Left atrial active contractile function parameters assessed by cardiac MR are sensitive to myocardial iron

PURPOSE: To determine the impact of myocardial iron overload on left atrial (LA) volume and function using MR in patients with systemic iron overload.

MATERIALS AND METHODS: Thirty-eight patients with systemic iron overload disease and 10 controls underwent 1.5 Tesla MR performing steady state free precession short-axis cine-series of the LA. Three-dimensional-volumetry was assessed to calculate LA volumes and function. Parameters were indexed (i) to body surface area. The myocardial transverse relaxation rate R2* was determined in the ventricular septum using a multi-echo GRE sequence (breathhold; electrocardiography triggered; 12 echoes; echo time = 1.3-25.7 ms).

RESULTS: Significantly decreased active atrial emptying fraction (AAEF) (23% [95%-range, 7-34] versus 36% [95%-range, 14-49], P = 0.009), active atrial emptying volume (AAEVi) (5.5 mL/m(2) [95%-range, 2-11] versus 11.9 mL/m(2) [95%-range, 3-23], P = 0.008), and active peak emptying rate (APERi) (46 mL/s/m(2) [95%-range, 29-69] versus 75 mL/s/m(2) [95%-range, 45-178], P < 0.001) were found for patients with myocardial iron overload (R2* > 40 s(-1) ) compared with patients with normal myocardial iron levels (R2* < 40 s(-1) ). Receiver operating characteristics (ROC) analysis revealed higher potential to indicate myocardial iron overload for the AAEF (area under the ROC curve [AUC] = 0.84; P < 0.0001), APERi (AUC = 0.87; P < 0.0001), and AAEVi (AUC = 0.80; P < 0.0001) compared with LA ejection fraction (LAEF) (AUC = 0.68; P = 0.02) with equal sensitivities and specificities of 82% (AAEF), 79% (APERi), 73% (AAEVi), and 57% (LAEF).

CONCLUSION: MR parameters of active LA contractile function were associated with myocardial iron overload. This cross-sectional study suggests impaired active LA contractile function to be sensitive to myocardial iron toxicity. J. Magn. Reson. Imaging 2016.