Should Stable Angina Be Treated With Stenting or Medications?
One of the most controversial clinical trials of 2017 has doctors debating this question. Here, a leading cardiologist explains when stenting may be the better choice, and why.
If you have stable angina—meaning your chest pain occurs predictably with physical exertion and disappears with rest—your doctor may recommend a percutaneous coronary intervention (PCI, or balloon angioplasty and stenting) to relieve your symptoms.
But the result of a 2017 clinical trial called ORBITA has cardiologists worldwide reconsidering this advice. The trial, which compared a sham (“fake”) procedure to PCI in patients with stable angina after six weeks of optimal medical treatment, concluded that stenting was not significantly better than medications in helping patients exercise longer before angina began, nor did it lessen the severity of the chest pain. Consequently, some cardiologists have stopped recommending PCI for these patients. Other cardiologists, however, remain convinced that PCI is often the better choice. We asked Cleveland Clinic interventional cardiologist Samir Kapadia, MD, to explain his point of view and why he feels this clinical trial should not change the way stable angina is treated.
Q: Let’s start by talking about stable angina. Is it dangerous?
If the buildup of plaque in your arteries reaches 70 to 90 percent, blood flow will be obstructed enough to get chest pain with physical exertion. This is called stable angina, and it is not an emergency.
What you need to worry about is having stable angina that turns into unstable angina. If you have a blockage of 70 percent or more, and a blood clot forms on the surface of the plaque, blood flow can be further slowed or stopped. If the obstruction reaches 90 percent, you will experience angina at rest. This is unstable angina, and it is a medical emergency. If blood flow becomes 100 percent blocked, you will suffer a heart attack.
Q: If you have stable angina, will any procedure help you live longer?
No procedure has been shown to help people live longer. The chance of dying from stable angina is only 1 percent per year, and it’s hard to prove that a treatment will save lives if the condition is not life threatening. However, either PCI or coronary artery bypass grafting will improve blood flow and your ability to exercise without feeling chest pain.
Q: ORBITA concluded that PCI was as effective as optimal medical therapy. Please explain this.
Before ORBITA participants were randomized to PCI or the sham procedure; all were treated for six weeks with an aggressive medical regimen consisting of two antiplatelet therapies, two or more anti-angina medications, a beta-blocker, calcium-channel blocker and statin. It was so effective in eliminating angina that 30 of the 230 participants dropped out of the study before being randomized to PCI or the sham procedure.
Q: So why isn’t optimal medical therapy considered a better treatment than PCI for stable angina?
If a patient is sedentary or relatively inactive, aggressive medical therapy can be a reasonable choice. But many patients don’t want to take multiple medications and don’t want to be told they must take it easy. They also don’t want to worry about their angina becoming unstable and suffering a heart attack. If a large area of their heart is likely to be affected by a heart attack, which could be fatal, wouldn’t it be better to prevent the heart attack by opening the blockage? When a key artery is 70-80 percent blocked, revascularization with PCI is reasonable.
Q: How do you know the extent of a blockage?
Today, we use a fractional flow reserve (FFR), which measures blood pressure on both sides of a narrowing. If the difference from one side to the other is 20 percent or more during exercise, the blockage is significant. Studies have shown that in these cases, stenting is better than medical therapy.
Q: There’s a lot of talk that doctors will stop recommending PCI for stable angina as a result of the ORBITA trial. What do you think?
It is a terrible misinterpretation of this trial. The trial randomized only 105 patients to PCI and 95 to sham, which is too few to draw conclusions. When the researchers measured the blockages with FFR, they found that 30 percent of patients did not have a pressure difference of 20 percent. These patients did not have a blockage that restricted blood flow with exercise and, therefore, did not need a stent. However, these patients were not excluded. Why would we see a benefit if one-third of the patients didn’t even need the treatment?
The researchers set out to learn whether, after stenting, patients could exercise at maximum capacity 30 seconds longer than those who received a sham stent. In other words, they wondered if the effect of PCI was real or placebo. They found a statistically significant improvement in exercise tolerance in the patients who received stents. However, they put stents in patients who we would not stent today. When they compared those treated with stents to those treated with placebo, the results were contaminated by different treatments in the same group and having too few patients in the study. In a small study, what you do to the patients is more important than what you intend to do. They should have compared outcomes in patients who needed a stent with patients who did not need a stent.
Q: So what is the take-home message for patients with stable angina?
Medical therapy should be offered when appropriate, but it would be a disservice to tell active patients with chest pain to simply slow down, when restoring blood flow with PCI would allow them to be more physically active before angina begins. They also need to know that aggressive modification of risk factors will be necessary to prevent further progression of their disease.