In morbidly obese patients with hypertension, bariatric surgery improved cardiovascular outcomes and reduced all-cause mortality, suggesting it should be considered as a treatment option for this group, scientists said.
Among more than 11,000 patients followed for approximately 5 years, those who underwent bariatric surgery had a 27% risk reduction for major adverse cardiac events (HR 0.73, 95% CI 0.64-0.84, P<0.001) compared to matched controls who did not have surgery, after adjusting for comorbidities and other factors, said researchers led by Erik Stenberg, MD, PhD, of Örebro University in Sweden.
Reporting online in PLOS Medicine, Stenberg’s team said that the surgery group had lower risk for acute coronary syndrome events (HR 0.52, 95% CI 0.41-0.66, P<0.001) and showed a trend toward lower risk for cerebrovascular events (HR 0.81, 95% CI 0.63-1.01, P=0.060). The surgery group also had lower risk for all-cause mortality (HR 0.84, 95% CI 0.73-0.97, P=0.017) but no significant risk reduction in cardiovascular mortality (HR 0.94, 95% CI 0.71-1.25, P=0.682), the study found.
“There is compelling evidence that metabolic surgery on patients with type 2 diabetes [T2DM] and morbid obesity leads to reduced risk for acute cardiovascular events, but the effect on patients with hypertension and morbid obesity remains unclear,” the researchers wrote. “The major risk reduction for patients with hypertension … appears to be more cardiovascular than cerebrovascular, which is in agreement with previous reports for patients with T2DM and morbid obesity.”
Significantly more patients in the surgery group discontinued hypertensive medication in the 2 to 4 years after surgery (30.7% vs 9.2% in the control group, P<0.001), suggesting their hypertension was in remission, the researchers said. However, the study did not include actual blood pressure measurements, which was a main limitation, they added.
“The discontinuation and true remission of hypertension has recently been questioned, and indeed, relapse of hypertension amongst patients with early remission has been reported to be high,” they said. “The main benefit of metabolic surgery for patients with hypertension may thus not be remission of hypertension itself, but rather a combination of protective cardiometabolic effects. The effects of bariatric surgery on glucose metabolism and T2DM are well documented, and the high remission rates of T2DM in the present study supports this.”
Stenberg and colleagues analyzed data on 11,863 patients from national registries, including the Swedish National Patient Register and the Swedish Prescribed Drug Register. All of these patients were morbidly obese and had pharmacologically treated hypertension, and they all underwent bariatric surgery. Mean age was 52 and mean body mass index (BMI) before surgery was 49.1. There were more women (68%) than men. Most of the patients underwent gastric bypass (90%). The other 10% had sleeve gastrectomy. The vast majority of procedures (96%) were laparoscopic.
The control group consisted of 26,199 individuals with hypertension who did not have metabolic surgery, matched to the surgery group for age, sex, and area of residence. Matching ratios varied from 1:1 to 1:9. Mean follow-up time was approximately 5 years. The main outcome was a major adverse cardiac event. Secondary outcomes were specific cardiac events, including a first episode of acute coronary syndrome or stroke, as well as cardiac-specific and all-cause mortality. The researchers used Cox regression and Poisson regression analyses, adjusted for comorbidities including dyslipidemia, diabetes, and chronic obstructive pulmonary disease. They also adjusted for age, sex, surgical method, and duration of hypertension.
In addition to the lack of blood pressure measurements, limitations of the study included a lack of data on BMI and smoking history in the control group, the researchers noted. Although they compensated for known risk factors in their analyses, it is possible that the overall healthier patients in the control group may have resulted in an underestimation of treatment effects in the surgery group, they said.
Nevertheless, “The study indicates that metabolic surgery (gastric bypass and sleeve gastrectomy) is associated with reduced risk for major adverse cardiovascular events for patients with hypertension and morbid obesity, suggesting that metabolic surgery should be considered in the treatment of patients with hypertension and morbid obesity,” they said.
The study was funded by grants from Region Örebro County, the Bengt Ihre Foundation, the Stockholm County Council, SRP Diabetes, and the Novo Nordisk Foundation.
No study authors reported conflicts of interest.