Bariatric surgery induced remission of hypertension in obese patients and diminishes medication
GATEWAY - Effects of Bariatric Surgery in Obese Patients with Hypertension
Presented at AHA 2017 Scientific Sessions in Anaheim, CA, USA by Carlos Schiavon (Heart Hospital, Sao Paulo, Brazil
About 40% of American adults are obese, and 60-70% of hypertension in adults is attributable to adiposity. Observational and randomized trials (mainly focusing on T2DM) showed reduction or discontinuation of antihypertensive medication and overall reductions of CV events after bariatric surgery. RCTs in a population of hypertensive obese patients have not been performed yet. Bariatric surgery is a safe and effective method to treat obesity, and amelioration of hypertension is a potential beneficial effect of the procedure.
The GATEWAY aimed to evaluate whether bariatric surgery can provide a safe and effective auxiliary tool for blood pressure control in obese hypertensive patients. Reduction in antihypertensive medications can help in adherence to treatment. It was a single-center, open-label, randomized clinical trial to evaluate the efficacy of gastric bypass (Roux-en-Y) in reducing the prescription of antihypertensive drugs and its effect on hypertension and other CV risk factors. Patients with on average a BMI of about 37 kg/m2 (inclusion: BMI 30.0-39.9) were randomized (1:1) to either gastric bypass plus medical therapy, or to medical therapy alone (lifestyle intervention with visits to cardiologist, nutritionist and psychologist). At baseline, patients used a median of 3 antihypertensive drugs. The primary endpoint was reduction of at least 30% of antihypertensive drugs, maintaining BP <140/90 mmHg, at 12 months. Antihypertensive regimen was adapted to achieve the BP target of <140/90 mmHg.
- 83.7% Of patients in the gastric bypass group achieved the primary endpoint, as compared with 12.8% of patients in the control group (rate ratio: 6.6, 95%CI: 3.1-14.0, P<0.001).
- 51% (25/49) Of patients showed a remission of hypertension after bariatric surgery, while no patients on medical therapy only showed remission.
- Considering the SPRINT target, 32.7% of patients achieved the primary endpoint while maintaining SBP of <120 mmHg after gastric bypass, as compared with 8.5% of patients on medical therapy. Under these conditions, 22.4% (11/49) of patients in the gastric bypass group showed remission.
- Change in BMI from baseline was up to about 11 points at 12 months (showing a gradual decline) after bariatric surgery, as compared to no change in the control group.
- The effects on the primary endpoint happened early, visible from 1 month onwards, and before the weight change occurred.
- Of secondary endpoints, waist circumference showed a significant reduction in the bariatric surgery group (86.9±8.5 vs. 109.8±9.6, P<0.001) as did fasting plasma glucose (84.0±6.8 vs. 98.4±19.0, P<0.001) and triglycerides (85.7±46.2 vs. 130.0±5.0, P<0.001).
- The median number of antihypertensive drugs was 1 (IQR: 0-1) vs. 3 (IQR: 2.5-4) in the control group (mean: 0.7±1.0 vs. 3±0.9).
- Significantly more anemia was seen in the gastric bypass group at 12 months, as compared to baseline (20% vs 6 %, P=0.01), and hypovitaminosis B12 increased (28% vs 9%, P=0.01). 12% of patients (6/49) needed rehospitalization after gastric bypass, as compared to nobody in the control group (P=0.03).
The GATEWAY study shows that bariatric surgery represents an effective strategy in the treatment of obese patients with hypertension. These results are relevant in the context of minimizing non-adherence to therapy and its related consequences. Considering the improved metabolic and inflammatory profile, the observed effects have, in theory, the potential to reduce major CV events.
Discussant Paul Poirier (Quebec Heart and Lung Institute, Quebec, Canada) said that the GATEWAY trial is one of the biggest bariatric surgery trials. He noted that those patients technically do not fulfill criteria for bariatric surgery, as the minimal BMI is normally 40, of 35 with comorbidities. In the trial, patients were quite young (43.8±9.2 years). Only 4 were lost to follow-up. The observed remission of hypertension was true both based on office and ABPM 24-hour blood pressure. Considering SPRINT-insights, he proposed that maybe we should go even lower in obese patients.
The literature of bariatric surgery speaks of a broad range of positive effects, but most of the data was obtained in the diabetes remission world. This is the first study showing hypertension as a primary outcome. It confirms that bariatric surgery can do good things. Possible mechanisms include an effect on insulin resistance (renal sodium reabsorption and increased sympathetic tone), or on the renin-angiotensin-aldosterone system, gut hormones (GLP-1 and peptide YY may play a role in the entero-renal axis) or inflammation (modulation of arterial stiffness).
The question remains what this means for more obese patients. It is currently unknown and the main challenge in BP measurement is that upper arms are frequently short, large and conical. Overall, Poirier concluded that this trial confirms the results of observational studies, with better control of residual confounding due to the randomized and standardized design.
- Our reporting is based on the information provided at the AHA 2017 congress -