Bariatric Surgery Decreases Cardiovacular Risk Factors

Obesity—the Risk Factor for Cardiovascular Disease
The rapid increase in obesity seen over the last decade is a serious public health concern. The strong association of obesity with cardiovascular risk factors, such as high blood pressure, high cholesterol and diabetes, is well known. These modifiable risk factors independently increase the chance of developing coronary artery disease, a heart attack, stroke or peripheral vascular disease. About 70 percent of all diagnosed cases of heart disease are related to obesity, especially central or abdominal. Mortality due to cardiovascular disease is significantly higher in those with severe obesity. The overall risk of premature death from cardiovascular disease is increased fivefold in obese patients [1]. Risk of heart failure increases with excess weight: for each increment of 1 kg/m2 in body mass index (BMI), there is a 5 percent increase in the risk of heart failure for men, and 7 percent for women [2].

Obesity can lead to a heart failure due to a variety of changes occurring in obese individuals. Increased blood volume, fluid retention, and greater cardiac workload raise the risk of left ventricular enlargement and hypertrophy and, in consequence, heart failure and arrhythmias. Also, various hormones (i.e. Leptin) produced from excessive adipose tissue activate inflammatory systems, accelerating coronary atherosclerosis and directly damaging heart cells (atherosclerosis is 10 times more common in obese people compared to people of normal weight). Blood clots also can form in narrowed arteries to the brain and cause a stroke.

Lifestyle modifications, especially diet and physical activity, along with medications, are known to control cardiovascular risk factors. It is especially important for obese patients who smoke to find a means to quit, as their cardiac risk often is escalated beyond that of a non-obese patient.

Metabolic Syndrome and Diabetes
Metabolic syndrome, commonly seen in obese patients, is the coexistence of central (abdominal) obesity, high serum triglyceride levels, low serum high-density lipoprotein (HDL)-cholesterol levels, hypertension, sleep apnea and elevated fasting blood glucose level. Each aspect of metabolic syndrome increases the risk of developing coronary artery disease, heart failure and arrhythmia, and is very difficult to treat in the presence of obesity [5]. Metabolic syndrome often precedes the development of frank diabetes, a potent risk factor for cardiovascular disease. In many patients with metabolic syndrome, weight loss prevents the progression to diabetes. There is some evidence to suggest that bariatric surgery can improve glycemic control in patients who have diabetes.

Hypertension and Obesity
Hypertension raises the risk of heart attack, stroke, congestive heart failure and kidney failure. Over time, elevated blood pressure leads to left ventricular hypertrophy and heart failure. Elevated blood pressure is more often seen in obese patients. There is a threefold increased chance of having hypertension in obesity [6]. Reduction of body weight by 1 percent results in decreasing systolic blood pressure by 1 mm Hg and diastolic by 2 mm Hg [7]. Approximately 80 percent of patients undergoing gastric bypass surgery for obesity significantly improve or are completely cured from hypertension [8].

Sleep Apnea
Obesity predisposes a patient to sleep apnea. Recent evidence points to sleep apnea as a risk factor for hypertension, arrhythmia and heart failure. Weight loss achieved by bariatric procedures improves obstructive sleep apnea to the point of eliminating the need for continuous positive airway pressure. These findings were confirmed by a meta-analysis of all bariatric surgical procedures: complete resolution or significant improvement in obstructive sleep apnea was found in 83.6 percent of patients [8].

Effect of Weight-Loss Surgery on Cardiovascular Risk
The American College of Cardiology and American Heart Association indicated that weight-loss plays a key role in the prevention of heart disease, as well as for those who have already suffered a cardiac event. The largest prospective study, the Swedish Obesity Study (SOS), has shown significant improvements in all studied cardiovascular risk factors (i.e., hypertriglyceridemia, low HDL cholesterol, diabetes, hypertension and hyperuricemia) with a decreased usage of medications, amongst patients treated with bariatric procedures [9].

