Top 5 Things About Myocardial Infarction Electrocardiogram, Here They Are!

Top 5 Things About Myocardial Infarction Electrocardiogram, Here They Are!

The term myocardial infarction refers to a heart attack. It occurs due to certain heart tissues or muscles not receiving sufficient blood and many professionals simply refer to the condition as MI. This can happen due to blockages that are in turn responsible for the blood deprivation. When the condition is left unaddressed, irreversible damage to the heart can take root, putting the patient in critical danger. It is for this reason that today we discuss the top five things to know about MI electrocardiograms. This will help patients understand their ECG diagnosis better while giving cardiologists an extra hand to help identify MI faster and hopefully save a life.

A myocardial infarction electrocardiogram can pick out silent heart attacks 

Learning how to pick out a myocardial infarction on an ECG is one of the most important skill sets that any ECG technician should have. That’s largely because many times patients can experience a heart attack and still be none the wiser. In fact, studies today indicate that up to 45 in 100 people globally experience silent heart attacks. These come with few to no symptoms, and risk factors include: 

• Physical inactivity 
• High blood pressure
• Genetics 
• Diabetes and more

These types of heart attacks often go by the sobriquet SMI or silent myocardial infarction. The only accurate diagnosis options available today involve ECG and other imaging tests. 

A myocardial infarction ECG is a surefire way to detect heart attacks. It offers a much higher diagnostic yield compared to traditional avenues of diagnosing heart attacks such as physical examination and blood tests. As a result, it helps technicians pick out SMIs, which, if left undetected and unaddressed, can increase the likelihood of a more serious and potentially fatal heart attack in the future. 

Tombstoning patterns in the J point might point to anterior MI 

In a normal electrocardiogram, a P wave precedes the QRS complex. In between those is the PR segment which details the electrical activity transitions to the ventricles from the atria. Then follows the QRS complex which comes before the ST segment that finally leads up to the T wave.

Now that we’ve established the normal ECG detailing in our minds, let’s now move into how to read an MI ECG. For our purposes, we’ll consider specifically, anterior ST-segment elevation MI (STEMI) on a 12-lead ECG. There are quite a number of patterns that you may encounter on an ECG for anterior MI.

One of the most common ones is tombstoning. In this case, the T wave, in combination with an elevated J point, results in a tombstone-like shape on the ECG along the QT interval (you can see this in V2 and V3). Remember that the J point comes at the end of the QRS complex as it joins the ST. Overall, many anterior MI cases are consistent with J-point elevation

Elevation of the ST and an early Q wave could be a sign of Inferior MI

There exist various variations of myocardial infarction, depending on the region of the heart they affect. We’ve already discussed one of the most acute MIs in the second point i.e. Anterior MI (which affects the heart’s arterial walls), now we’ll move on to another type: inferior wall myocardial infarction (IWMI). The latter is often the consequence of a problem with the right coronary artery. 

So how do you identify an inferior STEMI (considering the case of a 12-lead ECG)? Many STEMI MI ECG interpretation services suggest technicians should take the following into account as possible giveaways: 

• Early formation of the Q wave
• The above often comes with an ST elevation in aVF, III, and II
• Moreover, the ST elevation in lead II is less than that in lead 3

Posterior MI is evidenced by ST depressions in anterior leads

Onto another type of myocardial infarction, namely posterior MI. True to its tag, it refers to MI which affects the heart’s posterior. By the time it sets in, inferior MI may have already taken root, thus you may also notice the signs of the latter on your electrocardiogram. However, there are also incidences of isolated posterior MIs as well. 

So what does a posterior MI look like on ECG? Well, you need to pay particular attention to anterior leads and observe for ST depressions. You’ll notice that they are horizontal or flat, and deep (i.e. greater than 2 mm)

Moreover, when you zoom in on leads V2 or V1 you should be able to pick out certain characteristics. For instance, the R wave to S wave ratio will be more than one. Additionally, across posterior leads, you may also notice elevation of the ST. 

An RBBB reading may be an indication of MI

You should still be able to pick out an ST-elevation myocardial infarction from your ECG regardless of whether the patient has a right bundle branch block (RBBB) or not.

So how can you tell RBBB on ECG? An RBBB can often accompany inferior as well as anterior MIs and you should watch the aVL and lead I for reciprocal depressions which might point toward an IWMI with RBBB. Some other ECG findings that often resonate with RBBB include: 

• The R wave lasts for a smaller period than the S wave
• The S wave exceeds a duration of 40 ms
• QRS duration matches or exceeds 120 ms

It’s worth noting that the presence of RBBB may succeed an MI, although it isn’t always a surefire indicator of myocardial infarction. 

Trust Techindia for ECG interpretation support 

How hard is it to read an ECG? Well, standard ECG interpretation can be challenging. Technicians need to stay on top of their game and sharpen their pattern recognition skills regularly to successfully read ECGs. Deciphering MI ECGs can be a challenge because of the different varieties there are, and overlapping waves. Hopefully, our article today has helped shed more light on how to go about the process. Should you need to outsource interpretation to a reputable ECG interpretation services provider, Techindia is here to help you out. Our AI-driven technology and vastly experienced team of ECG technicians with over 21,000,000 ECG reporting hours can help you diagnose any arrhythmia or heart problem. Call us now to get started.