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Troponin decrease after weight loss from bariatric surgery

Bariatric surgery and subsequent weight loss leads to marked reductions in cardiac troponin I levels, a marker of subclinical myocardial injury, suggests new research.

The finding with surgery was not seen in patients who followed an intensive lifestyle-intervention program, report investigators, who say it suggests that weight-reduction surgery may independently reduce cardiometabolic stress and the subsequent risk of heart failure in morbidly obese patients.

“Levels of cardiac troponins have been found to be strongly associated with unfavorable outcomes such as the development of heart failure and cardiovascular death,” lead author Dr Magnus Lyngbakken (Akershus University Hospital, Oslo, Norway) said.

“As circulating troponin levels are considered to be an index of subclinical cardiac stress and injury, these findings suggest an additional benefit of bariatric surgery.”

The current findings fit nicely with previously reported observations that bariatric surgery in some patients may reverse type 2 diabetes—which might be expected to lower the risk of CV disease, including heart failure, Lyngbakken added.

The study was published December 10, 2015 in the European Journal of Preventive Cardiology.

According to Dr Christie Ballantyne (Baylor College of Medicine, Houston, Texas), it’s known that obesity is an important risk factor for the development of heart failure, but it is not known whether treatment of obesity can treat or prevent heart failure.

“Indeed, we and others have observed the ‘obesity paradox,’ where obese individuals have better survival [than the nonobese] after developing heart failure,” he said in an email.

But Ballantyne, who isn’t connected with the current study, reaffirmed that troponin I is one of the most powerful predictors for assessing risk of which patients will develop heart failure.

“Therefore, this study is a very promising proof of concept that surgical treatment of obesity may be beneficial for prevention of heart failure in high-risk individuals who have elevated levels of troponin I,” he said, adding, however, that clearly a prospective clinical trial would be needed to test this hypothesis

Surgery vs Lifestyle Modification

Patients were enrolled in the MOBIL study, a yearlong, nonrandomized trial comparing the effect of Roux-en-Y gastric-bypass surgery and intensive lifestyle interventions on various comorbidities in morbidly obese patients. Some 136 patients completed the study, 74 in the surgical group and 62 in the lifestyle group. Outcomes in both treatment groups were compared with a normal-weight control group.

At baseline, 78% of patients allocated to the surgical group and 84% of those in the lifestyle-intervention group had detectable cardiac troponin I levels, vs 53% of the control group.

Cardiac troponin I levels fell by 0.80 ng/L after 12 months of follow-up in the bariatric-surgery group, compared with a reduction of 0.15 ng/L in the intensive lifestyle-intervention group (P<0.001), the group reported.

In fact, after 12 months of follow-up, cardiac troponin I levels in the surgery group did not differ significantly from baseline levels in the normal-weight control group. At baseline, median cardiac troponin I levels were similar at 2.40 ng/L in the surgery group vs 2.35 ng/L in the lifestyle-intervention group.

Baseline cardiac troponin I levels in the normal-weight group were 0.90 ng/L. Twelve months following weight loss surgery, cardiac troponin levels dropped to 1.30 ng/L in the surgical group (P<0.001), whereas the same marker of myocardial injury dropped very modestly, to 2.15 ng/L in the intensive lifestyle-intervention group.

Adjusted for age, gender, and baseline cardiac troponin I, among other variables, surgical treatment independently predicted a reduction in cardiac troponin I levels from baseline to 12 months of follow-up by an odds ratio of 2.32.

The Obesity-Troponin Connection

“Morbid obesity was most certainly a factor strongly contributing to the elevated levels of troponin I in this cohort,” according to Lyngbakken. “And [because] the surgery group had a greater weight loss than those treated conservatively, we believe that much of the reduction in troponin I [in the surgical group] can be attributed to a greater weight loss in this group.”

Serum triglycerides were also independently associated with troponin I reductions in the study, he said. After 12 months, reductions in triglycerides were twice as great: a median of 0.6 mmol/L in the surgery group compared with 0.3 mmol/L in the lifestyle-intervention group (P<0.001).

Although investigators could not say that there was a causal relationship between reductions in serum triglycerides and troponin I levels, Lyngbakken said, “we believe that weight reduction has a positive impact on the cardiometabolic milieu as reflected in reduced levels of serum triglycerides with subsequent reductions in levels of troponin I.”

Body-mass index is linearly associated with left ventricular mass in morbidly obese patients, the group observed. Thus, the reduction in cardiac troponin I levels seen following dramatic weight loss from bariatric surgery may reflect an unloading of the stressed heart and subsequent reduced cardiac mass, hemodynamic stress, and risk of heart failure.

Reference: Lyngbakken M, Omland T, Nordstrand N, et al. Effect of weight loss on subclinical myocardial injury: A clinical trial comparing gastric bypass surgery and intensive lifestyle intervention. Eur J Prev Cardiol 2015; DOI:10.1177/204748731561896. Abstract

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