Left Atrial Volume Index as Predictor of Events in Acute Coronary Syndrome

Abstract

Dear Editor, The Left Atrial Volume Index (LAVi) is a measurement that has gained importance in daily clinical practice due to evidence of its capacity to predict mortality, in patients followed after an Acute Myocardial Infarction (AMI), as well as in the general population1. The study by Secundo Junior et al. sought to evaluate the role of LAVi as a predictor of late events in patients with acute coronary syndrome2. This study was able to corroborate previous findings in patients with AMI and demonstrated that increased LAVi may also be able to predict major cardiovascular events in patients with unstable angina. Correspondingly, it showed that patients with increased LAVi were those with higher prevalence of systemic arterial hypertension (SAH), previous AMI and angioplasty, of older age, with higher body mass index (BMI), lower left ventricular (LV) ejection fraction and more severe diastolic dysfunction, showing that the index may be a marker related to a higher occurrence of cardiovascular diseases and comorbidities. In cohort studies, a significant problem is the presence of non-controlled variables, which are potential confounding factors that can possibly interfere with the results. The degree of reperfusion success (assessed by TIMI flow, myocardial blush or ST-segment recovery), which maintains significant correlation with better survival, can be one of those factors not measured in this study3. Another confounding factor could be the incidence of atrial fibrillation (AF) in the extra-hospital period. The causal association between AF and ischemic cerebrovascular accident (CVA) has been documented, regardless of echocardiographic findings. It is associated with a four to five-fold increase in the risk of ischemic CVA4 and it is responsible for more than 15% of these events in individuals in all age ranges and 30% in individuals older than 80 years5. Thus, it is not clear, in the results of Secundo Junior et al., whether the high incidence of CVA in the non-hospital follow-up was due only to the increase in LAVi or the possible occurrence of this arrhythmia, and one cannot say that there was no influence of better or worse reperfusion on the incidence of events in either group.