Objective

Overweight and obesity are often assumed to be risk factors for postprocedural mortality in patients with coronary artery disease (CAD). However, recent studies have described an "obesity paradox" -- a neutral or beneficial association between obesity and mortality postcoronary revascularization. We reviewed the effect of overweight and obesity systematically on short- and long-term all-cause mortality post-coronary artery bypass grafting (CABG) and post-percutaneous coronary intervention (PCI).

Methods

We searched the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, Scopus, and Web of Science to identify cohort, case control, and randomized controlled studies evaluating the effect of obesity on in-hospital/short-term (within 30 days) and long-term (up to 5 years) mortality. Full-text, published articles reporting all-cause mortality between individuals with and without elevated BMI were included. Two reviewers independently assessed studies for inclusion and performed data extraction.

Results

Twenty-two cohort publications were identified, reporting results in ten post-PCI and twelve post-CABG populations. Compared to individuals with non-elevated BMI levels, obese patients undergoing PCI had lower short- (odds ratio (OR) 0.63; 95% confidence interval (CI) 0.54-0.73) and long-term mortality (OR 0.65; 95% CI 0.51-0.83). Post-CABG, obese patients had lower short-term (OR 0.63; 95% CI 0.56-0.71) and similar long-term (OR 0.88; 95% CI 0.60-1.29) mortality risk compared to normal weight individuals. Results were similar in overweight patients for both procedures.

Conclusions

Compared to non-obese individuals, overweight and obese patients have similar or lower short- and long-term mortality rates postcoronary revascularization. Further research is needed to confirm the validity of these findings and delineate potential underlying mechanisms.

Background

In patients with chronic heart failure (CHF), previous studies have reported reduced mortality rates in patients with increased body mass index (BMI). The potentially protective effect of increased BMI in CHF has been termed the obesity paradox or reverse epidemiology. This meta-analysis was conducted to examine the relationship between increased BMI and mortality in patients with CHF.

Methods

We searched the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, Scopus, and Web of Science to identify studies with contemporaneous control groups (cohort, case-control, or randomized controlled trials) that examined the effect of obesity on all-cause and cardiovascular mortality. Two reviewers independently assessed studies for inclusion and performed data extraction.

Results

Nine observational studies met final inclusion criteria (total n = 28,209). Mean length of follow-up was 2.7 years. Compared to individuals without elevated BMI levels, both overweight (BMI approximately 25.0-29.9 kg/m(2), RR 0.84, 95% CI 0.79-0.90) and obesity (BMI approximately > or =30 kg/m(2), RR 0.67, 95% CI 0.62-0.73) were associated with lower all-cause mortality. Overweight (RR 0.81, 95% CI 0.72-0.92) and obesity (RR 0.60, 95% CI 0.53-0.69) were also associated with lower cardiovascular mortality. In a risk-adjusted sensitivity analysis, both obesity (adjusted HR 0.88, 95% CI 0.83-0.93) and overweight (adjusted HR 0.93, 95% CI 0.89-0.97) remained protective against mortality.

Conclusions

Overweight and obesity were associated with lower all-cause and cardiovascular mortality rates in patients with CHF and were not associated with increased mortality in any study. There is a need for prospective studies to elucidate mechanisms for this relationship.

Objective

To explore the covariate-adjusted associations between body composition (percent body fat and lean body mass) and prognostic factors for mortality in patients with chronic heart failure (CHF) (nutritional status, N-terminal pro-B-type natriuretic peptide [NT-proBNP], quality of life, exercise capacity, and C-reactive protein).

Patients and methods

Between June 2008 and July 2009, we directly measured body composition using dual energy x-ray absorptiometry in 140 patients with systolic and/or diastolic heart failure. We compared body composition and CHF prognostic factors across body fat reference ranges and body mass index (BMI) categories. Multiple linear regression models were created to examine the independent associations between body composition and CHF prognostic factors; we contrasted these with models that used BMI.

Results

Use of BMI misclassified body fat status in 51 patients (41%). Body mass index was correlated with both lean body mass (r=0.72) and percent body fat (r=0.67). Lean body mass significantly increased with increasing BMI but not with percent body fat. Body mass index was significantly associated with lower NT-proBNP and lower exercise capacity. In contrast, higher percent body fat was associated with a higher serum prealbumin level, lower exercise capacity, and increased C-reactive protein level; lean body mass was inversely associated with NT-proBNP and positively associated with hand-grip strength.

