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