Coronary angiography:
preparation, how it is performed, and what happens afterward

Article written and reviewed by Dr Luca Moretti

Coronary angiography, or a coronary angiogram, is an invasive test that makes it possible to visualize the coronary arteries directly using a catheter introduced into an artery, usually through the wrist or groin, and the injection of iodinated contrast medium. It is used when the presence and extent of coronary artery narrowing or occlusion need to be defined precisely and, in certain situations, it may be followed during the same procedure by angioplasty.
Preparation is not simply a matter of arriving fasting: before the test it is especially important to follow the center's instructions, report all medications you take, any previous reactions to contrast medium, diabetes, kidney disease, and other relevant conditions. Anticoagulants, antiplatelet drugs, or diabetes medications should not be stopped on your own initiative.

Before the test, it is useful to make sure you have:

• the instructions you received about food and drinks in the preceding hours;
• an up-to-date list of medications and doses, including anticoagulants and diabetes medications;
• if requested, recent blood tests, particularly those relating to kidney function;
• information about allergies or previous reactions to contrast media;
• available cardiology documentation and previous test results;
• arrangements for getting home when the center advises against driving after the procedure or after sedation.

Coronary angiography is part of the invasive assessment of ischemic heart disease, but it is not necessary in every person with chest pain or suspected coronary artery disease. The decision depends on the clinical context, tests already performed, estimated risk, and the likelihood that the result will change treatment.

How to prepare for coronary angiography

In the days before the procedure, the center may request blood tests to check hemoglobin, coagulation, and especially kidney function, because iodinated contrast medium is eliminated predominantly through the kidneys. Anyone with kidney disease, a recent worsening of kidney function, or other risk factors should report this: the team may adapt the strategy, contrast volume, and preventive measures.
It is equally important to report any previous reactions to iodinated contrast media. A previous reaction does not automatically mean that the test is absolutely contraindicated, but it may require a specific assessment and, in some cases, preventive measures.

There is no universal list of medications that must be stopped. Anticoagulants such as warfarin, apixaban, rivaroxaban, dabigatran, or edoxaban may require different management depending on bleeding risk and the procedure planned. Diabetes treatment, including insulin and metformin, may also require individualized instructions, especially when fasting is planned or kidney function is reduced.
For this reason, the practical rule is simple: report everything you take in advance and follow the written or verbal instructions provided by the center. Stopping an anticoagulant or antiplatelet drug on your own may expose you to avoidable risks.

Protocols may also differ regarding fasting. Some centers allow water and, in certain circumstances, even a light breakfast; others require several hours without food, especially if sedation is planned or if the procedure may turn into an intervention. The correct instruction is therefore the one provided by the facility performing the test, not a rule found online.
Before the procedure, your medical history, informed consent, blood pressure, and clinical parameters are also checked. It is useful to report a possible pregnancy, recent bleeding, ongoing infections, or any important change in your health that has occurred since the procedure was scheduled.

How it is performed: from the wrist or groin to the coronary arteries

Coronary angiography is performed in a cardiac catheterization laboratory. The patient is generally awake; light sedation may be given if necessary. After disinfection, local anesthesia is administered at the access site, most often the radial artery at the wrist or, in selected situations, the femoral artery in the groin. Radial access is now frequently preferred because it reduces bleeding complications related to the puncture site, although it is not suitable in every situation.
A thin catheter is introduced through the artery and guided to the origin of the coronary arteries under X-ray guidance. The catheter is not inserted into the heart muscle, and its passage through the blood vessels is normally not perceived as painful.

When contrast medium is injected into the coronary arteries, X-ray images are recorded from different angles. Some people experience a brief generalized sensation of warmth, nausea, or an unusual feeling; heart rhythm, blood pressure, and oxygenation are monitored throughout the test. Any chest pain, breathing difficulty, itching, or other symptoms should be reported to the staff immediately.
A purely diagnostic coronary angiogram may be relatively brief, but its duration varies according to the anatomy, ease of access, and any additional assessments. When a stenosis has uncertain significance, the interventional cardiologist may use physiological measurements or intracoronary imaging techniques to decide whether a lesion should be treated.

What it can show and why not every stenosis requires a stent

The report may show coronary arteries without significant narrowing, nonobstructive plaques, one or more stenoses, or an occlusion. The significance of a stenosis does not depend only on the percentage seen on angiography: its location, the extent of disease, the myocardial territory involved, symptoms, and, when necessary, evidence that the lesion actually limits blood flow all matter.
For this reason, finding a stenosis does not automatically mean placing a stent. In some cases the best choice is to optimize medical therapy; in others, myocardial revascularization by angioplasty or coronary artery bypass surgery is indicated.

If the possibility of an intervention has already been discussed and authorized, coronary angiography may be followed immediately by angioplasty with stent implantation. In other cases, the team may prefer to stop after the diagnostic study and discuss the alternatives later, especially when the anatomy is complex or when PCI and surgery need to be compared.
The guide on the coronary stent separately describes how angioplasty is performed and which treatments are required after implantation.

What happens after coronary angiography and which warning signs to watch for

At the end of the procedure, the catheter is removed and the access site must be compressed or closed to achieve hemostasis. After radial access, a compression device is often applied to the wrist; after femoral access, compression, a closure device, and a longer period in bed may be necessary. During observation, blood pressure, pulse, the puncture site, and the patient's general condition are monitored.
After an uncomplicated diagnostic coronary angiogram, many people can go home the same day, but this is not a rule. Observation may be longer after femoral access, in the presence of clinical problems, kidney impairment, bleeding, significant sedation, or if angioplasty was also performed.

A small hematoma or some tenderness at the puncture site is common. The center provides instructions about showering, dressings, physical activity, lifting weights, and driving. Drinking normally, when there are no restrictions because of heart failure or other medical reasons, helps maintain good hydration; forcing large amounts of fluids without an indication is not useful.
A bleed that does not stop with compression, rapidly increasing swelling, significant pain at the access site, a cold or pale hand or leg or altered sensation, breathing difficulty, fainting, or a general deterioration require prompt assessment. New severe chest pain or pain compatible with ischemia should be treated as a possible emergency and should not automatically be attributed to the procedure.

Frequently asked questions about coronary angiography

Do you need to fast before coronary angiography?
Not always in the same way. Instructions vary according to the center, sedation, and the possibility that an intervention will be performed. You should follow the instructions you receive exactly and should not extend fasting on your own initiative.
Which medications should be stopped?
None on your own. Anticoagulants, diabetes medications, and other treatments may require individualized changes; the center must know the complete list of medications and provide precise instructions.
Is coronary angiography painful?
The access site is numbed. You may feel pressure or discomfort and a brief sensation of warmth when contrast is injected, but significant pain should always be reported to the staff.

Can you go home the same day?
It is often possible after an uncomplicated diagnostic test, especially with radial access, but the decision depends on your clinical condition and what was done during the procedure.
If a stenosis is found, is a stent always placed?
No. The choice among medical therapy, angioplasty, and bypass surgery depends on coronary anatomy, the significance of the lesions, and the overall clinical picture.