Preparing for Your CTCA at Epoch Medical Imaging, St Ives
Preparing for your CTCA at Epoch Medical Imaging, St Ives. Fasting, medications, heart rate and contrast requirements. North Shore cardiac CT specialist.
How to Prepare for a CT Cardiac Angiogram — Medications & Heart Rate
A CTCA requires specific preparation to ensure the scan produces the highest possible image quality — and therefore the most clinically useful results for your cardiologist or GP.
Key preparation steps:
Fasting:
– Fast for 4 hours before your appointment. Water and prescribed medications are always permitted.
Caffeine:
– Avoid all caffeine for 12 hours before your scan — including coffee, tea, cola drinks, and energy drinks. Caffeine elevates heart rate, which significantly affects image quality.
Medications:
– Continue all regular medications as normal on the day of your appointment, including blood pressure medications — unless specifically advised otherwise by your GP.
– Beta blockers: If your resting heart rate is likely to be above 65 beats per minute, your cardiologist or GP may prescribe a beta blocker tablet to take 1 to 2 hours before your scan to optimise your heart rate. Please bring this medication to your appointment.
– Metformin: If you take metformin for diabetes, you may be asked to pause it for 48 hours after the scan — your GP will advise.
– GTN spray: If you use GTN spray for angina, bring it to your appointment.
Our team at Epoch Medical Imaging in St Ives will provide full preparation instructions specific to your CTCA when you book on (02) 9129 6999.
What Happens During the CTCA Procedure at Epoch
Knowing exactly what to expect on the day of your CTCA at Epoch Medical Imaging helps reduce any anxiety and ensures you arrive well prepared.
Step by step on the day:
1. Arrival and registration: Arrive at the time confirmed by our team. Our staff will register you and confirm your preparation and medical history.
2. Heart rate assessment: Your resting heart rate is measured with an ECG. The target heart rate for optimal image quality is typically below 60 beats per minute. If needed, a beta blocker tablet or IV medication is given at this stage.
3. ECG electrodes: Sticky ECG electrodes are placed on your chest to monitor your heart rhythm continuously during the scan.
4. IV cannula placement: A small IV cannula is inserted into a vein in your arm — used for the contrast injection during the scan.
5. Positioning and scan: You lie on the scanning table, which moves through the CT ring. You will be asked to hold your breath for approximately 10 seconds during the scan. The contrast is injected automatically during the scan.
6. Post-scan: The cannula is removed. You are observed briefly and then free to go. The entire appointment typically takes 45 to 60 minutes.
Beta Blockers & Heart Rate Control Before a CTCA
Heart rate control is one of the most important technical factors determining CTCA image quality — and it is worth understanding why.
Why heart rate matters for CTCA:
– The coronary arteries are tiny vessels — 1 to 4 mm in diameter — that move continuously with each heartbeat.
– At higher heart rates (above 65–70 bpm), the arteries move more rapidly during the scanning window, causing motion blurring that can obscure fine detail.
– At lower heart rates, the arteries are more stationary during the brief scanning period, producing sharper, clearer images.
How heart rate is managed:
– Many patients achieve an adequate heart rate naturally after resting quietly and avoiding caffeine — particularly those on regular beta blocker medication.
– If the resting heart rate is above 65 bpm, a beta blocker tablet (typically metoprolol) may be prescribed by your GP to take 1 to 2 hours before the scan.
– For some patients, an IV beta blocker may be given on the day if the oral medication has not lowered the heart rate sufficiently.
– Beta blockers are generally very safe and well-tolerated. If you have known asthma, severe chronic obstructive pulmonary disease (COPD), or a known allergy to beta blockers, inform our team when booking.
Contrast Dye Allergy & Kidney Function Checks Before CTCA
Before administering the contrast dye needed for a CTCA, two important safety checks are routinely performed.
Kidney function assessment:
– Iodine-based contrast dye is cleared from the body by the kidneys. In patients with significant kidney impairment, contrast can temporarily worsen kidney function — a condition called contrast-induced nephropathy.
– A recent blood test measuring kidney function (eGFR/creatinine) is required before your CTCA. Your GP will arrange this.
– Patients with mildly reduced kidney function can usually still have a CTCA with appropriate hydration and precautions. Those with significantly reduced function will be assessed individually by our radiologist.
– Metformin should be paused for 48 hours after contrast in patients with certain levels of kidney function — your GP will advise.
Contrast allergy assessment:
– A known allergy to iodine-based contrast is important to declare when booking your CTCA.
– Most patients with a previous mild contrast reaction can still undergo CTCA with pre-medication — typically a course of oral corticosteroids taken before the scan.
– Patients with a previous severe contrast reaction require specialist assessment before proceeding.
All safety checks are reviewed by our radiologist before your scan at Epoch Medical Imaging in St Ives.
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