30 March, 2024

Coronary Angiography: Ideas, Concepts, and Expectations

Introduction:
Taking a direct look at the heart’s blood vessels (known as coronary arteries) is called ‘Coronary Angiography’ (CAG). Click here for more information on coronary angiography and angioplasty. Your cardiologist may suggest you undergo a CAG if he/she suspects blockages in your heart blood vessels. Such suspicion may arise from routine medical examinations or any specific abnormalities seen in investigations like ECG, echocardiogram, blood test, or stress test. Certain basics of CAG were discussed in my previous blog. Here I will expand the discussion further.

The Procedure:
CAG involves placing a short flexible tube in a blood vessel of the wrist or groin, through which another long flexible tube (called a catheter) is threaded up to the heart. Contrast (or dye) is a special liquid which, when injected into the heart blood vessel via this catheter, allows the blood vessels to be seen under x-ray. An animation of angiography can be found here. The Heart Foundation summarizes the basics of CAG which can be found here. Below is an image of one of the many routine catheters used for angiography.

Basics:
CAG typically takes about 20 minutes of preparation time and another 15 minutes to perform the procedure. CAG can be performed via wrist almost 95% of the time. In 5% of cases, CAG is done from the leg (groin area). Although there are many technical differences between doing CAG from the wrist versus the groin, from the patient’s standpoint, the basic differences are two: First, the groin route has a slightly higher chance of bleeding. Second, patients need to be on strict bed rest for a few hours (typically 4 to 6 hours) after the procedure to reduce the risk of bleeding. Many factors determine which site should be chosen for CAG and should be best left to the performing physician to decide. The procedure is performed in a special Cardiac Catheterization Laboratory (Cath Lab) suite. CAG is typically performed under local anaesthesia, with mild sedation to keep patients comfortable. The majority of the patients undergoing CAG experience no or minimal discomfort. Results are available immediately.

Results:
Angiography can have one of the following findings:

1. Normal: This is when heart blood vessels appear normal without any apparent disease or blockages. These patients have a very small risk of future heart attack and typically require minimal or no heart medications at all.
2. Mild disease: Here, blood vessels have mild blockages (typically <50%). These patients do not require any stents or bypass surgery but need medications because even low-grade blockages have a certain risk of progressing in the future or causing a heart attack. A large study done in the year 2008 found that the median degree of blockage that led to future heart attacks was 30%.  A healthy lifestyle and certain evidence-based medicines are standards of care.
3. Significant blockage: When one or more arteries have significant blockage (typically >70%) medicines alone may not able to provide the required benefit. Here, along with lifestyle modifications and medications, stents may be required. It must be noted that the decision to place a stent or not is based on multiple other parameters. There are scenarios when stenting a more than 70% blockage is not recommended. Also, there are contra scenarios when even a 50% blockage may be recommended for stenting.
4. Severe disease: When patients have multiple complex blockages, they are best served with open-heart bypass surgery called CABG (Coronary Artery Bypass Grafting). Here, decision-making is also not at all algorithmic. Location and complexity of the blockages, age, other medical issues, etc. are among a few of the parameters considered before deciding whether CABG is a good option or not.

Acuity (Urgency of decision making):
If CAG is done for an active heart attack and reveals major blockage, such a situation should be handled in a time-sensitive manner. There is continuous cell death during a heart attack and any delay in opening up a blocked blood vessel increases the incurred damage to the heart muscle. Such damage is mostly permanent. Time is of the essence here, and all attempts should be made to quickly halt any further heart damage by opening up the blocked blood vessel as soon as possible. Furthermore, delay in such cases increases the risk of heart attack-related death.
When CAG is done for indications other than a heart attack, like for chest pain evaluation, or a positive stress test etc., here we have time to make a thoughtful decision. In many such scenarios, if significant blockage is identified in one or two blood vessels which are amenable to stents with low risk, it is reasonable to go ahead with stents in the same setting (ad-hoc) rather than bringing the patient back in for a second procedure (staged). Procedural risks add up with every repeat procedure and should be avoided if possible. More than 90% of all stenting in developed countries is done on an ad-hoc basis whereas most of the non-urgent stent procedures in India are staged. When there is any doubt in decision-making, and there is no active heart attack, it is reasonable to pause and seek a second opinion with another cardiologist before proceeding with stents or CABG.

Complications:
Since CAG involves catheter movement inside the body, placing the catheter in and around the heart, and injecting contrast, there is always a chance of things not going as planned. With technological advancements and procedural skills, such complications have become quite uncommon. CAG, if done by experts, carries less than a 1% risk of any major complication, with more than 99 out of 100 patients completing the procedure without any major issues. There is no downtime after the procedure, meaning the patient can resume most of the daily physical activities the following day. This is particularly true if the procedure is performed via the wrist. There are certain situations where the procedure risks can be higher than average. Such scenarios demand extra precautions. Inform your doctor if you have any of the following as he/she may be able to make certain adjustments to the procedure to minimize the risk. Also, please disclose all the medications you are taking to avoid any undesirable interactions.

Conditions that increase the risk of an angiogram are:
Active or past kidney disease
Active or past lung disease
Active infection (or if you are taking antibiotics)
Being on blood thinners
Allergy to contrast/dye or any other medication
Any stents placed in the groin/thigh/leg region
Allergy to latex
Pregnant women etc.
*If you have any of these, certain adjustments can be made to minimize the procedural risk

Things to know:

1. If you plan to seek a second opinion after CAG, obtain a CD containing angiography videos. Looking at a report alone is not sufficient for any cardiologist to give a sound opinion. WhatsApp images have poor resolution and can’t be relied upon for professional opinion.
2. Although there are alternatives to CAG, they all have limitations, and CAG remains the gold standard.
3. It is ok to ask the operating physician about his/her training and experience in doing CAG.

Things to look out for after CAG:
Please keep an eye on the procedural site (wrist or groin). The area should be kept clean and dry for about 24 hours. It is ok to take a shower after 24 hours. Report to the nearest hospital immediately if you notice rapidly developing swelling, redness, pain, and sensation changes. Also, any worsening heart-related symptoms like chest pain or breathing discomfort, dizziness, excessive nausea, vomiting, etc. deserve a hospital visit. While the likelihood of such things is very low, one should be aware of the possibilities.

If the procedure is done through the leg, heavy weight lifting (anything more than 5 kg) should be avoided for 48 hours. Similarly, any brisk leg motion, such as kickstarting a motorbike, running up and down the stairs, or kicking a football, should be avoided for a few days. These precautions ensure no late bleeding occurs at the procedural site.

Drink a generous amount of fluids after the procedure for the first 24 hours to flush off contrast/dye given during the procedure, unless the treating physician instructs otherwise.

I am sure I didn’t answer all your questions on this topic. Feel free to message me with your queries; I will happily answer them.

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