A new study shows that obese individuals who have bariatric surgery have a reduced long-term incidence of cardiovascular deaths and events such as heart attack and stroke.

While most epidemiological studies have shown that obesity is associated with increased cardiovascular events and death, the researchers say weight loss might protect against cardiovascular events, but solid evidence is lacking.

Lars Sjostrom, M.D., Ph.D., of the University of Gothenburg, Sweden, and colleagues conducted an ongoing, nonrandomized, prospective, controlled study. It was conducted at 25 public surgical departments and 480 primary health care centers in Sweden. It includes 2,010 obese participants who underwent bariatric surgery and 2,037 matched obese controls who received usual care.

The patients were ages 37 to 60 years old and had a body mass index of at least 34 in men and at least 38 in women.

Surgery patients underwent gastric bypass (13.2 percent), banding (18.7 percent), or vertical banded gastroplasty (68.1 percent), and controls received usual care in the Swedish primary health care system, the authors said.

The average weight loss after 2, 10, 15, and 20 years was 23 percent, 17 percent, 16 percent, and 18 percent in the surgery group respectively. In the control group the average weight loss was 0 percent, 1 percent, 1 percent, and 1 percent.

There were 49 cardiovascular deaths among the patients in the control group and 28 cardiovascular deaths among the patients in the surgery group. There were 234 cardiovascular events in total among patients in the control group and 199 cardiovascular events among patients in the surgery group.

The researchers conclude that bariatric surgery was associated with a reduced number of fatal cardiovascular deaths and a lower level of total cardiovascular events.

"Alternatively, following relatively modest weight loss induced by bariatric surgery, there is no further risk reduction attributable to greater, subsequent weight loss. Our negative findings also emphasize the need to explore weight loss independent of effects of bariatric surgery," the authors wrote in JAMA.

Bariatric surgery was linked with a reduced number of fatal heart attacks, while 22 percent were those who have had surgery and 37 were those who were in the control group, no surgery.

"In conclusion, this is the first prospective, controlled intervention to our knowledge reporting that bariatric surgery is associated with reduced incidence of cardiovascular deaths and cardiovascular events,” the authors wrote.

“These results— together with our previously reported associations between bariatric surgery and favorable outcomes regarding long-term changes of body weight, cardiovascular risk factors, quality of life, diabetes, cancer, and mortality— demonstrate that there are many benefits to bariatric surgery and that some of these benefits are independent of the degree of the surgically induced weight loss."