Abnormal Left Atrial Strain by CMR is Associated with Left Heart Disease in Patients with Pulmonary Hypertension

Background: Pulmonary hypertension (PH) is classified as pre-capillary, isolated postcapillary (IpcPH), combined post- and pre-capillary (CpcPH), or exercise PH. IpcPH associated with left heart disease can lead to pulmonary vascular remodeling and eventually CpcPH. Conversely, pre-capillary PH may be diagnosed in the presence of cardiovascular comorbidities including left heart disease. Atrial functional impairment is a frequent finding in cardio-pulmonary disease reflecting both intrinsic atrial cardiomyopathy and congestion. Consequently, we sought to investigate this across the PH spectrum. Methods: Patients referred to both right heart catheterization (RHC) and cardiovascular magnetic resonance (CMR) imaging were enrolled in this monocentric registry. Patients were classified by RHC according to current guideline recommendations. CMR assessment included left/right ventricular (LV/RV) and atrial (LA/RA) volumes and deformation imaging. Results: The study population consisted of n=209 patients (n=55 normal, n=72 pre-capillary, n=27 CpcPH, n=15 IpcPH, n=34 exercise and n=6 unclassified PH). N=126 patients underwent additional exercise-stress RHC. Median LA total strain (Es) was lowest and similar in IpcPH (10.0%) and CpcPH (10.0%) which were significantly impaired compared to normal hemodynamics (30.8%, both p<0.001), pre-capillary (28.2%, both p<0.001) and exercise PH (26.9%, IpcPH: p=0.039, CpcPH: p=0.048). LA Es and LV global longitudinal strain (GLS) showed good diagnostic performance to identify patients with left cardiac involvement evident at rest (pulmonary capillary wedge pressure (PCWP) ≥15mmHg) (AUC 0.81 vs 0.77, p=0.20) whilst LA Es emerged superior for identification of exercise-stress induced PCWP ≥25mmHg (AUC 0.79 vs 0.70, p=0.039). Conclusions: LA functional impairment is a sign of left heart involvement in PH patients. LA Es emerged superior for identification of left heart disease unmasked during exercise-stress compared to GLS. Consequently, LA strain may become an innovative method to detect early stage left heart disease in PH.