Higher BMI Linked With Lower Mortality in Adult Congenital Heart Disease

A retrospective study recently published in Heart found that adults with congenital heart disease who had higher body mass indices (BMI) had lower mortality rates.¹

Obesity affects more than one-third of US adults, according to statistics from the Centers for Disease Control and Prevention (CDC), and it has been linked with numerous health problems such as cardiovascular disease, cancer, and arthritis.^2-4 Contrary to these observations, however, obesity may have a protective effect in some cases.

While it has been associated with higher mortality in the general population and certain cardiovascular cohorts, emerging research suggests that there may be an “obesity paradox,” meaning that a higher BMI may be related to better survival in patients with long-term chronic disease — for example, kidney disease, chronic heart failure, and chronic obstructive pulmonary disease.^5-7

Citing mixed and limited data regarding obesity and outcomes in patients with ACHD, researchers from several international universities examined associations between BMI and mortality in this patient population. They reviewed data pertaining to 3069 adult patients with congenital heart disease (48% women; median age, 32.6 years) who were followed at a London hospital over a 15-year period.

Patients were classified by BMI according to World Health Organization (WHO) recommendations: 6.2% were underweight (BMI <18.5 kg/m²); 51.1% were of normal weight (BMI = 18.5-24.9 kg/m²); 28.2% were overweight (BMI ≥25-29.9 kg/m²); and 14.6% were obese (BMI ≥30 kg/m²).

The findings demonstrate an association between higher BMI and lower all-cause and cardiac mortality, even when adjusting for age, defect complexity, cyanosis, and objective exercise capacity. The BMI category linked with the lowest mortality risk was 34.1kg/m².

There was an especially strong association between higher BMI and better prognosis in adult patients with symptomatic congenital heart disease (hazard ratio [HR]: 0.94; 95% CI, 0.90-0.98; P =.002) and complex underlying cardiac defects (HR: 0.96; 95% CI, 0.91-0.997; P =.048). In addition, an association was observed between weight loss and worse survival rates in patients with a complex cardiac defect (HR: 1.82; 95% CI, 1.02-3.24; P =.04).

In contrast to apparent benefits of lower body weight in the general population and certain patient groups, the “complex, symptomatic [adults with congenital heart disease] may fare better when maintaining a higher BMI similarly to patients with [heart failure] due to acquired heart disease,” the researchers wrote.

Although further research is needed, the present study suggests that “an uncritical approach advising [adults with congenital heart disease] to lose weight simply to prolong survival is not supported by the current data.”

Reference

1. Brida M, Dimopoulos K ,Kempny A, et al. Body mass index in adult congenital heart disease [published online February 25, 2017] . Heart. doi:10.1136/heartjnl-2016-310571
2. US Centers for Disease Control and Prevention. Adult obesity facts. www.cdc.gov/obesity/data/adult.html. Last updated September 1, 2016. Accessed March 16, 2017.
3. Jiang L, Tian W, Wang Y, et al. Body mass index and susceptibility to knee osteoarthritis: a systematic review and meta-analysis. Joint Bone Spine. 2012;79(3):291-297.
4. Daïen CI, Sellam J. Obesity and inflammatory arthritis: impact on occurrence, disease characteristics and therapeutic response. RMD Open. 2015;1(1):e000012. doi:10.1136/rmdopen-2014-000012.
5. Lainscak M, von Haehling S, Doehner W, Anker SD. The obesity paradox in chronic disease: facts and numbers. J Cachexia Sarcopenia Muscle. 2012;3(1):1-4.
6. Davos CH, Doehner W, Rauchhaus M, et al. Body mass and survival in patients with chronic heart failure without cachexia: the importance of obesity. J Card Fail. 2003;9(1):29-35.
7. Horwich TB, Fonarow GC, Hamilton MA, MacLellan WR, Woo MA, Tillisch JH. The relationship between obesity and mortality in patients with heart failure. J Am Coll Cardiol. 2001;38(3):789-795.