STENTS VS. BYPASS SURGERY FOR CORONARY ARTERY DISEASE

 

Over the past 5 years or so, there has been a great deal of debate between experts regarding the optimal management of blocked coronary arteries in the heart.  Overall, cardiovascular disease remains the most common cause of death in most developed countries, with cancer coming in as the second most common cause of mortality (and, in some demographic groups, cancer has already surpassed cardiovascular disease as the most frequent cause of early death).  Relatively recent advances in the minimally invasive management of diseased coronary arteries have made it possible for millions of Americans to avoid coronary artery bypass graft (CABG) surgery.  Instead, clogged and narrowed coronary arteries can often be widened with “balloon angioplasty,” using specialized catheters that are threaded up to the heart from veins in the groin or arm.  Because “ballooned” coronary arteries rapidly begin to narrow again, most of the time, tiny scaffold-like meal stents are placed within the lumen of the re-expanded coronary arteries, helping to keep them open to the flow of heart-sustaining blood. 

 

Currently, the superiority of coronary artery stents vs. CABG surgery is the topic of enormous debate.  There is also great controversy regarding which type of coronary artery stents are the best to use.  Recent research studies have called into question the safety of at least some types of so-called drug-eluting stents, which are coated with drugs that inhibit re-growth of the lining of diseased coronary arteries and, theoretically anyway, help to keep these arteries open longer.  However, most of the recent clinical research studies have generally found coronary artery stents to be as effective as CABG surgery in restoring cardiac blood flow through narrowed coronary arteries in many patients, although the duration of this benefit appears to be shorter than that provided by CABG surgery, and the need for repeat interventions is much more common in patients receiving stents rather than surgery.  Whether or not stents provide similar long-term survival benefit as that obtained after CABG surgery has also been the topic of considerable debate, and conflicting research results, with some studies suggesting that, at least for blockages of the dominant coronary artery, the left main coronary artery, CABG surgery may indeed improve survival when compared to stents.  A new study, from Korea, and just published in the New England Journal of Medicine, therefore provides additional important information when comparing the outcomes of stents with those achieved by CABG surgery in patients with blockages of the left main coronary artery.

 

In this cohort study (which was not a prospective, randomized study), approximately 1100 stent patients and 1100 CABG surgery patients, all with “unprotected” left main coronary artery narrowing, were evaluated with respect to the post-treatment incidence of heart attack (myocardial infarction), stroke, need for repeat interventions to re-open recurrent narrowing of previously treated coronary arteries, and death.

 

Overall, there was no statistically significant difference in the risk of death between the patients that received stents and those that underwent CABG surgery.  When taken together as a composite outcome, there was also no overall significant difference in the incidence of heart attack or stroke between the two groups of patients.  However, as almost every previous similar study has shown, patients who received stents were nearly 5 times as likely to require subsequent interventions to clear and open re-clogged coronary arteries after stenting, when compared to the patients that had their narrowed coronary arteries completely bypassed by CABG surgery. 

 

Regarding the ongoing debate about the relative safety of “bare metal” stents versus “drug-eluting” stents, a trend towards an increased risk of death was observed in this study among patients who received drug-eluting stents (when compared to the patients who received bare metal stents), although this trend did not reach accepted levels of statistical significance.

 

The results of this study are generally consistent with previous studies, although its focus on left main coronary artery disease makes it somewhat unique.  Also, this study’s findings that patients receiving drug-eluting stents experienced a trend towards higher mortality than those who received bare metal stents may be cause for added concern, although experts in the field of coronary artery revascularization continue to debate each other regarding the adverse effects, if any, of drug-coated stents. 

 

Unfortunately, this clinical research trial does suffer from a few serious limitations.  First, and foremost, it was not a prospective, randomized clinical trial.  Therefore, it is subject to the same “selection biases” inherent in all non-randomized, non-prospective studies.  Secondly, the average duration of patient follow-up in this clinical trial was about 3 years, which is a relatively long time for research trials looking at coronary artery stents.  However, clinical studies involving CABG surgery frequently include patient follow-up durations of 5 or more years, and 10 years in some studies.  Whether or not the results achieved with coronary artery stents, as observed in this non-randomized, non-prospective clinical study, will remain stable for 5 years, or even 10 years, remains to be seen.  In my view, this clinical trial provides interesting and potentially useful clinical information, but because of these significant limitations, it is probably best viewed as an indication to proceed with a larger prospective, randomized clinical trial with long-term follow-up.  It will only be through such a clinical research trial that the results of this particular study can be definitively affirmed.

