Commentary on: ‘Cuspidi C., et al. Left ventricular systolic dysfunction in obesity: a meta-analysis of speckle tracking echocardiographic studies’

The main aim of the study by Cuspidi et al. [1], published in the present issue of the Journal of Hypertension, was to provide the results of a meta-analysis of studies that evaluated cardiac function in obese patients by speckle tracking echocardiography; the authors' main conclusion was that calculation of left ventricular (LV) global longitudinal strain (GLS) may identify early/limited/subtle LV systolic dysfunction that the calculation of LV ejection fraction by standard echocardiography was unable to identify [1]. There are few doubts that strain-based imaging techniques (and specifically speckle-tracking echocardiography) have been shown to possess clinical utility in a variety of settings [2]. In particular, three-dimensional (3D) speckle tracking echocardiography may be regarded as an advanced imaging technique designed for LV myocardial deformation analysis based on 3D data sets [3]. 3D speckle tracking echocardiography has the potential to overcome some of the intrinsic limitations of two-dimensional speckle tracking echocardiography [3]. The present study did not consider separately the two approaches, probably due to the relative low number of studies using 3D speckle tracing echocardiography in obesity, being a relatively younger technique still undergoing technological developments [3]. Assessment of LV systolic function by GLS from speckle tracking echocardiography may be considered, in any case, a sensitive and feasible method that overcomes many of the limitations of LV ejection fraction [4], including reproducibility issues of serial testing and detection of LV dysfunction in pathologically remodeled hearts [4]. Although some doubts were raised about the clinical role of obesity as an independent cardiovascular risk factor, thus leading to hypothesize an 'obesity paradox', because of the observation of paradoxically better outcomes in older obese patients [5], even in those with chronic heart failure [6], there is general agreement about the fact that obesity condition causes morphological and functional alterations involving the cardiovascular system, including left ventricular remodeling and epicardial fat accumulation, endothelial dysfunction and coronary microvascular dysfunction [7]. These can represent the substrates for different cardiovascular diseases, such as atrial fibrillation, coronary artery disease, sudden cardiac death, and heart failure with both preserved ejection fraction and reduced ejection fraction [7]. Notably, Cuspidi et al.[1] affirm that their data suggest that calculation of GLS should be incorporated into routine work-up aimed to identify obesity-mediated subclinical cardiac damage [1]. Although multiimaging modalities are required for appropriate recognition of subclinical systolic dysfunction typically associated with obesity, standard echocardiography remains, at least in my opinion, the most cost-effective technique [7]. In human hypertension, a very prevalent phenotype, such as left ventricular hypertrophy, present despite therapeutic interventions in nearly two-third of hypertensive at least in some surveys [8], is rarely assessed in real-life situations [9]. In fact, data again from Cuspidi et al., indicate that, in hypertensive patients undergoing a standard echocardiographic assessment, absolute LV mass, LV mass index and relative wall thickness were calculated only in 45.5, 24.6 and 12.3% of the cases, respectively. Parameters of LV diastolic filling were measured in two-thirds of the cases and estimation of E/A ratio was provided by less than 20% of the examinations [9]. This study, although performed in 2008, shows, therefore, that a large majority of echocardiographic examinations routinely performed in hypertensive patients in order to detect cardiac damage do not report qualifying data on LV mass, LV geometry and diastolic function [9]. These results indicate that a quantitative assessment of LV morphology and function is rarely provided in clinical practice. It is, therefore, probable that such difficulties are present also in obesity, a condition which is, moreover, perceived as less risky than hypertension by the general population; in addition, echocardiography may have serious limitations in obese subjects owing to poor acoustic window and attenuation artifacts. In general, excess adiposity may be challenging for cardiac imaging interpretation and diagnostic accuracy [10]. If it seems so difficult to obtain useful information and data from a standard echocardiography, which is widely available and relatively easy to perform, the suggestion of performing a speckle tracking echocardiographic assessment (a more complex and less commonly available approach) in the majority of obese patients could actually prove inapplicable in the real world and might be regarded as a 'flight of Icarus'. In conclusion, although the appropriate choice of tests depends on the knowledge of methods and their limitations, patient management in obesity should be tailored according to clinical evaluation and technique availability [10].