What should I know about coronary artery disease if I am planning non-heart surgery? 

When you have Coronary Artery Disease (CAD), undergoing non-cardiac surgery (like a hip replacement, gallbladder removal, or cataract surgery) requires careful planning. While the surgery itself might be on your leg or stomach, the anaesthetic affects your entire cardiovascular system. To an anaesthetist, surgery is a ‘stress test,’ it creates a demand for oxygen that a compromised heart might struggle to meet. However, with the right preparation, the risk is highly manageable. 

What We’ll Discuss in This Article 

• The ‘Physiological Marathon’: Why surgery puts the same strain on your heart as a race. 

• The Stent Timeline: Why you might need to delay elective surgery for 12 months. 

• Blood Thinners: The delicate balance between preventing clots and preventing bleeding. 

• The ‘METs’ Score: The simple stair test anaesthetists use to grade your risk. 

• Medication Rules: Why you should take your beta-blocker but skip your ACE inhibitor. 

• Post-Op Danger: Why the first 3 days after surgery are the riskiest. 

The Anaesthetic Strain 

Many patients believe anaesthesia is just ‘going to sleep., It is much more complex. 

General anaesthesia causes profound changes in your physiology: 

• Blood Pressure Drops: Anesthetic drugs dilate blood vessels. 

• Heart Rate Spikes: The stress of the surgery (pain response) releases adrenaline. 

• Clotting Risk: The inflammation from the wound makes your blood ‘sticky.’ 

• The Consequence: If your coronary arteries are narrowed, the drop in blood pressure combined with a racing heart can starve the heart muscle of oxygen (ischemia) during the operation. 

The Stent Timeline (The 12-Month Rule) 

If you have a stent, timing is everything. 

Elective surgery poses a massive risk for patients with recent stents because surgery increases inflammation (clot risk) but requires you to stop blood thinners (bleeding risk). 

• Bare Metal Stents: You typically need to wait at least 4 weeks before elective surgery. 

• Drug-Eluting Stents (Modern): Ideally, you should wait 12 months after insertion. In some cases, this can be reduced to 6 months, but operating sooner carries a high risk of ‘Stent Thrombosis,’ a sudden clot in the stent which causes a massive heart attack. 

The Blood Thinner Dilemma 

This is the most difficult decision for the surgical team. 

• Antiplatelets (Aspirin/Clopidogrel): Surgeons hate them because they cause bleeding. Cardiologists love them because they keep the stent open. 

• The Compromise: 

• Aspirin: Usually continued throughout surgery (except for very high-risk procedures like brain or eye surgery). 

• Clopidogrel/Ticagrelor: Usually stopped 5–7 days before surgery. 

• Warfarin/DOACs: Stopped 2–3 days before. 

• The Golden Rule: Never stop these drugs yourself. Wait for the specific instruction from the Pre-Operative Assessment clinic. 

The Functional Test (METs) 

Your anaesthetist will ask: ‘Can you climb two flights of stairs?’ 

They are calculating your Metabolic Equivalent of Task (METs). 

• > 4 METs: If you can climb two flights of stairs or walk up a hill without stopping, your heart has good functional reserve. Your surgical risk is low. 

• < 4 METs: If you get breathless walking on flat ground, your heart may struggle with the stress of surgery. You might need a ‘Stress Echo, scan before you are cleared for the operation. 

Medication Morning: Stop or Go? 

On the morning of surgery, you will be fasting (nil by mouth). However, some pills must still be taken with a sip of water. 

• TAKE: Beta-blockers (Bisoprolol/Atenolol). Stopping these suddenly causes a dangerous rebound in heart rate. 

• STOP: ACE Inhibitors (Ramipril) and Diuretics (Furosemide). These can cause your blood pressure to crash too low under anaesthesia. Usually, you skip the morning dose and restart the next day. 

• STOP: Diabetes medications (Metformin/Insulin) are usually held or adjusted because you are not eating. 

The ‘Silent’ Recovery 

The highest risk period is not on the operating table; it is the first 72 hours after surgery. 

• Silent MI: Because you are on strong painkillers (morphine), you might not feel the chest pain of a heart attack. You might just feel breathless, nauseous, or unusually tired. 

• Monitoring: If you are high risk, the doctors may check your Troponin levels (heart enzymes) and do an ECG daily for three days after surgery to catch any silent issues. 

Conclusion 

Having CAD does not mean you cannot have surgery. It simply means the ‘Pre-Operative Assessment’ is the most important appointment of the process. Be honest about your exercise tolerance (stairs), bring your exact medication list, and if you have a stent less than a year old, ask your surgeon if the operation can wait. 

Would you like me to create a ‘Pre-Op Medication Checklist’ template where you can list your drugs and tick ‘Stop’ or ‘Continue’ based on your doctor’s instructions? 

Authority Snapshot 

This article was written by Dr. Rebecca Fernandez, a UK-trained physician (MBBS) with extensive experience in perioperative medicine. Dr. Fernandez has worked closely with anaesthetists and surgeons to assess ‘high-risk’ patients before operations. She explains the critical safety checks required to ensure your heart can withstand the stress of surgery, aligning with the latest guidelines from the European Society of Cardiology (ESC) and NICE.