Skip navigation

Patients with blocks in the coronary arteries can suffer from the following problems

  1. 1. Chest pain – Angina Pectoris, stable and unstable
  2. 2. Heart attack – Myocardial Infarction
  3. 3. Reduced pumping capacity of the heart – heart failure
  4. 4. Sudden death due to cardiac arrest

 

Today we shall talk about stable angina pectoris. The reason for this is during the last year and a half, a clinical trial (COURAGE), published in the New England Journal of Medicine has stirred up the debate on how to treat stable angina.

 

Patients with stable angina get chest discomfort or pain on walking, running or other physical exertion. Pain is typically absent with minimal effort or at rest. Patients with angina at rest or very minimal activity have unstable angina (USA). USA is a more serious condition and we shall talk about it another time.

 

When body is at rest the workload on the heart is low. During exertion the heart has to pump harder and to supply higher energy for this pumping function, heart demands increased blood flow through the coronary arteries. Typically stable angina is due to blocks in the coronary arteries that are serious enough to hamper increased blood flow during effort, yet allow normal blood flow during rest. Which explains why symptoms occur only during effort.

 

Such patients get relief of symptoms by one or more of following treatments:

  1. Anti-anginal medications: medical treatment (MT)
  2. Coronary angioplasty with or without stent placement (PCI)
  3. Coronary artery bypass grafting surgery (CABG)

 

Even when PCI or CABG is applied the basic medications will continue. So if I mean CABG, it actually means that CABG is added on to MT.

 

It is no rocket science to understand that for patients with milder degrees of the problem, MT suffices and for more serious angina, PCI & CABG may be additionally required. Which patients will require PCI & CABG will depend on a number of clinical parameters: so-called indications. For instance in patients who have left main coronary blocks or serious reduction of heart pumping function or with multiple blocks in all 3 coronary arteries CABG is indicated. This is because it has been proven by scientific studies that such patients are at risk of developing heart attack and/or dying if left on MT alone.

 

There is a problem in applying this seemingly simple treatment principle to PCI: hitherto no scientific study has shown that PCI, i.e., stents can prevent death or heart attacks in patients who have stable angina when compared to MT. which means that if angina is well controlled, MT alone is enough. And if risk of death or Myocardial infarction (MI) is perceived, one should proceed for CABG.

 

Where do stents come in into this equation?

 

When stents were introduced PCI was applied to patients who had serious blocks and needed surgery. PCI was more convenient to patients and less expensive than CABG. As experience with stents grew, more & more situations that hitherto required CABG were being addressed by PCI.

 

In situations like heart attack and unstable angina, PCI is certainly life saving. In many circumstances, an assumption was made that in stable angina too stents would be life saving. This may account for the fact that a larger number of patients with stable angina undergo PCI than CABG. Consider this: in USA 7% pts of angina undergo PCI as compared to 2% every year. This accounts for over 100,000 PCI procedures each year.

 

COURAGE trial

This clinical trial compared the effects of MT & PCI: it was meant to see if use of stents benefitted by preventing deaths or heart attacks in stable angina patients. In this study it was observed that when used early during the course of angina, stents do not prevent death or heart attacks more effectively than medicines alone do. Medical treatment alone was good enough to protect patients against death or heart attacks. However, two additional facts were observed:

1. Stents provided quicker and more effective relief from angina

2. Many patients, in fact nearly a third, who were put on MT alone at the outset ‘crossed over’ and underwent a PCI procedure midway.

 

What this tells is that some patients have angina severe enough to warrant PCI or even a CABG. But mere fact that someone has angina does not mean that stents have to be inserted. In a large majority of patients medications can be just as good.

 

Close analysis of COURAGE trial will show that there were methodological and statistical problems. Following the publication of the trial there has been a spate of articles both in the medical journals and regular press about the trial. 18 months after the trial, the debate rages as to whether the trial was appropriately conducted, whether the results of the trial are wrong, whether stents should be used at all for treating angina.

 

Doctors who argue for COURAGE say that stents have been overused for treatment of stable angina. They feel that needless PCI procedures on patients who can be treated with medicines, causes an economic burden and puts patients to risk of the procedure. In fact, pro-COURAGE activists feel that stents are being inserted because it financially benefits hospitals and doctors involved.

 

Doctors who argue against COURAGE say that a reasonable number of patients cannot be satisfactorily treated medicines alone, yet their condition does not warrant a CABG surgery. These patients benefit from stents, and in fact need them. These doctors feel that COURAGE, with all its methodological flaws, has needlessly cast aspersion on the interventional fraternity.

 

Nevertheless, looking at the mass of medical literature even other than COURAGE trial, the following conclusions can be made about stents in stable angina

  1. Stable angina is not as dangerous as heart attack or Unstable angina. Still, all stable angina patients do not end up with uniformly safe outcomes. Some patients are truly low risk patients who are unlikely to die or have heart attacks in the coming years. Some, however carry a real risk of death or heart attack
  2. Identification of low or high risk depends on clinical parameters: age, gender, smoking status, diabetes, previous heart attacks or heart surgery, severity of angina etc.
  3. In addition an echocardiogram can be used to calculate the pumping efficiency of the heart. If the pumping is low, risk is high.
  4. Most patients of stable angina should undergo a stress test: either a TMT or a stress thallium. These tests can identify patients at high risk for heart attack or death
  5. For patients with truly low risk medical treatment alone is fine. Rarely do such patients need to undergo angiography, PCI or CABG if well treated with medicines
  6. All patients who fall in the higher risk categories should undergo coronary angiography
  7. Based on the coronary angio report many of them will undergo CABG surgery
  8. A proportion of patients who have severe angina not well treated by medicines alone, but whose angiography does not suggest need for CABG, maybe treated with stents

 

COURAGE or no courage, it appears that stents will continue to be used for treatment of severe stable angina. Improvement in angina and quality of life is unquestionable with stents. Better conducted trials will definitely address whether stents save lives in stable angina setting. Until then one difference COURAGE has made is that, unnecessary use of stents for trivial angina has certainly been minimized.

 

 

 

Advertisements

One Comment

  1. nnn wen r wryting abt USA?i mean unstabl angina?.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: