Arya M. Sharma, MD

This week the American Heart Association released a Scientific Statement on Bariatric Surgery and Cardiovascular Risk Factors in the latest issue of CIRCULATION.

Interestingly, the lead author and chair of the very distinguished panel of authors is our very own Paul Poirier from Laval University, Quebec City, Canada.

As the Statement points out:

“It is becoming clear that the pathophysiology of obesity is more complex than simply overeating and not exercising. In studies of bariatric surgery patients, appetite control and satiety appear to be key mechanisms for weight loss in gastric banding and gastric bypass patients, whereas calorie malabsorption plays a role in weight loss maintenance in the intestinal bypass operations.

All operations have advantages and disadvantages, with no clear evidence of one being the standard of care. There are currently no large-scale head-to head randomized trials comparing surgical procedures. Restrictive operations have a lower mortality with a lower rate of surgical and nutritional complications compared with the malabsorptive or combination operations. However, on average, restrictive operations require more frequent postoperative outpatient visits and are associated with a slower and lesser weight loss.”

The Statement provides a comprehensive and very balanced overview of the effects of bariatric surgery on cardiovascular risk factors including diabetes mellitus, hypertension, dyslipidemia, fatty liver disease, and sleep apnea and also discusses the proven benefit on cardiac morphology and function. Most importantly, the statement highlights the increasing evidence that bariatric surgery very significantly reduces the risks of dying from cardiovascular and non-cardiovascular complications of severe obesity.

The Statement also provides an overview of indications, caveats, complications and nutritional issues relevant to the care of these patients.

Relative contraindications to surgery include severe heart failure, end-stage lung disease, active malignancy, cirrhosis with portal hypertension, uncontrolled drug or alcohol dependency, and impaired intellectual capacity to understand and comply with the recommended lifestyle changes following surgery.

Finally, the statement also highlights a number of areas which require further research including a gaining better understanding of the neuroendrocrine mechanisms involved in the increased satiety, reduced hunger and metabolic changes associated with the different types of surgery as well as their impact on specific cardiovascular problems like peripheral vascular disease, strokes and malignant arrhythmias.

Thus, while the AHA statement clearly recognises the importance of bariatric surgery as a largely safe and effective treatment for patients with severe obesity, it also clearly defines the many areas in which further research needs to be conducted to better understand the mechanisms, long-term consequences, and outcomes with regard to improving cardiovascular health.

AMS
Edmonton, Alberta

Poirier P, Cornier MA, Mazzone T, Stiles S, Cummings S, Klein S, McCullough PA, Ren Fielding C, Franklin BA, & on behalf of the American Heart Association Obesity Committee of the Council on Nutrition, Physical Activity, and Metabolism (2011). Bariatric Surgery and Cardiovascular Risk Factors: A Scientific Statement From the American Heart Association. Circulation PMID: 21403092

I am currently attending the 2010 Scientific Meeting of the European Society of Cardiology, here in Stockholm.

In a session on diabetes and heart disease, Mamas Mamas from the University of Manchester, UK, reported that abnormal glucose tolerance (pre-diabetes or diabetes) is found in about 50% of unselected heart failure patients.

Importantly, only a small fraction of patients will have abnormal fastng glucose, suggesting that glucose tolerance tests are essential to determine abnormal glucose disposition in patients with heart disease.

Insulin resistance, in part due to decreased exercise capacity, may also be exacerbated in heart failure patients.

Longitudinal studies confirm the negative prognostic relevance of abnormal glucose tolerance in with a 35% increased risk in cardiovascular death with each 1% increase in HbA1c levels.

However, Mamas also noted that while the Diabetes Prevention Program, showed a marked reduction in the progression to diabetes with lifesyle intervention in individuals with pre-diabetes, the findings from this study did not suggest any reduction in heart failure or cardiovascular deaths.

Indeed, despite the wide recognition that diabetes is an important risk factor for heart disease, data on the prevention or improvement in cardiac function with diabetes treatment remains rather disappointing.

On a similar note, Clyde Yancy, Baylor University Medical Center, Dallas, TX, spoke on the issue of diabetic cardiomyopathy.

As Yancy pointed out, diabetic cardiomyopathy defined as significantly impaired cardiac function in diabetic patients in the absence of epicardial vascular disease, left-ventricular hypertrophy, valvular disease, or other causes of cardiomyopathy, makes it largely a diagnosis of exclusion.

The association between diabetic cardiomyopathy and diabetic retinopathy suggests that microvascular abnormalities may play a role.

However, there may also be direct metabolic effects of dysglycemia and hyperinsulinemia, resulting in lipotoxicity and generation of oxidative stress leading to apoptosis and fibrosis. This may well explain the findings of left-ventricular remodeling, myocardial fibrosis, collagen and lipid deposition with altered compliance and diastolic dysfunction, seen in patients with diabetic cardiomyopathy.

Animal studies show that increased glucose levels can increase expression of box-1 protein, involved in pro-inflammatory defense mechanisms. Blocking this response may, thus, prove a novel approach to preventing and treating cardiomyopathy.

This is important because, as noted previously by Mamas (and other speakers in this session), current anti-diabetic treatments do not appear to have the expected beneficial effects on heart function or macrovascular disease in patients with diabetes.

In the context of obesity management it is therefore perhaps important to recall the fact that one of the most impressive findings from bariatric surgery studies, is the remarkable reduction (upto 80%) of diabetes related mortality - something conventional diabetes treatments have yet to demonstrate.

