Left atrial mechanics in patients with acute STEMI and secondary mitral regurgitation: A prospective pilot CMR...

Left atrium (LA) is an important biomarker of adverse cardiovascular outcomes and cerebrovascular events. This study aimed to evaluate LA myocardial deformation using cardiac magnetic resonance feature tracking (CMR-FT) in patients with acute ST-segment elevation myocardial infarction (STEMI) and secondary mitral regurgitation (MR). Additionally, to assess interobserver and intraobserver variability of the technique.

Twenty patients with STEMI underwent CMR with a 1.5Tesla MRI scanner. According to the presence of MR patients were divided into two groups: MR(+) and MR(-). Total LA strain (ɛ_s), passive LA strain (ɛ_e), and active LA strain (ɛ_a) were obtained. Additionally, total, passive and active strain rates (SR_s, SR_e, and SR_a) were calculated. To assess interobserver agreement data analysis was performed by second independent observer.

LA volumetric and functional parameters were similar in both groups. All LA strain values were significantly higher in patients with MR: ɛ_s (27.67±10.25 for MR(-) vs. 32.80±6.95 for MR(+); P=0.01), ɛ_e (15.29±7.30 for MR(-) vs. 19.22±6.04 for MR(+); P=0.01) and ɛ_a (12.38±4.23 for MR(-) vs. 14.44±5.19 for MR(+); P=0.03). Only SR_e significantly increased in patients with MR (-0.57±0.24 for MR(-) vs. -0.70±0.20 for MR(+); P=0.01). All LA deformation parameters demonstrated high interobserver and intraobserver agreement.

Conventional volumetric and functional LA parameters do not detect early changes in LA performance in patients with STEMI and secondary MR. In contrast, LA reservoir, passive and active strain are significantly higher in patients with MR. Only peak early negative strain rate substantially increases during secondary MR. LA deformation parameters derived from conventional cine images using CMR-FT technique are highly reproducible.