New 22 Year Follow Up Study Shows Bariatric Surgery Associated with Lower Risk of Heart Failure in Obese Patients

Fahad Alkhalfan, M.D.
By Fahad Alkhalfan, M.D. on

In a study published in the European Heart Journal, Dr. Shabbar Jamaly and his team showed that in patients with obesity and no history of heart failure, being treated with bariatric surgery was associated with a reduced risk of heart failure.

The association between obesity and heart failure has been demonstrated in the past. Many studies have shown that patients with obesity and have up to two times increased risk of developing heart failure as compared to patients with a normal body mass index (BMI). Although the successful treatment of obesity has been shown to be associated with improved cardiovascular risk factors, the impact of weight loss on the development of heart failure is not known. Bariatric surgery is an effective and safe treatment option for sustained weight loss. The investigators used data from the Swedish Obese Subjects (SOS) study to compare the incidence of heart failure in obese patients who are treated with bariatric surgery and those who are managed with medical therapy alone.

“Among participants in the SOS study, persons treated with bariatric surgery had a lower risk of developing heart failure during long-term follow-up than did those receiving usual care. The risk of heart failure was reduced by 35% in the surgery group, despite a less favourable cardiovascular risk factor profile at baseline and a lower use of betablockers, renin–angiotensin system inhibitors and loop-diuretics during follow-up. The risk of heart failure appeared to decline in parallel with greater degrees of weight loss.” – Dr. Shabbar Jamaly, M.D.

The SOS study is an ongoing controlled trial that compares the effect of bariatric surgery and conventional obesity care on morbidity and mortality. The SOS trial previously demonstrated that bariatric surgery reduced mortality and cardiovascular morbidity in patients with obesity. The investigators identified 2,010 individuals with obesity who were treated with bariatric surgery and 2,037 control patients with similar baseline characteristics that were treated with the standard of care. Patients were followed for a median of 22 years and assessed for the occurrence of heart failure. Additionally, the patients were pooled together and divided into quartiles based on their degree of weight loss. Patients in the lowest quartile were then compared to those in the top quartile.

Out of the 4,047 patients identified, 14 were excluded due to a history of heart failure. A total of 4,033 patients were included in the final analysis (2,003 in the bariatric group and 2,030 in the conventional group). While most baseline characteristics were similar between the two groups, the patients in the bariatric surgery group had a higher baseline BMI value and were more likely to smoke, have hypertension and diabetes. Patients in the bariatric surgery group had a mean BMI of 42.4 kg/m2 as compared to 40.1 kg/m2 in the control group. Additionally, patients in the bariatric group experienced a reduction in BMI of 25% by the first year, by 18% at year 6, and by 16% at year 20, whereas the BMI of patients in the control group remained unchanged. A first-time diagnosis of heart failure occurred in 188 patients in the surgery group (9.4%) and 266 patients in the control group (13.1%). Patients in the bariatric group had a 35% lower risk of being diagnosed with heart failure (HR 0.65, 95% CI 0.54-0.79, p <0.001). Even after adjusting for baseline characteristics, the risk remained significant (HR 0.66, 95% CI 0.51-0.81, p <0.001). In the pooled population, the investigators found that the baseline conditions associated with heart failure were age, male sex, hypertension, diabetes, elevated cholesterol levels, smoking, and increasing thyroxine levels. The risk of heart failure declined as the degree of weight loss increased (adjusted HR 0.60, 95% CI 0.36-0.97, p = 0.038).

Despite a less favorable cardiovascular profile, patients in the bariatric group had a 35% lower risk of heart failure. When discussing the findings of the study, Dr. Jamaly highlighted the potential underlying mechanism behind this. He wrote, “The mechanism by which surgically induced weight loss may reduce the risk of heart failure is probably multifactorial. Bariatric surgery improves heart failure risk factors including hypertension, diabetes, and dyslipidaemia and lowers the incidence of cardiovascular events. The reversal of haemodynamic overload leads to regress of left ventricular hypertrophy and improves diastolic dysfunction.” While one strength of this study is its long period of follow up, it is important to consider some of its limitations.

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