obesity is a major public health problem , with a prevalence of 10% to 20% in western europe .
obesity is characterized by both a large increase in body weight and an increase in body fat exceeding standard measures . currently , obesity is classified on the basis of body mass index ( bmi ) , and patients with bmi > 30  kg / m are considered obese .
a bmi > 30  kg / m has a negative impact on health and is associated with premature atherosclerosis , increased risk of myocardial infarction , and heart failure .
severe obesity is associated with decreased survival , largely because of cardiovascular deaths [ 3 , 4 ] .
most echocardiographic studies assessing left ventricular ( lv ) systolic function in obese patients used ejection phase indices like lv ejection fraction and lv fractional shortening .
they reported normal or hyperdynamic lv systolic function and no or little differences in lean and obese subjects [ 5 , 6 ] .
impaired lv systolic function in persons with obesity was only found in the presence of coexistent heart disease .
more recent echocardiography technics like tissue - doppler and strain imaging have revealed evidence of subclinical lv systolic dysfunction in subjects with obesity , even in the presence of normal lv ejection phase indices [ 8 , 9 ] .
alterations in cardiac function have also been shown to be reversible with weight reduction strategies [ 10 , 11 ] .
weight loss after interventions like bariatric surgery and dietary weight reduction can be beneficial to cardiovascular structure and function and result in a decrease in cardiovascular risk and total mortality [ 1214 ] .
the purpose of this study was to examine systolic left ventricular function and the effect of diet - induced weight loss in patients with severe obesity by transthoracic two - speckle - tracking echocardiography ( ste ) with lv strain imaging .
the study was approved by the ethics committee of the state medical council of hessen , germany ( approval number ff 112/2015 ) .
all patients were participants in the optifast-52 diet program ( nestl health science , frankfurt , germany ) , which ran for a total of 52 consecutive weeks .
the specifics of the program included a fasting phase of 12 weeks with ingestion of food restricted to formula products with a high protein content .
a subsequent transitional phase and a final stabilization phase aim to introduce the patients to a balanced diet . for the duration of the program , all patients received psychological , physiotherapeutic , medical , and nutritional care .
inclusion criteria were as follows : age 18 and 65 years , bmi > 30 
kg / m , secondary and accompanying conditions requiring treatment such as hypertension , hypercholesterolemia , diabetes mellitus , and illnesses of the locomotor system .
all patients had made repeated ( at least three ) unsuccessful attempts to reduce weight .
exclusion criteria were cardiac arrhythmia , recent myocardial infarction , severe ( malign ) general illnesses , pregnancy and nursing , or a documented eating disorder .
total body composition and fat content was also measured using the dual energy x - ray absorptiometry ( dxa ) in week 1 and in week 12 .
echocardiography was performed using a commercially available ultrasound machine ( vivid 7 , ge healthcare , horten , norway ) and a 3.5  mhz ( 3s - rs ) transducer .
patients were examined in a resting , left - lateral position and , for specific parts of the examination , in end - expiration by an experienced examiner .
all images were obtained from standard parasternal and apical position using 2d and m - mode echocardiographic techniques .
lv ejection phase indices like lv ejection fraction and fractional shortening were calculated from parasternal m - mode measurements .
two - dimensional ste analysis was performed offline using dedicated automated software ( echopac pc , version 6.0 , ge healthcare , horten , norway ) . from the apical and parasternal short - axis datasets ,
the software divided the lv into six segments and performed speckle - tracking analysis throughout one cardiac cycle .
finally , the software automatically created the time - domain lv strain curves in six segments , from which end - systolic strain was calculated .
global longitudinal peak systolic strain ( glps ) was defined as the averaged longitudinal strains at end - systole in 18 segments from three apical views . global radial strain ( grs )
was defined as averaged radial strain at end - systole in 18 segments from three levels of short - axis views .
dxa is a common measurement of human body composition based on a three - compartment model .
