Hello. Thank you for your question and welcome to HCM. I understand your concern. Let us treat the problems one by one. Now, in medicine, every decision is carried out by a doctor who carefully weighs the benefit/risk balance. If a coronary artery narrowing or blockage is left untreated with a stent placement, then that artery will surely totally close and give you a heart attack. This is the primary problem in these cases. In your particular case, you said that you have problems with your stomach. Indeed, aspirin and non-steroidal anti-inflammatory drugs (NSAIDs) irritate the stomach inner lining by blocking an important factor which inhibits the acid production in the stomach (prostaglandins). From now to the end, I will share my and our clinic s experience in these cases. First, I would order an upper gastrointestinal (GI) endoscopy, to see if there is an actual problem in your stomach, such as gastro-oesophageal reflux disease (GERD), chronic gastritis or ulcer. If there is a present inflammation there, I would withhold the procedure, until this inflammation is healed. If there is not, then you can take aspirin and clopidogrel, accompanied, of course, with a stomach mucosa protector (anti-H2 hystamine receptor drugs or protein pump inhibitor (PPI) drugs). As for the novocain, yes, it contains sulfite derivatives, which can cause allergic reactions, ranging from mild to true, life-threatening, anaphylactic shock. Lidocaine is used in our clinic, which also contains sodium metabisulfite. However, the need for stent placement is critical. So, you would be safe if an anti-allergic reaction protocol is used, which consists on: - prednisolone 2 x 25 mg (amp), given 13, 7 and 1 hour before the procedure, and - telfast 1 x 180 mg (tb), given 13 and 1 hour before the procedure. I hope I was clear, helpful and thorough with my answer. Good luck with the procedure. Best regards.