 37.94 ± 23.69 months,18 HCM patients reached the primary endpoint.LA GLS,GLS SR,and GCS were significantly lower in HCM patients with adverse clinical events than in those without adverse clinical events(all p < 0.05).In stepwise multiple Cox regression analysis,LV SV,LA diameter,pre-contraction LAV(LAV pre-ac),passive LA ejection fraction(EF),and LA GLS booster were all independent determinants of adverse clinical events.LA GLS booster ≤8.9% was the strongest determinant(HR=8.9 [95%CI(1.951,40.933)],P =0.005).Finally,LA GLS booster provided predictive adverse clinical events value(AUC=0.86 [95%CI0.77-0.98])that exceeded traditional outcome predictors.Conclusions:LA strain assessment,a measure of LA function,provides additional predictive information for established predictors of HCM patients.LA GLS booster was independently associated with adverse clinical events in patients with HCM.