The obesity paradox in patients with acute coronary syndrome: results from the Gulf RACE-2 study

The obesity paradox in patients with acute coronary syndromes over 2 decades - the ACSIS registry 2000-2018

BACKGROUND

Obesity is a worldwide epidemic which is associated with major cardiovascular (CV) risk factors. Nevertheless, substantial distant data, mostly published more than a decade ago, have demonstrated an obesity paradox, where obese patients generally have a better short- and long-term prognosis than do their leaner counterparts with the same CV profile. Nonetheless, it is not fully elucidated whether the obesity paradox is still relevant in the contemporary cardiology era among patients with acute coronary syndrome (ACS). We aimed to examine temporal trends in the clinical outcomes of ACS patients by their BMI status.

METHODS

Data from the ACSIS registry including all patients with calculated BMI data between the years 2002-2018. Patients were stratified by BMI groups to underweight, normal, overweight and obese. Clinical endpoints included 30d major cardiovascular events (MACE), and 1-year mortality. Temporal trends were examined in the late (2010-2018) vs. the early period (2002-2008). Multivariable models examined factors associated with clinical outcomes by BMI status.

RESULTS

Among the 13,816 patients from the ACSIS registry with available BMI data, 104 were underweight, 3921 were normal weight, 6224 were overweight and 3567 were obese. 1-year mortality was highest among underweight patients (24.8%), as compared to normal weight patients (10.7%) and lowest among overweight and obese patients (7.1% and 7.5% respectively; p for trend <0.001). 30-day MACE rates followed a similar pattern (24.3% for underweight, 13.6% for normal weight, 11.6% for overweight, and 11.7% for obese; p for trend<0.001). Comparing the 2 time-periods, 30-day MACE was significantly lower in the late period in all BMI groups, but unchanged in patients who were underweight. Similarly, 1-year mortality has decreased in normal weight and obese patients but remained similarly high in underweight patients.

CONCLUSIONS

In ACS patients, during 2-decades, 30-day MACE and 1-year mortality were lower among overweight and obese patients compared to underweight and even normal weight patients. Temporal trends revealed that 30-day MACE and 1-year mortality have decreased among all BMI groups other than the underweight ACS patients, among whom the adverse CV rates were consistently high. Our findings suggest that the obesity paradox is still relevant in ACS patients in the current cardiology era.

Relative Fat Mass Index can be solution for obesity paradox in coronary artery disease severity prediction calculated by SYNTAX Score

BACKGROUND

The relation between body mass index (BMI) and coronary artery disease (CAD) extension remains controversial. A new score was developed to estimate body fat percentage (BFP) known as Relative Fat Mass (RFM) Index. This study aimed to evaluate the value of RFM Index in predicting the severity of the CAD, compared with other anthropometric measurements.

METHODS

A total of 325 patients with chronic CAD were investigated. RFM, BFP, BMI and other anthropometric characteristics of patients were measured before angiography. CAD severity was determined by SYNergy between percutaneous coronary intervention with TAXus and cardiac surgery trial (SYNTAX) Score. The association between SYNTAX Score and variables was evaluated using linear regression models. In order to compare the model performance, R-squared (R²), Akaike's information criterion, Bayesian information criterion and root mean square error were used.

RESULTS

Univariate linear regression outcome variable, SYNTAX was used to determine whether there was any relationship between variables. Independent variables were included in the multivariable linear logistic regression models. The analysis showed that in model 1, RFM (β coefficient: 2.31 (0.90 to 3.71), p=0.001)), diabetes mellitus (β coefficient: 3.72 (1.67 to 3.76), p=0.004)), haemoglobin (β coefficient: -2.12 (-3.70 to -0.53), p=0.03) and age (β coefficient: 1.83 (0.29 to 3.37), p=0.02)) were statistically significant. The adjusted R² values in model 1 were higher than model 2 (BFP) and model 3 (BMI) (0.155, 0.137 and 0.130, respectively), and χ² values of RFM were higher than BFP and BMI (10.5, 3.4 and 1.0, respectively).

CONCLUSION

RFM Index is a more reliable and compatible marker of obesity in showing the severity of CAD compared to BMI.