Bariatric surgery induces a profound and sustained weight-loss. Gastric bypass is known to achieve long-term and significant weight loss (> 50 percent of excess body weight) in 90 percent of patients [10]. This leads to decreased cardiac metabolic demand and blood volume. Consequently, blood pressure decreases, and the cardiac workload is likely to be reduced. Thus, weight-loss surgery can reduce the progression and promote regression of heart failure, ventricular hypertrophy and size. Ventricular function can be improved, significantly decreasing cardiac risk and medication requirements in 80 to 90 percent of patients [11]. Several studies showed decreased heart rate and improved cardiac output [12]. Substantial weight loss produced by bariatric surgery appears to reverse many of the electrocardiographic abnormalities associated with morbid obesity with arrhythmias typically improved with¬in few months after surgery [13]. Weight reduction, even when achieved by diet, has been shown to improve left-ventricular diastolic filling and ejection fraction [14]. Most patients with congestive heart failure symptoms show improvement within one to two weeks of surgery [11].

Weight loss produced by bariatric surgery reverses enlargement and improves elasticity of the aorta and major arteries [15]. Weight loss of around 10 percent of initial body weight improves endothelial function and procoagulant states [16]. Weight-loss surgery in morbidly obese individuals produces significant decreases in concentrations of inflammatory indicators (C-reactive protein and interleukin-6). QTc duration is shortened effectively and the prevalence of left-ventricular hypertrophy is decreased [3].

There is a notable improvement of atherosclerosis in obese patients following bariatric surgery. It leads to decreasing chances of developing major coronary events (chest pain, heart attack or pulmonary edema) more than five years following bariatric surgery [4]. The overall mortality due to cardiovascular diseases is reduced more than 70 percent following bariatric surgery [17].

The anatomic changes that are a consequence of surgery do not affect the absorption of cardiac medications, thus the efficacy of pharmacologic treatment is unaltered in patients who still require medications.

Bariatric Surgery and Cardiovascular Risk
Gastric bypass and other bariatric operations can be safely per¬formed in obese patients with pre-existing cardiac disease. In a recently published study, no difference in mortality in patients with coronary artery disease undergoing bariatric surgery was found when compared to those free from this disease [18]. Patients should be carefully managed preoperatively by a multidisciplinary team, including cardiology and internal medicine. Weight loss achieved by these patients is very similar to patients without heart problems: on average 60 percent reduction of excess weight loss (EWL) with significant improvement of risk factors leading to cardiovascular disease.

Tomasz Rogula, MD, PhD, is a staff surgeon at the Cleveland Clinic Bariatric and Metabolic Institute. He has trained in weight loss surgery in the United States, Italy and France. In addition to bariatric surgery, his specialty interests include laparoscopic and robotic surgery, gastrointestinal surgery and hernia repair. Dr. Rogula has done multiple pioneering research studies on novel weight loss surgery procedures and published multiple articles and book chapters on bariatric and laparoscopic surgery.

Deepak Bhatt, MD, FACC, FSCAI, FESC, FACP is the Director of the Interventional Cardiology Fellowship and the Associate Director for the Cardiovascular Medicine Fellowship at the Cleveland Clinic Foundation. Dr Bhatt obtained his undergraduate degree from the Massachusetts Institute of Technology, while also serving as a research associate at Harvard Medical School. He received his medical doctorate from Cornell University. His cardiovascular training was completed at the Cleveland Clinic Foundation. At the Cleveland Clinic, he is currently on staff as an interventional cardiologist. Dr Bhatt’s research interests include the study of oral and intravenous antithrombotic medications, as well as the optimal management of patients with acute coronary syndromes, including myocardial infarction. He also has research interests in advanced techniques for cardiac, cerebral, and peripheral intervention. He has written numerous book chapters on these topics and has published several articles in such journals as the JAMA, Nature Reviews, and American Journal of Medicine.

Philip Schauer, MD, FACS, is the Director of Advanced Laparoscopic and Bariatric Surgery at Cleveland Clinic and former president of the American Society for Metabolic and Bariatric Surgery. In addition to bariatric surgery, his specialty interests include laparoscopic surgery, gastrointestinal surgery and colon surgery. A frequent national and international lecturer, Dr. Schauer also has published scores of articles on topics relating to bariatric and laparoscopic surgery, and his first textbook on this subject is due out in 2007, entitled, Minimally Invasive Bariatric Surgery.

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