Tag Archives: ischemia

ISCHEMIA Shows Medical Therapy Outcomes As Good As Coronary Stents or Bypass For Most CAD Patients

The ISCHEMIA (International Study of Comparative Health Effectiveness With Medical And Invasive Approaches) study presented at the AHA meeting this week provides further evidence that a conservative approach utilizing optimal medical therapy is an acceptable strategy for most patients with stable coronary disease (CAD).

Cardiologists have known for a decade (since the landmark COURAGE study) that outside the setting of an acute heart attack (acute coronary syndrome or ACS), coronary stents don’t save lives and that they don’t prevent heart attacks.

Current guidelines reflect this knowledge, and indicate that stents in stable patients with coronary artery disease should be placed only after a failure of  “guideline-directed medical therapy.”  Despite these recommendations, published in 2012, half of the thousands of stents implanted annually in the US continued to be employed in patients with either no symptoms or an inadequate trial of medical therapy.

Yes, lots of stents are placed in asymptomatic patients.  And lots of patients who have stents placed outside the setting of ACS are convinced that their stents saved their lives, prevented future heart attacks and “fixed” their coronary artery disease. It is very easy to make the case to the uneducated patient that a dramatic intervention to “cure” a blocked artery is going to be more beneficial than merely giving medications that stabilize atherosclerotic plaque, dilate the coronary artery or slow the heart’s pumping action to reduce myocardial oxygen demands.

Stent procedures are costly  in the US (average charge around $30,000, range $11,000 to $40,000) and there are significant risks including death, stroke and heart attack. After placement, patients must take powerful antiplatelet drugs which increase their risk of bleeding. There should be compelling reasons to place stents if we are not saving lives.

What Did ISCHEMIA Prove?

ISCHEMIA (paper unpublished but slides available here) showed that an invasive strategy (employing cardiac catheterization with resulting stenting or coronary bypass surgery (CABG)) offered no benefit over optimal medical therapy in preventing cardiovascular events in patients with moderate to severe CAD.

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Rates of all-cause death were nearly superimposable over the years studied, reaching 6.5% and 6.4% at 4 years for the invasive and conservative groups,

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Inclusions and exclusion criteria are listed below. Patients with unnaceptable angina despite optimal medical therapy were not included. These patients clearly benefit symptomatically from revascularization (as long as their chest pain is actually angina and not from another cause.)

All patients had stress imaging studies demonstrating moderate to severe amounts of ischemia. Such patients with very abnormal stress tests in the past have typically been sent immediately to the cath lab.

Based on ISCHEMIA we now know in these patients there is no need to do anything urgently other than institute OMT.

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These patients were on good medical therapy which likely explains the very good outcomes in both conservative and invasive arms. The “high level of medical therapy optimization” is what cardiologists should be shooting for with LDL<70, on a statin with systolic blood pressure <140 mm Hg, on an antiplatelet drugg and not smoking.

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Interestingly coronary CT angiography (CCTA) was utilized prior to patients receiving catheterization. I’ve been  utilizing this noninvasive method for visualizing the coronary arteries increasingly prior to committing to an invasive approach.

Quality Of Life 

Finally, in a separate presentation the ISCHEMIA trial showed that the invasive strategy did improve symptoms and quality of life modestly. It did not improve quality of life in those without angina symptoms.

The ORBITA study (which I wrote about here) showed that a large amount of the symptomatic improvement in patients following stenting may be a placebo effect.

Importance Of ISCHEMIA

Hopefully the results of ISCHEMIA will cut down on the number of unnecessary catheterizations, stents and bypass operations performed. This, in turn, will save our health system millions of dollars and prevent unnecessary complications.

Outside the setting of an acute heart attack the best approach to patients with blocked coronary arteries is a calm, thoughtful, and measured one which allows ample time for shared decision-making between informed patients and knowledgeable physicians. Such decisions should carefully consider the ISCHEMIA, COURAGE and ORBITA results.

Nonischemically Yours,

-ACP

N.B. Ischemia is a fantastic acronym for this study. Doctors use it a lot to describe the absence of sufficient blood flow to tissues.

N.B.2 Although I deplore the number of unnecessary caths and stents performed in the US, especially in patients without symptoms and those with noncardiac chest pain, I still utilize them in my patients with flow-limiting coronary stenoses and unacceptable anginal chest pain with symptoms despite optimal medical therapy and have noticed outstanding results. This angiogram shows a tight, eccentric LAD blockage in such a patient who now, post stent, has had complete resolution of the chest pain that limited him from even short walks.

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What is the Significance of a Borderline Stress Test and What Is The Value of a Coronary Calcium Score after a Stress Test?

A reader asks me the following question:

I’m 35 years old male and was positive for myocardial ischemia during stress test. The cardiologist said that my result was borderline. I’m not sure what does he meant by “borderline”. Also does it help if I do CAC score since my stress test already came out with positive MI?

Good questions.

First off, to understand what any stress test means we have to know the pre-test probability of disease. For example, in 35 year old males without chest pain the likelihood of any significantly blocked coronary artery is very low. This means that the vast majority of positive or borderline tests in this group are false positives, meaning the test is abnormal but there is no disease.

Even if we add exertional chest pain into the mix the probability of a tightly blocked coronary in a 35 year year old is incredibly low (but there are some congenital coronary anomalies that occur.)

The accuracy of stress tests varies depending on the type. The standard treadmill stress test with ECG monitoring is about 70% sensitive  and 70% specific. Adding on a nuclear imaging component improves the sensitivity (it makes it more likely we will pick up a blockage if it is present) to about 85% however, in the real world, the specificity (chance of a false positive) is still quite high. Accuracy varies a lot depending on how good the study is and how good the reader is.

Borderline for either the stress ECG the stress nuclear (or stress echo) means that the test wasn’t clearly abnormal but it wasn’t clearly normal. It is in a grey zone of uncertainty.

Given your low pre-test probability of disease it is highly likely your “borderline” test result is a false positive. Whether anything else needs to be done at this point depends on many factors (some from the stress test)  but most importantly, the nature of the symptoms that prompted the investigation in the first place.

If there are no symptoms and  you went for more than 9 minutes on the treadmill likely nothing needs to be done.

Would a coronary calcium scan add anything?

A very high score (>let’s say 100 for age 35) would raise substantial concerns that you have a coronary blockage.

A zero score would be expected in your age group and probably wouldn’t change recommendations .

A score of 1 up to let’s say 100  means you have a built up a lot more plaque than normal and should look at aggressive modification of risk factors but likely wouldn’t change other recommendations.

So the CAC might be helpful but most likely it would be a zero and not helpful.