Here’s the Scoop on Whether to Take Low Dose Aspirin for Heart Disease
Here’s the Scoop on Whether to Take Low Dose Aspirin for Heart Disease
The ever-changing guidelines can be confusing not only to the layperson but also to cardiologists.
One of the most common questions I was asked as a cardiologist was, “Should I take aspirin?” I used to think the question was easy; however, the answer has become muddied with time. Because of its effect on platelets (blood cell component that makes blood more or less “sticky”), low dosages of aspirin (LDA) have long been known to help prevent blood clots. And it’s blood clots that may cause heart attacks, strokes, and sudden cardiac death. However, before diving into the data, let me share some personal history.
Because I have high blood cholesterol and a family history of early heart disease, I took low-dose aspirin (81–162 mg per day) for many years. However, in 2011, I had severe chest pain, prompting a visit to the emergency room. I thought I was having a heart attack. However, my EKG and blood enzyme tests were negative, ruling out that diagnosis. Out of an abundance of caution, I was admitted to the hospital for observation.
I already had normal stress tests in my office over the years. After conferring with one of my partners, I agreed to undergo cardiac catheterization the following day. Cardiac catheterization was the “gold standard” for diagnosing coronary artery disease. So much to my surprise, my coronary arteries were normal, ruling out significant coronary artery disease, or “hardening of the arteries.” Subsequent investigations found I had a large stomach ulcer due to my use of ibuprofen and steroids for other medical problems, and that was the cause of my chest pain. From that point forward, I stopped my aspirin.
Fast forward five years, and I was diagnosed with Crohn’s colitis, a form of inflammatory bowel disease (IBD). Last month, having failed medical treatment, I had surgery, and before the operation, I saw one of my partners for “surgical clearance.” I passed another stress test, so I was “cleared” for surgery from a heart standpoint. However, my former partner noted that people with IBD have higher than normal rates of heart disease, and being 73 and at-risk, I resumed low-dose aspirin.
Types of Prevention:
When discussing “heart disease prevention,” there are two different kinds. The first is called Primary Prevention. This type of prevention means the patient has no findings to suggest the presence of heart disease. However, as was my case, there are one or more “risk factors” to make them susceptible in the future to heart events, like angina, heart attack, or strokes. These factors include age, male gender, high cholesterol, high blood pressure, diabetes, smoking, and, in my case, inflammatory bowel disease.
The second type is called Secondary Prevention, for patients who have already had a cardiac event. The goal is to “prevent” more episodes in the future.
The idea that LDA could be useful in preventing heart disease is not new. Dr. Lawrence Craven first proposed it over 100 years ago. “Dr. Craven worked as a general practitioner at the Glendale Memorial Hospital in California and was fascinated by the etiology (casue) of MI (heart attack). Noting an increased risk of bleeding in patients’gums who received aspirin for pain relief after tonsillectomy, Craven hypothesized that aspirin’s antithrombotic (anti-clotting) properties would be beneficial for preventing MI.” He conducted clinical trials in men aged 45–65 with results showing reduced heart events in those patients who took aspirin. As shown in the following table, multiple subsequent studies confirmed his results.
The limitations of Craven’s study were it only included males, the age cutoff of 65 is young by today’s standards, and aspirin dosages were different. Individual risk factors were unknown at that time. The other studies noted above shared similar problems. However, severe bleeding episodes (like the GI tract or brain) appeared only mildly increased, so most doctors urged patients to take LDA.
Then, a study from Japan in 2008 looked at the ability of LDA to prevent heart events in patients without heart disease but who had diabetes. The study design was good and was double-blind (meaning investigators and patients did not know if they were taking aspirin or a placebo pill) and was randomized, and the ages were 30–85. Unfortunately, the results might have been tainted since 10% of the aspirin group stopped it due to side effects. And there were more serious bleeding episodes, some of which required blood transfusions in the aspirin group than the placebo group.
The study concluded, “In summary, in the JPAD trial, the first prospectively designed trial to evaluate low-dose aspirin in patients with type 2 diabetes without previous cardiovascular disease, low-dose aspirin as primary prevention did not reduce the risk of cardiovascular events.”
Unfortunately, over the last decade, more trials have done little to clarify the potential benefits vs. risks in the primary prevention of heart disease. The answer remains far from settled.
The same, however, cannot be stated for the secondary prevention of heart disease. In this case, repeated studies confirm the benefits of LDA consistently outweigh the risks of bleeding. However, with the addition of stronger platelet inhibiting drugs combined with LDA, even this is being reassessed.
Conclusions:
The great thing about studying older drugs over many decades is it allows us to gather more data and study the good and bad effects of a given drug on disease over a long period. And aspirin is a drug. The negative side of many decades is that science and medicine are not static. Newer drugs become available to supplement and or replace aspirin’s effectiveness in preventing blood clots and adverse cardiac events, which tends to muddy the picture.
At least in secondary prevention, LDA still appears to be a good cornerstone of therapy unless contraindicated by prior allergy, intolerance, or history of serious bleeding. But newer antiplatelet drugs are causing this standard practice to be re-evaluated. With primary prevention, the data is less clear. Therefore, before embarking on a lifelong course of LDA therapy, you should seek counsel with a cardiologist who can individualize your risks and benefits.