Category: Angiogram

4 Studies Proving Ordinary Angiograms Are Inaccurate

Inaccuracy in Angiograms has led to unnecessary Angioplasty and Bypass Surgeries. The inaccuracy lies not in the method but in the interpretation by doctors. It’s hard to believe that the same doctor can interpret Angiograms differently when images are shown at different dates.

Here are 4 studies brining the inaccuracy of Angiogram to lime light:

1.Interobserver Variability in Coronary Angiography:

4 Experts from Massachusetts General Hospital were shown 20 high quality Angiograms. And the end result was astonishing. Every expert had disagreement in some case or the other. The worst case scenario was in which an interpretation of 100% blocked artery by one expert was interpreted as 0% blocked by the other. It is also of importance to note that these 4 experts had each read more than 1500 Angiograms and taught other training professionals.

Source: http://circ.ahajournals.org/content/53/4/627.full.pdf

2.Discrepancy in Angiogram and Autopsy Findings

28 people who died during coronary operation were used for this study. These patients had an Angiogram in less than 30 days. Therefore, the amount of blockage presented through Angiogram and after Autopsy was considered. In five cases it was impossible to compare. Out of the 23 cases, 9 cases saw difference in blockage to be greater than or equal to 25%.

Source: http://circ.ahajournals.org/content/49/4/703.full.pdf

3.Comparison of Angiography and Autopsy Findings

After the passing of 10 people with severe Coronary Artery Disease an autopsy was done to find difference in blockage.

  • The autopsy showed 8 narrowed arteries between 51% and 75% blockage. But 7 of these arteries were underestimated by Angiograms.
  • 42 narrowed arteries with 75% to 100% blockage was found during autopsy for which 17 arteries were underestimated by Angiogram.

Source: http://annals.org/article.aspx?articleid=693322

4.Does Visual Interpretation of Angiogram determine Blockage Physiologically

Blockages in 44 vessels of 39 patients while on the operation table was studied with a doppler technique. It was found that Angiogram underestimated and overestimated blockages which were less than 60% percent. The study concluded stating that Angiograms cannot be used to determine the blockages level accurately.

Source: http://www.nejm.org/doi/full/10.1056/NEJM198403293101304

On 9 June 2013, the DailyMail ran an article which stated that 25% of time Angiograms are flawed. A cardiologist named Nick Curzen found in his trial that 26% percent received wrong treatment based on flawed Angiograms.

Here is a link to the news article on Dailymail.co.uk

What to Do? How Can One Increase Angiogram’s Accuracy?

ffr-catheter

Fortunately, the accuracy of Angiograms can be increased using Fractional Flow Reserve (FFR). FFR measures whether the blocked area shown in an Angiogram has significant blood flow.

The procedure involved in FFR is similar to Angiogram. Only addition is that blood pressure and blood flow is measured at the very area where blockage can be seen.

If measurement of blood flow and pressure is normal then there is no point in using a stent (as it won’t make any difference).

If the FFR value is less than 0.75 or 0.80 then physical intervention like stents will be used.

Recently, Instant wave-Free Ratio (iFR) has gained acceptance. iFR measures flow pressure and the deficit caused by blockage.

FFR required injection of adenosine which made patients uncomfortable. iFR does not require any injection making it cost effective and comfortable for the patients. The procedure is also faster than FFR.

Importantly iFR is used to determine immediately whether the stent has made any significant improvement to blood flow.

What Should You Do After an Angiogram?

Usually, its best if your cardiologist uses Fractional Flow Reserve or Instant wave-Free Ratio along with Angiogram. If you are planning for Angiogram try looking for labs equipped with FFR or iFR.

If you can’t find a lab equipped with FFR or iFR and your Angiogram shows blockages get a second opinion or if possible even a third.

Note: If blockages shown on an ordinary angiogram are severe and you need intervention immediately then your best bet is to listen to your cardiologist. 

featured image credit: harmelphoto.com

How a Coronary Angiogram is Performed and When?

In layman term, Angiogram is X-ray imaging of blood vessels.

Blood vessels don’t show up in X-rays. Hence, an Angiogram is required to look at blood vessels.

An Angiogram can be performed in any region. However, it is mostly associated with heart.

When Coronary Angiogram is Recommended?

When you have an episode of Angina or heart attack, Angiogram is recommended. Angiogram helps your cardiologist to find blocked coronary arteries. If any of the block(s), commonly called plaque or atherosclerosis, is more than 75% of blood vessel, a surgery is recommended.

How it is Performed?

Procedure is performed on an X-ray table. Since, the table will tilt during X-ray imaging, your legs and arms may be fastened to safety straps.

Blood pressure cuff to monitor your BP, Electrodes on your chest to monitor your heart rate and an oximeter to measure amount of oxygen in your blood are attached.

You will be given anticoagulant medication so that blood does not clot on catheter.

Local anesthetic is used for adults while for children general anesthetic is used.

Note: Local anesthetic numbs a certain area of body while general anesthetic creates a state of unconsciousness.

An incision is made on your arm or groin. Through this incision, a catheter is passed up to your coronary artery (just above your heart). A contrasting material (called dye) is injected.

When the dye passes through coronary arteries X-ray images are taken from various angles.

Comparing amount of blood flow in the arteries (using X-ray images), your cardiologist will find blocked area. A closer examination will reveal blocked percentage in your coronary artery.

As stated earlier, if more than 75% of artery is blocked, a surgery is recommended. It can be either angioplasty or bypass surgery.

What are the Risks Involved?

  1. You might be allergic to dye. Usually its rash or itching sensation. Before angiogram is taken tell your doctor if you are allergic to Iodine.
  2. The incision part may bleed.
  3. If you have kidney problems chances of iodine dye damaging your kidney are high.

After Angiogram is Done:

For 10 days or more the incision area will remain sore. It will take around 4 weeks for the incision area to resolve completely.

After 24 hours of Angiogram you can regain normal activity (unless you are advised to rest).