Different associations between left atrial size and 2.5-year clinical outcomes in patients with anterior versus non-anterior wall ST-elevation myocardial infarction

Abstract

Objective: To investigate associations between left atrial diameter (LAD) and long-term outcomes in patients with anterior or non-anterior wall ST-elevation myocardial infarction (STEMI).

Methods: Patients with STEMI were included in this secondary analysis of data from a prospective cohort study in which the primary outcome was major adverse cardiovascular event (MACE) occurrence during a 2.5-year follow-up. A LAD cut-off value was obtained through receiver operating characteristic curve analysis. Kaplan-Meier curve and Cox regression analyses were applied. Subgroup Cox regression analysis was also performed, with patients stratified based on left ventricular diastolic diameter (LVEDD, > 55 mm and ≤55 mm). The relationship between LAD and outcomes in patients with anterior or non-anterior wall STEMI was explored using restricted cubic spline functions.

Results: Out of 464 patients, adjusted Cox regression showed that dichotomous (>40 mm) LAD was significantly associated with MACE (hazard ratio 2.978, 95% confidence interval 1.763, 5.030) in patients with anterior wall but not non-anterior wall STEMI. The association was not different between normal and enlarged LVEDD groups.

Conclusions: A left atrium > 40 mm may indicate higher risk of MACE in patients with anterior wall STEMI, even in patients with normal left ventricular structure. This relationship was not observed in patients with non-anterior wall STEMI.

Keywords: Left atrial size; anterior wall myocardial infarction; echocardiography.

Figure 1.

Kaplan-Meier curves of MACE incidence during 2.5-years of follow-up in patients with (a) anterior wall STEMI or (b) non-anterior wall STEMI, categorized according to LAD. MACE, major adverse cardiovascular event; LAD, left atrial diameter; STEMI, ST-elevation myocardial infarction.

Figure 2.

Multivariable Cox regression models with restricted cubic splines, showing adjusted HRs for MACE according to LAD in patients with anterior wall STEMI. MACE, major adverse cardiovascular event; HR, hazard ratio; LAD, left atrial diameter; STEMI, ST-elevation myocardial infarction; CL, confidence limit.

Figure 3.

Multivariable Cox regression models with restricted cubic splines, showing adjusted HRs for MACE according to LAD in patients with non-anterior wall STEMI. MACE, major adverse cardiovascular event; HR, hazard ratio; LAD, left atrial diameter; STEMI, ST-elevation myocardial infarction; CL, confidence limit.

Figure 4.

Prognostic effect of LAD on MACE during a 2.5-year follow-up in patients with either (a) anterior wall STEMI and LVEDD > 55 mm, (b) anterior wall STEMI and LVEDD ≤ 55 mm, (c) non-anterior wall STEMI and LVEDD > 55 mm, or (d) non-anterior wall STEMI and LEVDD ≤ 55 mm. MACE, major adverse cardiovascular event; LAD, left atrial diameter; STEMI, ST-elevation myocardial infarction; LVEDD, left ventricular diastolic diameter.