 

 

THE “DASH” HYPERTENSION DIET & CARDIOVASCULAR DISEASE PREVENTION

 

High blood pressure (hypertension), like diabetes, is often referred to as “the silent killer.”  Patients with hypertension are usually unaware of their elevated blood pressure, and of hypertension’s insidious adverse effects on vital organs throughout the body, including the brain, the heart and the kidneys.  Over time, untreated hypertension can cause serious, irreversible damage to these and other organs, resulting in an increased risk of stroke, heart attack, heart failure and kidney failure.  Multiple treatment approaches to hypertension have been advocated by experts, including diet, exercise, avoidance of obesity and, when necessary, the use of medications to lower elevated blood pressure.

 

The DASH diet (“Dietary Approaches to Stop Hypertension” diet) has been shown to be a valuable adjunct in the treatment of high blood pressure.  The DASH diet plan involves eating more fruits and vegetables, whole grain foods, fish, poultry, nuts and low-fat dairy products, as well as foods that are good sources of magnesium, potassium and calcium.  At the same time, the DASH diet calls for significantly decreasing dietary intake of red meat and other high-fat foods, sugary foods, and salt.  While previous studies of the DASH diet have shown it to be effective in helping to lower blood pressure, the effects of the DASH diet, if any, on reducing the risk of coronary artery disease and stroke is not well understood.  A new prospective study, from Harvard University and the American Cancer Society, and just published in the journal Archives of Internal Medicine, looks at the long-term impact of the DASH diet on the risk of coronary artery disease and stroke in otherwise healthy adult women.

 

In this study, the enormous Nurses’ Health Study, more than 88,000 female nurses, aged 33 to 59, were closely followed between 1980 and 2004.  At the time of entry into this landmark public health study of women, study volunteers had to be free of any clinical evidence of cardiovascular disease or diabetes.  During an average of 24 years of follow-up, dietary intake was assessed a total of 7 times.  Lifestyle and medical histories were also collected every other year.  Although the women participating in this huge prospective epidemiological study were not required to follow the DASH diet, a “DASH dietary score” was used to assess the diets of these nurses, based upon the specific recommendations contained within the DASH diet’s guidelines.

 

Among this very large cohort of study volunteers, 2,129 were diagnosed with a heart attack (myocardial infarction) during the course of this study, 976 women actually died from complications of coronary artery disease, and 3,105 women suffered a stroke.  When all of the women in this study were graded according to how closely their individual diets corresponded with the DASH diet’s guidelines, 5 levels of adherence (from very poor adherence to excellent adherence) were derived.  Using this “DASH diet score,” the researchers found that the women with the best adherence to the DASH diet guidelines, when compared to those with the worst adherence, experienced a 24% reduction in the relative risk of developing coronary artery disease and heart attack (both fatal and non-fatal heart attacks).  Similarly, patients who followed a “DASH-like” diet had an 18% reduction in the relative risk of stroke when compared to the women who did not follow DASH diet guidelines.  Interestingly, when blood tests for the inflammatory markers C-reactive protein and Interleukin-6 were measured, the women who followed DASH diet guidelines had significantly lower levels of these pro-inflammatory substances, which have been linked by other studies to an increased risk of coronary artery disease and cancer.

 

While the absolute level of risk reduction for coronary artery disease, heart attack (both fatal and non-fatal), and stroke observed with strict adherence to the DASH diet, in this study, were relatively small, these findings are still clinically significant.  This study specifically enrolled clinically healthy middle-aged women, and then followed them for more than two decades (at the time that this study was published).  Using their extensive health database on these nearly 90,000 women, the study’s authors statistically corrected their data for differences in age, smoking status and other known cardiovascular risk factors before reaching their conclusions, in an effort to isolate the effects of diet, alone, on cardiovascular illness and mortality rates.  Taken together, this study provides strong evidence that a healthy diet, along the guidelines established by the DASH diet, can, over time, reduce the risk of heart disease and stroke, even in already healthy adult women (and, presumably, men as well).  These apparent DASH diet benefits are, of course, additive to the known benefit of the DASH diet in reducing elevated blood pressure in hypertensive adults as well.  (As always, please remember to consult your physician before making any significant changes in your diet!)