Conclusion

When BMI is divided into fat and lean mass components, a higher lean body mass and/or lower fat mass is independently associated with factors that are prognostically advantageous in CHF. Body mass index may not be a good indicator of adiposity and may in fact be a better surrogate for lean body mass in this population.

Background

We examined the validity of leg-to-leg bioelectrical impedance analysis (BIA) and near-infrared interactance (NIR) to assess body composition in chronic heart failure (CHF) patients.

Methods and results

A total of 140 patients with CHF were enrolled in this cross-sectional study between June 2008 and July 2009. Dual energy x-ray absorptiometry (DEXA) served as the reference standard. A priori, desired precision levels were set at ± 3.5% body fat and ± 3.5 kg lean body mass. Mean age was 63, 74% were male, and 90% were Caucasian. BIA- and NIR-ascertained percent body fat and lean body mass were highly correlated to DEXA. Mean differences and limits of agreement for NIR were -0.3% ± 5.1% for percent body fat and 2.9 kg ± 4.3 kg for lean body mass. Mean difference and limits of agreement for BIA percent body fat was 0.8% ± 5.8%. BIA lean body mass showed poor agreement with DEXA because of variable limits of agreement across the range of measurement (Pitman's test P < .0001).

Conclusions

In patients with CHF, both NIR and BIA accurately measure body fat. However, both methods were imprecise. NIR overestimated lean body mass and BIA was not useful to assess this parameter. Further study is required, including examination of the utility of these field methods in serially assessing body composition.

How well anthropometric indices such as body mass index (BMI), waist circumference, waist-stature ratio, and waist index correlate with direct measures of body composition (lean body mass, body fat) in men and women with chronic heart failure (CHF) has not been reported. Body composition was assessed by dual-energy x-ray absorptiometry in 140 patients with CHF. Age-adjusted Pearson correlations between each index and measures of body composition for men and women were calculated. Diagnostic accuracy of detecting obesity or high central fat was also examined. In men, all of the anthropometric indices except waist index were just as strongly correlated with lean body mass (correlation coefficients varied between 0.56 for waist-stature ratio to 0.74 for BMI) as with percentage of body fat (correlation coefficients varied between 0.72 for BMI to 0.79 for waist circumference). In women, all 4 anthropometric measures were unable to significantly differentiate between body fat and lean body mass. The positive likelihood ratios for the detection of obesity varied between 2.26 for waist circumference and 3.42 for BMI, waist-stature ratio, and waist index. Anthropometric indices do not accurately reflect body composition in patients with CHF, especially in women. When accurate assessment of body composition is required, direct measurements should be obtained.

Aims Our objective was to examine the association between body mass index (BMI) and survival according to the type of treatment in individuals with established coronary artery disease (CAD). Methods and results Patients with CAD were identified in the Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease (APPROACH) registry between January 2001 and March 2006. Analyses were conducted separately by treatment strategy [medical management only, percutaneous coronary intervention (PCI), or coronary artery bypass grafting (CABG)]. Patients were grouped according to six BMI categories. Multivariable-adjusted hazard ratios (HRs) for mortality were calculated using the Cox regression with the referent group for all analyses being normal BMI (18.5-24.9 kg/m(2)). The cohort included 31 021 patients with a median follow-up time of 46 months. In the medically managed only group, BMIs of 25.0-29.9 and 30.0-34.9 kg/m(2) were associated with significantly lower mortality compared with normal BMI patients (adjusted HR 0.72; 95% CI 0.63-0.83 and adjusted HR 0.82; 95% CI 0.69.0-0.98, respectively). In the CABG group, BMI of 30.0-34.9 kg/m(2) had the lowest risk of mortality (adjusted HR 0.75; 95% CI 0.61-0.94), whereas in the PCI group, BMI of 35.0-39.9 kg/m(2) had the lowest risk of mortality (adjusted HR 0.65; 95% CI 0.47-0.90). Patients who were overweight or have mild or moderate obesity were also more likely to undergo revascularization procedures compared with those with normal BMI, despite having lower risk coronary anatomy. Conclusion A paradoxical association between BMI and survival exists in patients with established CAD irrespective of treatment strategy. Patients with obesity may be presenting earlier and receiving more aggressive treatment compared with those with normal BMI.