The Effect of Gastric Bypass Surgery on Hypertension in Morbidly Obese Patients

BACKGROUND: Hypertension is the most common medical disorder associated with obesity. The relationship between dietary weight loss and the reduction of blood pressure is well established. However, the effect of gastric bypass surgery on blood pressure has not been well studied. METHODS: We evaluated the relationship between weight loss and blood pressure in patients with diastolic hypertension who had gastric bypass surgery for morbid obesity. Patients were defined as hypertensive if taking antihypertensive medication or if both the preoperative office and mean hospital diastolic blood pressures were greater than 90 mmHg. Two of the authors (J.L.C., M.E.R.), blinded to all postoperative weights, classified the follow-up hypertensive status into one of four categories: resolved, improved, no change, or worse. The relationship between postoperative changes in blood pressure status and mean weight loss, percent excess weight loss, and body mass index were examined using a one-way analysis of variance. The relationship between postoperative weight loss and blood pressure was assessed in the baseline normotensive population using linear regression analysis. RESULTS: There were 45 patients with diastolic hypertension; 91% were taking an antihypertensive medication. The mean follow-up was 39 months. The mean preoperative weight was 137 kg and the mean weight loss at 1, 12, and 24 months following surgery was 13, 21, and 45 kg, respectively. Twelve months after surgery, hypertension had resolved in 22 patients (54%) and had improved in six patients (15%). These findings persisted through 48 months postoperatively. There was a significant relationship between the percentage of excess weight lost and improvement of hypertension at the 6-month and 12-month follow-up visits. There was also a significant relationship between the body mass index and improvement of hypertension at the 1-month, 12-month, 24-month, and 48-month follow-up visits. In the baseline normotensive patients there was not a significant relationship between our weight loss measures and changes in blood pressure. CONCLUSIONS: We conclude that postoperative weight loss in patients undergoing gastric bypass surgery was associated with resolution or improvement of diastolic hypertension in approximately 70% of cases. Resolution or improvement of hypertension occurred more often in patients with a lower postoperative body mass index.