Whether similar benefits can be seen with more moderate weight loss of course remains to be seen, nevertheless, it is certainly increasingly apparent that simply controlling blood glucose levels in patients with diabetes may not be the answer.

AMS,
Stockholm, Sweden

Eating more fruit and vegetables is a common recommendation in dietary guidelines to prevent everything from obesity and heart disease to premature aging and cancer.

In this context, berries are of particular interest, as they are particularly rich in anti-oxidants and a variety of phytochemicals like polyphenols, anthocyanins, proanthocyanidins, resveratrol, flavonols, and tannins that have demonstrated beneficial effects in vitro and in vivo studies.

But randomised controlled studies on the health effects of eating berries remain scarce.

It is therefore of interest that Arpita Basu and colleagues from Oklahama State University, in a paper just published in the the Journal of Nutrition, now report the results of a randomised controlled trial of blueberries in men and women with obesity and the metabolic syndrome.

In this study, the researchers examined the effects of eight weeks of daily blueberry supplementation (50 g freeze-dried blueberries, approximately 350 g fresh blueberries) compared to equivalent amounts of fluids in 48 participants with an average BMI of around 38 kg/m2).

While blueberries did not appear to have any effect on serum glucose or lipid profiles, there was a significant decrease in systolic and diastolic blood pressures (-6 and -4%, respectively) versus controls (-1.5 and -1.2%).

There was also a roughly 30% decrease in plasma levels of oxidized LDL in the blueberry group compared to a 9% reduction in controls.

No change in weight was reported.

Although this is a short-term study of only eight weeks duration, the data does suggest that there may be beneficial effects of regular consumption of blueberries on cardiovascular risk factors. Whether or not these effects translate into better health outcomes in the long term remains to be seen.

AMS
Edmonton, Alberta

Click here for additional posts and comments on my FaceBook page

Basu A, Du M, Leyva MJ, Sanchez K, Betts NM, Wu M, Aston CE, & Lyons TJ (2010). Blueberries Decrease Cardiovascular Risk Factors in Obese Men and Women with Metabolic Syndrome. The Journal of nutrition PMID: 20660279

We’ve long known that poor physical fitness and lack of exercise are important risk factors for heart disease.

But matters may be worse, because even for people who exercise regularly, sitting around most of the day may still be an important risk factor for dying of heart problems.

This important impact of sitting around (especially during leisure time) on cardiovascular mortality is reported in a paper by Alpa Patel from the American Cancer Foundation and colleagues just published in the American Journal of Epidemiology.

The researchers analysed data from a large prospective study of US adults enrolled by the American Cancer Society that included 53,440 men and 69,776 women who were disease free at enrollment.

After adjustment for smoking, body mass index, and other factors, time spent sitting (more than 6 vs. less than 3 hours/day) was associated with a 34% mortality risk in women and a 17% higher risk in men of dying during the 14-year observation period.

When both sitting for more than 6 hours/day and low physical activity were combined, mortality risk was around two-fold higher in both men and women compared to those with the least time sitting and the most activity.

The fact that time spent sitting was independently associated with total mortality, regardless of physical activity level, suggests that it is not enough to simply be active, but to also reduce leisure time spent sitting.

The study, obviously does not reveal what it is about sitting that increases risk. One aspect could be that simply standing is in fact a mild form of exercise. Not only, does standing stimulate the cardiovascular system to maintain blood pressure, but standing is also a form of resistance exercise - after all in order to stand, your muscles have to bear and support the entire weight of your body.

Thus, simply standing (rather than sitting or lying down) may provide an important positive stimulus to both the cardiovascular and musculoskeletal system that may well translate into lower risk.

Clearly, if exercise is not your thing, at least look for a job or hobby that keeps you on your feet.

AMS
Edmonton, Alberta

Click here for additional posts and comments on my FaceBook page

Patel AV, Bernstein L, Deka A, Feigelson HS, Campbell PT, Gapstur SM, Colditz GA, & Thun MJ (2010). Leisure Time Spent Sitting in Relation to Total Mortality in a Prospective Cohort of US Adults. American journal of epidemiology PMID: 20650954

Although excess weight is well known to substantially increase the risk for heart disease, we and others have consistently reported that obese patients with heart failure actually live longer than those who are normal weight or skinny.

This obesity “paradox” obviously begs the question of whether or not weight loss is something that you would actually recommend to someone who is obese and has heart failure - if being obese when you have heart failure, wouldn’t losing weight make things worse?

Believe or not, there are almost no studies addressing the impact of intentional weight loss on heart function. The few available studies are largely limited to small series of patients who underwent bariatric surgery, where weight loss does show marked improvements in heart function.

But can similar effects be achieved with dietary weight loss?

This is exactly the question that will be addressed by a study to be performed in collaboration with researchers at the Mazankowski Alberta Heart Institute. The study will include twenty severely obese individuals with heart failure, who will undergo intentional weight loss using a standardized low calorie diet (OPTIFAST 900). Their cardiac function and other parameters will be carefully measured and will hopefully show significant improvements in hemodynamic function and exercise capacity.

The study is funded with a $250,000 grant provided by the Alberta University Hospital Foundation and is due to be completed within three years (if not sooner).

To watch a video on this study as reported on CTV News click here or to read more about the background on CBC News click here.

AMS
Edmonton, Alberta