 

 

TESTOSTERONE THERAPY FOR WOMEN WITH DECREASED SEXUAL DESIRE & FUNCTION

 

While an objective definition of decreased libido in women is generally lacking in most publications on the subject, by some estimates, more than 60% of women have been estimated to experience lowered levels of libido, or other forms of “sexual dysfunction,” by experts in the field of sexual health.  Various treatments, both pharmacological and behavioral, have been advocated for women who themselves perceive—or who are perceived by their partners—to have a decreased level of sexual desire or interest.  Testosterone, the sex hormone that appears to underlie interest in sexual behavior in both men and women, has increasingly been used to treat women with decreased libido (and men complaining of decreased desire too, for that matter).  Although normal blood levels of testosterone in women are much lower than in men, testosterone still appears to mediate libido in both sexes, and so interest in testosterone supplementation for women with decreased libido is a logical treatment to consider.  A new prospective, randomized, placebo-controlled, double-blinded study in the Annals of Internal Medicine, from Australia, adds to our understanding of at least the short-term risks and benefits of supplemental testosterone therapy in women with low testosterone levels who also experience decreased libido.

 

In this study, 261 women, aged 35 to 46, with documented low blood levels of testosterone and decreased libido, were randomized to receive one of 3 different doses of testosterone, or a placebo (an inactive substitute for testosterone), for a duration of 16 weeks.  An absorbable spray applied to the skin, on a daily basis, was used in each case, and neither the patient nor the person administering the spray knew if the spray contained testosterone or the placebo spray. 

 

In yet another demonstration of the “placebo effect,” the women in all treatment groups, including those receiving the inert placebo spray, reported a significant increase in satisfactory sexual events (as defined by the researchers conducting this study) during the course of this study.  However, women receiving the intermediate dose of testosterone spray reported the greatest increase in satisfactory sexual events (SEEs) when compared to the women who had, unknowingly, received the placebo spray (2.48 “SSEs” vs. 1.70 “SSEs” within a 28-day period, respectively, to be precise…).  Interestingly, the women receiving the highest dose of testosterone did not appear to derive any benefit, in terms of increased “SSEs,” when compared to women receiving the placebo spray. 

 

This interesting study suggests that, for premenopausal middle-aged women reporting low sexual desire, at least among those with documented low blood levels of testosterone, a daily 90 microliter spray of absorbable testosterone on the skin can significantly improve sexual interest and satisfaction, while both lower and higher doses of transdermal testosterone appear to be less effective.  At the same time, this study also confirms what is already well known about human sexual behavior, and that is the fact that the most important sexual organ is the brain.  All of the women in this placebo-controlled double-blinded study reported improved sexual interest and function after enrolling in this clinical research trial, including the women who only received (unknown to them) an inert placebo spray. 

 

Unfortunately, while there were no apparent significant side effects associated with transdermal testosterone supplementation in this 16-week research trial (except for the manageable tendency to develop increased hair growth at the application site), this study did not continue long enough to assess for long-term side effects (nor did the researchers measure the effects of testosterone supplementation on blood cholesterol levels or cardiovascular function, both of which are directly affected by testosterone).  The authors are to be congratulated, however, on their use of a stringent prospective, randomized, double-blinded, placebo-controlled design for their research trial, which provides clinical research data of the highest attainable objectivity and quality.  The next step, it would be appear, is to repeat this clinical trial with larger numbers of patients, and to follow them longer, and in more detail, in order to fully assess the risks and benefits associated with chronic transdermal testosterone supplementation in women with low serum testosterone levels who simultaneously report diminished libido and sexual function.

 

 

Dr. Wascher is an oncologic surgeon, professor of surgery, a widely published author, and the Director of the Division of Surgical Oncology at Newark Beth Israel Medical Center:

http://www.sbhcs.com/hospitals/newark_beth_israel/mservices/oncology/surgical.html

Send your feedback to Dr. Wascher at:  rwascher@doctorwascher.net
 

http://www.doctorwascher.com

Copyright 2008.  Robert A. Wascher, MD, FACS.  

All rights reserved.

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