Study: Echocardiography may reveal keys to ‘obesity paradox’ in heart failure

Researchers have grappled with the so-called “obesity paradox” for years. Some have found that a high bodyweight is linked to improved survival after cardiovascular events like stroke and heart failure, while others contend being overweight both raises the odds of CVD and isn’t protective after a diagnosis, either.

A study presented Dec. 6 at the EuroEcho-Imaging 2018 conference in Milan adds to this debate, finding that acute heart failure patients with a body mass index (BMI) of 23 or higher had better survival over nearly three years of follow-up than those with a BMI below that threshold.

Commonly used BMI cutoffs for overweight and obese are 25 and 30, respectively, so the “overweight-to-obese” cohort in this study also encompassed some individuals who were at the top end of what many consider to be normal weight.

Nevertheless, those heavier patients who were deemed metabolically healthy had the best survival (79.4 percent) over a median follow-up of 33.7 months. Even metabolically unhealthy obese patients—who had risk factors such as high blood pressure, high cholesterol or glucose intolerance—showed a 66.5 percent survival rate, higher than normal-weight individuals with good (63.9 percent) or poor metabolic health (55.5 percent).

The study included 3,564 patients admitted to a hospital with acute heart failure over a seven-year span, 56.7 percent of whom were overweight or obese.

Echocardiographic findings revealed that patients in the high BMI group had lower rates of eccentric left ventricular (LV) hypertrophy compared to normal weight participants (62.4 percent versus 49.1 percent). They also averaged higher LV ejection fractions at 41.6 percent versus 38.9 percent, and had marginally higher global longitudinal strain (GLS).

“Our findings provide insights into why obesity is protective in patients with heart failure,” lead author Chan Soon Park, a cardiologist at Seoul National University Hospital in South Korea, said in a press release. “Based on our study, obese patients have less eccentric hypertrophy and greater LV GLS and LV ejection fraction, meaning there is less deterioration in the structure and function of the heart.”

Park said the assessment of heart structure and function, along with metabolic health criteria, could help clinicians identify patients at higher risk of premature death.

“Further studies are needed to see if preventing and treating metabolic abnormalities—for example with statins and blood pressure lowering medications—can improve the prognosis of overweight and obese patients with heart failure,” he said.