Left Atrial Strain Impairment Precedes Geometric Remodeling as a Marker of Post-Myocardial Infarction Diastolic Dysfunction.

ABSTRACT

OBJECTIVES: The aims of this study were to test the magnitude of agreement between echocardiography (echo)- and cardiac magnetic resonance (CMR)-derived left atrial (LA) strain and to study their relative diagnostic performance in discriminating diastolic dysfunction (DD) and predicting atrial fibrillation (AF). BACKGROUNDS Peak atrial longitudinal strain (PALS) is a novel performance index. Utility of echo-quantified LA strain has yet to be prospectively tested in relation to current DD guidelines or compared to CMR. METHODS: The study population comprised 257 post-myocardial infarction (MI) patients undergoing echo and CMR, including prospective derivation (n = 157) and clinical validation (n = 100) cohorts. DD was graded on echo using established consensus guidelines blinded to strain results. RESULTS: PALS on both echo and CMR was nearly 2-fold lower among patients with versus no DD (p < 0.001) and was significantly different in those with mild versus no DD (p < 0.01). In contrast, LA geometric parameters including echo- and CMR-derived volumes were significantly different between advanced versus no DD groups (p < 0.001) but not between groups with mild versus no DD (all p > 0.05). Echo and CMR PALS yielded small differences irrespective of orientation and similar diagnostic performance for DD in the derivation (area under the curve [AUC] 0.70 to 0.78) and validation (AUC 0.75 to 0.78) cohorts. Impaired PALS on both modalities was independently associated with MI size (p < 0.001). During 4.4 ± 3.8 years of follow-up in the derivation cohort, 8% developed AF. Both 2-chamber echo- and CMR-derived PALS stratified arrhythmic risk (p = 0.004 and p = 0.02, respectively), including a 4-fold difference among patients in the lowest versus remainder of quartiles of echo-derived PALS (24% vs. 6%). Similarly, echo and CMR PALS were lower (both p < 0.05) among patients with subsequent heart failure hospitalizations. CONCLUSIONS: Echo-derived PALS parallels results of CMR, yields incremental diagnostic utility versus LA geometry for stratifying presence and severity of DD, and improves prediction of AF and congestive heart failure after MI.