Association of obesity indices with in-hospital and 1-year mortality following acute coronary syndrome

BACKGROUND/OBJECTIVES

According to the "obesity paradox", adults with obesity have a survival advantage following acute coronary syndrome, compared with those without obesity. Previous studies focused on peripheral obesity and whether this advantage is conferred by central obesity is unknown. The objective of this study was to describe the association of peripheral and central obesity indices with risk of in-hospital and 1-year mortality following acute coronary syndrome (ACS).

SUBJECTS/METHODS

Gulf COAST is a prospective ACS registry that enrolled 4044 patients age ≥18 years from January 2012 through January 2013, across 29 hospitals in four Middle Eastern countries. Associations of indices of peripheral obesity (body-mass index, [BMI]) and central obesity (waist circumference [WC] and waist-to-height ratio [WHtR]) with mortality following ACS were analyzed in logistic regression models (odds ratio, 95% CI) with and without adjustment for Global Registry of Acute Coronary Events risk score.

RESULTS

Of 3882 patients analyzed (mean age: 60 years; 33.3% women [n = 1294]), the prevalence of obesity was 34.5% (BMI ≥ 30.0 kg/m²), 72.2% (WC ≥ 94.0 cm [men] or ≥80.0 cm [women]) and 90.0% (WHtR ≥ 0.5). In adjusted models, deciles of obesity indices showed higher risk of mortality at extreme versus intermediate deciles (U-shaped). When defined by conventional cut-offs, peripheral obesity (BMI ≥ 30.0 versus 18.5-29.9 kg/m²) showed inverse association with risk of in-hospital mortality (0.64; 95% CI, 0.42-0.99; P = 0.04; central obesity showed trend toward reduced mortality). In contrast, for risk of 1-year mortality, all indices showed inverse association. Obesity, defined by presence of all three indices, versus nonobesity showed inverse association with risk of 1-year mortality (0.52; 95% CI, 0.35-0.75; P = 0.001). Results were similar among men and women.

CONCLUSION

The degree of obesity paradox following ACS depends on the obesity index and follow-up time. Obesity indices may aid in risk stratification of mortality following ACS.

Body composition phenotypes and obesity paradox

PURPOSE OF REVIEW

The obesity paradox is a highly controversial concept that may be attributed to methodological limitations related to its identification. One of the primary concerns is the use of BMI to define obesity. This index does not differentiate lean versus adipose tissue compartments (i.e. body composition) confounding health consequences for morbidity and mortality, especially in clinical populations. This review will describe the past year's evidence on the obesity paradox phenomenon, primarily focusing on the role of abnormal body composition phenotypes in explaining the controversies observed in the literature.

RECENT FINDINGS

In spite of the substantial number of articles investigating the obesity paradox phenomenon, less than 10% used a direct measure of body composition and when included, it was not fully explored (only adipose tissue compartment evaluated). When lean tissue or muscle mass is taken into account, the general finding is that a high BMI has no protective effect in the presence of low muscle mass and that it is the latter that associates with poor prognosis.

SUMMARY

In view of the body composition variability of patients with identical BMI, it is unreasonable to rely solely on this index to identify obesity. The consequences of a potential insubstantial obesity paradox are mixed messages related to patient-related prognostication.

“Obesity paradox” in coronary artery disease

Obesity used to be among the more neglected public health problems, but has unfolded as a growing medical and socioeconomic burden of epidemic proportions. Morbid obesity is linked to traditional cardiovascular risk factors like, hypertension, hyperlipidemia and diabetes, and suspected to incur increased morbidity and mortality in the Western and even third world populations. This patient cohort is also at greater risk to develop coronary artery disease. Recent population-based registries revealed that 43% and 24% of all cases of coronary revascularization were carried out in overweight and obese patients, respectively. However, despite evidence of a positive correlation between obesity and increased cardiovascular morbidity, some authors have described a better clinical outcome in overweight and obese patients, a phenomenon they coined “obesity paradoxon”. Thus, there is an ongoing debate in light of conflicting data and the possibility of confounding bias causing misconception and challenging the “obesity paradox”. In this review article we present the current evidence and throughly discuss the validity of the “obesity paradoxon” in a variety of clinical settings.