Weight loss could play role in managing patients with heart failure and obesity

A new study published in the Journal of the American College of Cardiology suggests that the obesity-survival paradox may be misleading.

For over 20 years, doctors have been puzzled by an apparent paradox. Patients living with heart failure and overweight (or obesity) often seemed to survive longer than those with heart failure and a healthy weight.

This so-called ‘obesity-survival paradox’ has influenced clinical guidelines, leading health care professionals to question whether weight loss is beneficial in patients living with heart failure.

The research team wanted to establish whether higher body mass index (BMI) is associated with negative health outcomes in patients with heart failure. BMI is a measure of body weight and can be used to estimate body fat. They also wanted to establish if BMI has different effects depending on the type of heart failure a patient has.

To do this, researchers analysed health data from thousands of heart failure trial participants. They used a genetic technique called Mendelian randomisation to test whether higher BMI genuinely causes worse outcomes in people with established heart failure.

Standard observational studies can be distorted by factors such as pre-existing illness and medication use. The genetic approach helps rule out many of these biases.

When the team used conventional statistical methods, they found the familiar obesity paradox. Heavier patients appeared to do better.

However, when they applied the genetic analysis, the picture reversed. Higher BMI was associated with a greater risk of:

• Death from any cause
• Death from heart disease
• Hospitalisation for heart failure

The study also examined whether the type of heart failure a patient has affects their health outcomes. Researchers wanted to know if the relationship changed depending on whether the heart’s pumping function was reduced or preserved. They found that it did not.

Dr Nicholas Sunderland, Wellcome GW4 Clinical Doctoral Fellow and lead author, said:

“Our genetic analysis found that higher BMI is associated with an increased risk of death in heart failure patients, in opposition to the obesity-survival paradox.

Findings from our study support the potential benefit of weight loss interventions for patients with heart failure across all types and may provide a rationale for future clinical trials in this area.”