it divides the body into total body mineral , fat - free soft mass , and fat tissue mass .
body composition was evaluated by dxa with the use of a hologic densitometer ( qdr discovery wi , hologic inc . ,
measurements were taken with the patient lying in the supine position on the scanning table .
the results are expressed as mean  standard deviation ( sd ) for continuous variables .
for the descriptive statistics , the arithmetic mean , sd , median , minimum and maximum , and first and third quartiles were calculated . for the comparison of two measurements at different times ,
statistical analyses were performed using a statistical software package ( bias for windows , version 11.0 ) .
body weight decreased significantly from week 1 to week 12 of the weight loss program ( figure 2 ) .
the number of patients with arterial hypertension defined as blood pressure > 140  mmhg systolic and > 90  mmhg diastolic decreased from 9 patients to 1 patient .
mean systolic blood pressure was significantly reduced from 148  16 to 130  17  mmhg and diastolic blood pressure from 95  14 to 82  9  mmhg .
the mean heart rate also decreased significantly from 94  16 to 82  9 beats per minute , respectively .
total body fat mass decreased by 19% ( mean ) from 50.9  20.9  kg to 41.1  16.9  kg .
changes in fat distribution resulting from the 12 week fasting phase are reported in table 2 .
grading of the image quality before weight loss was good in 9 , moderate in 7 , and poor in 5 patients .
after weight loss , image quality improved to good in 11 , moderate in 7 , and poor in 3 patients .
lv ejection phase indices , lv ejection fraction and fractional shortening , were within normal range at baseline and remained unchanged after weight loss ( table 3 ) .
glps at baseline was 18.7  3.2 in week 1 and 18.8  2.4 in week 12 ( figure 3 ) .
no significant correlation was noted between glps and bmi ( r = 0.36 , p = ns ) .
we found a weak but not significant correlation between percentage weight loss and increase in glps ( r = 0.39 , p = ns ) .
also , no significant change in grs after weight loss was noted ( 41.1  22.0 versus 43.9  23.3 , p = 0.09 ) . the left atrial diameter ( anterior - posterior ) measured in the parasternal long - axis view
weight reduction after 12 weeks of diet was associated with a decrease in left atrial size , but the difference was not significant ( table 3 ) . left atrial volume , lv wall thickness , and lv end - diastolic diameter were within normal range at baseline and remained unchanged after weight loss .
variable findings have been reported with respect to systolic function in obese subjects , including preserved or mildly reduced left ventricular function .
interestingly , these alterations have been shown to be reversible with weight reduction therapies [ 10 , 17 ] .
lv ejection fraction appears to be clinically the most relevant parameter . however , lv ejection fraction has some limitations .
the most important , it is not sensitive enough to detect subtle alterations in the contractile function and therefore not suitable for detecting subclinical myocardial damage . in some studies ,
tissue - doppler echocardiography has been able to show the presence of subclinical systolic contractile abnormalities , although the left ventricular ejection fraction remained within the normal range [ 8 , 9 , 1922 ] .
two - dimensional ste is a new gray - scale based technique that provides angle - independent measurements of myocardial deformation and has the potential for quantitative assessment of systolic left ventricular function [ 18 , 23 ] .
speckles are produced as a result of the scatter of the ultrasound beam by the tissue . by tracking frame by frame the displacement of the speckles during the cardiac cycle , strain
, software automatically resolves the magnitude of myocardial deformation in different directions and generates strain .
strain is the percentage change in the length of a myocardial segment during a cardiac cycle and has the unit % . in the present study ,
lv ejection phase indices , lv ejection fraction and fractional shortening , were normal at baseline and unchanged at follow - up . also , systolic left ventricular function quantified by glps and grs was normal .
we found glps and grs values in a range comparable to values defined as normal in a large meta - analysis including 2,597 subjects from 24 studies .
