Left Atrial Minimum Volume Index at Cardiac MRI Predicts Adverse Outcomes after Acute Myocardial Infarction

Background Left atrial (LA) structural and functional parameters are associated with prognosis after acute myocardial infarction (AMI). Purpose To explore the prognostic value of LA minimum volume index (LAVImin) as measured at cardiac MRI and its incremental predictive value beyond LA functional parameters for predicting major adverse cardiovascular events (MACE) after AMI in a large population. Materials and Methods This prospective study enrolled patients with AMI who underwent percutaneous coronary intervention and subsequent cardiac MRI between February 2014 and January 2024. MACE included all-cause death, reinfarction, unplanned revascularization, and heart failure hospitalization. Univariable and multivariable Cox regression analyses were used to evaluate the association between LAVImin and MACE. Receiver operating characteristic analysis and Kaplan-Meier analysis were used to evaluate the prognostic value of LAVImin in participants with AMI. Results A total of 1191 participants (mean age, 58 years ± 11 [SD]; 1007 male participants) were included. Among them, 183 individuals experienced MACE over a median follow-up of 38 months (IQR, 20-57 months). After adjusting for clinical risk factors and cardiac MRI parameters, a larger LAVImin was independently associated with MACE (hazard ratio, 1.06 [95% CI: 1.05, 1.08]; P < .001). Receiver operating characteristic analysis revealed that LAVImin (area under the receiver operating characteristic curve [AUC], 0.74) had better discriminative ability for MACE than LA maximum volume index (LAVImax) (AUC, 0.65; P < .001) and LA conduit strain (AUC, 0.64; P < .001). Traditional risk predictors plus LAVImin had greater prognostic value for MACE (C index, 0.75) than traditional risk factors alone (C index, 0.69; P < .001) or traditional risk predictors plus LAVImax (C index, 0.72; P = .03). Conclusion LAVImin was an independent predictor of MACE after AMI, with incremental prognostic value and improved discriminative ability over traditional risk factors including cardiac MRI parameters.