Looking at the best indexing method of left atrial volume in the hypertensive setting

Abstract

Systemic hypertension adversely impacts cardiac structure and function, causing a wide spectrum of alterations, such as myocyte hypertrophy and interstitial fibrosis leading to left ventricular (LV) concentric remodeling, increased LV mass, and systolic and diastolic dysfunction. Furthermore, an impressive amount of evidence suggests that left atrial enlargement (LAE), identified by assessing the diameter, or more accurately, the volume with transthoracic echocardiography, is a reliable index of a sustained increase in LV filling pressure in the hypertensive setting [1]. LA acts as a volume sensor of the heart, and its dilatation reflects altered dynamics of ventricular relaxation and filling. The close association between LA volume (LAV) and LV diastolic dysfunction has resulted in LAV becoming one of the key diagnostic criteria for LV diastolic dysfunction [2]. LAE is regarded as a strong risk marker for the future development of atrial fibrillation and a robust, independent predictor of heart failure hospitalizations, stroke, and allcause death. The mechanism accounting for the association between LAE and cardiovascular events is multifactorial and may be attributed to underlying pathologies causing LA morphofunctional alterations and elevated LV filling pressure and to arrhythmias (i.e., atrial fibrillation), often a consequence of LAE. The unfavorable prognostic significance of LAE has been further confirmed and expanded in recent years by new evidence based on novel echocardiographic techniques (i.e., twoor three-dimensional speckle tracking echocardiography) and magnetic resonance imaging. LAE measured by fourand two-chamber cine cardiac magnetic resonance imaging demonstrated a strong independent association with all-cause mortality in a very large, heterogeneous cohort totaling 10890 patients [3]. Over a median follow-up period of 49 months, mild, moderate, and severe LAE was a significant predictor of death. After adjustment for clinically relevant covariates, moderate (HR= 1.45, 95% CI: 1.1–1.89) and severe (HR= 1.64, 95% CI: 1.29–2.08) but not mild LAE remained independent predictors of all-cause mortality. Identification of abnormal cardiac phenotypes (i.e., LV hypertrophy and LAE) by echocardiography has a pivotal role in cardiovascular risk stratification and subsequent therapeutic decision making. Methodological aspects related to this technique may affect the precision of cardiac assessment and the correct classification of patients according to subclinical organ damage. Indeed, the accuracy and precision of quantitative echocardiography are related to multiple factors, including operator experience, patient echogenic characteristics, equipment technology, reliable reading protocols, and appropriate methods for normalizing cardiac parameters for the different body sizes of patients based on precise collection of anthropometric variables. For this latter aspect, it has been reported that indexing echocardiographic parameters to self-reported rather than measured anthropometric values may impair the capacity of detecting LAE. The findings of a multicenter Italian survey showed that misreporting weight and height by individuals attending outpatient echocardiographic laboratories resulted in an underestimation of the prevalence of LAE by 4% and that misclassification was greater among elderly individuals than among young and middle-aged adults [4]. The value of LAV varies according to sex, age, body size, and ethnicity. The indexing of LAV allows comparison among individuals with different body sizes; however, the best method of normalization for body size remains open to debate. The American Society of Echocardiography * Cesare Cuspidi [email protected]