other studies in obese individuals without cardiac disease reported similar lv ejection fraction but worse systolic mechanics as assessed by glps when compared with nonobese controls [ 2527 ] .
a recent study by leung et al . found a significant improvement in both systolic and diastolic myocardial function measured by longitudinal strain in obese patients with type 2 diabetes and weight loss 9 months after sleeve gastrectomy . a behavioural intervention program including dietary restrictions and exercise training in obese patients found an increase in strain measured by tissue - doppler myocardial imaging in patients with significant reduction of weight after 6 months .
in contrast to other studies we could not find a significant increase in glps or grs after weight loss . this might be due to a shorter follow - up period , a lower rate of concomitant diseases , and different weight loss strategies [ 30 , 31 ] . in moderate - to - severe cases of obesity , increased cardiac output as a result of the high metabolic activity of excessive fat may lead to left atrial and ventricular dilation , increased lv wall stress , and compensatory ( eccentric ) lv hypertrophy [ 32 , 33 ] . in the present study ,
mean lv diameter and thickness of the lv wall were normal at baseline and remained unchanged after 12 weeks on the diet .
an echocardiographic study in obese patients with a bmi of 50.0  1.4 who underwent bariatric surgery reported a decrease in lv dilatation and hypertrophy after a longer follow - up period of 13  4 months .
other studies have also shown a decrease in lv mass and size one to three years after weight reduction interventions [ 7 , 35 , 36 ] .
similar findings were reported in patients with obesity after gastric bypass surgery [ 36 , 37 ] .
lifestyle and diet therapies have demonstrated some cardiovascular benefits . the data from a number of recent meta - analyses ,
however , suggests that bariatric operations result in larger benefits to cardiovascular risk parameters than other weight loss therapies . however , no randomized controlled trials currently exist comparing the effects of bariatric surgery with standardized nonsurgical treatments , specifically focusing on cardiovascular end points .
the small number of the study groups limits interpretation of the results , in particular p values .
we were unable to demonstrate cardiac changes due to obesity such as lv hypertrophy and enlargement or atrial dilatation as described by other authors .
however , patients in our group were relatively young ( mean age 43 years ) in terms of the risk of other causes of structural cardiac abnormalities .
glps measured by ste in order to determine systolic function is in part heart rate and blood pressure - dependent and is subject to change within any given patient .
finally , when studying people with obesity , echocardiographic measurements may be error - prone or imprecise .
in our study , obesity was not associated with systolic dysfunction measured by ste with strain imaging .
dimensions of left atrial and ventricular structures were normal at baseline and not altered after weight loss .
diet with successful weight reduction goes along with reduction in blood pressure and heart rate .
 obesity is associated with an increased risk of heart failure . 
 little is known about the impact of dietary changes on the cardiac sequelae in obese patients . 
 twenty - one obese subjects underwent a 12-week low calorie fasting phase of a formula diet . 
 transthoracic two - dimensional speckle - tracking echocardiography was performed to obtain systolic left ventricular strain before and after weight loss . 
 body mass index decreased significantly from 38.6  6.2 to 31.5  5.3  kg / m2 , and the total percentage fat loss was 19% . 
 weight reduction was associated with a reduction in blood pressure and heart rate . left ventricular longitudinal global peak systolic strain was in the lower normal range ( 18.7  3.2% ) before weight loss and was unchanged ( 18.8  2.4% ) after 12 weeks on diet with substantial weight loss . 
 also , no significant change in global radial strain after weight loss was noted ( 41.1  22.0 versus 43.9  23.3 , p = 0.09 ) . left atrial and ventricular dimensions were in normal range before fasting and remained unchanged after weight loss . in our study obesity 
 was associated with normal systolic left ventricular function . 
 a 12-week low calorie diet with successful weight loss can reduce blood pressure and heart rate . 
 systolic left ventricular function and morphology were not affected by rapid weight reduction . 
1. Introduction
2. Methods
3. Results
4. Discussion
5. Conclusion