If you already take metoprolol for high blood pressure, heart failure, or another chronic condition, the standard medical advice is to keep taking it before surgery. Both American and European cardiology guidelines recommend continuing beta-blocker therapy in patients who are already on it, rather than stopping before a procedure. But the picture changes sharply if you have never taken metoprolol and someone proposes starting it shortly before an operation. A landmark trial involving over 8,000 patients found that fresh use of extended-release metoprolol before non-cardiac surgery reduced heart attacks but increased deaths and strokes, a tradeoff that reshaped how surgeons and anesthesiologists think about perioperative beta-blockers.
Why Stopping Metoprolol Before Surgery Is Risky
If you have been on metoprolol for weeks, months, or years, your body has adapted to its effects. Your heart rate is being held at a lower level, your blood vessels respond differently to stress hormones, and your cardiovascular system has essentially recalibrated around the drug. Abruptly withdrawing a beta-blocker can trigger a rebound effect: your heart rate spikes, blood pressure surges, and your risk of a dangerous cardiac event goes up at precisely the worst moment, during the stress of surgery.
This withdrawal phenomenon has been recognized since the 1970s, and more recent research has reinforced how harmful it can be around the time of an operation.1PubMed Central. Beta-blocker withdrawal among patients presenting for surgery from home A large observational study found that patients whose beta-blockers were not continued on the day of surgery and during the postoperative period had roughly double the odds of a serious adverse event within 90 days. For patients with higher cardiac risk, the odds were even worse.2PubMed Central. β-Blocker Continuation After Noncardiac Surgery: A Report From the Surgical Care and Outcomes Assessment Program
The takeaway is straightforward: if your doctor has had you on metoprolol and you have surgery coming up, do not skip doses on your own. The morning-of-surgery instructions from your surgical team will almost always tell you to take your beta-blocker with a small sip of water, even when you are otherwise fasting. This is one of those medications that falls into the “keep taking it” category for nearly every type of procedure.
The Problem With Starting Metoprolol Right Before Surgery
The question gets more complicated when a patient is not currently on a beta-blocker and someone considers starting one to protect the heart during surgery. The idea is intuitive: surgery stresses the cardiovascular system, beta-blockers dampen that stress, so maybe giving one beforehand prevents heart attacks. For years, that logic drove widespread preoperative beta-blocker prescribing. Then a major randomized trial punctured the assumption.
The POISE trial gave extended-release metoprolol succinate or a placebo to over 8,300 patients undergoing non-cardiac surgery, starting the drug two to four hours before the operation. The results were mixed in the most uncomfortable way possible. Patients in the metoprolol group did have fewer heart attacks: about 4% compared to nearly 6% in the placebo group. But they also had more deaths, roughly 3.1% versus 2.3%, and more than double the rate of stroke.3PubMed. Effects of extended-release metoprolol succinate in patients undergoing non-cardiac surgery (POISE trial): a randomised controlled trial The trial’s own authors concluded that patients are unlikely to accept the risks that came with starting this regimen right before an operation.
The core issue was that the drug caused significant drops in blood pressure and heart rate, and those episodes of low blood pressure appear to have driven the excess strokes and deaths. A heart that beats slower is less likely to suffer an ischemic event, but a brain that gets insufficient blood flow because pressure dropped too low is more likely to suffer a stroke. The POISE results did not mean beta-blockers are bad around surgery; they meant that starting a high dose in a beta-blocker-naive patient just hours before an operation is a dangerous gamble.
Timing Changes Everything
One of the clearest lessons from the research is that when you start a beta-blocker relative to surgery matters enormously. A study of vascular surgery patients found that starting a beta-blocker more than a week before the operation roughly halved the odds of a cardiac event within 30 days and cut long-term mortality compared to starting within the final week.4PubMed. Timing of pre-operative Beta-blocker treatment in vascular surgery patients: influence on post-operative outcome The body needs time to adjust to the drug, and the dose needs time to be titrated up gradually so the patient does not walk into the operating room on a medication their system has barely met.
This is essentially why the POISE trial produced its troubling results. Patients received a large dose of a long-acting beta-blocker on the same day as surgery, with no opportunity to see how their body would handle it. If someone had become hypotensive the day before surgery, the dose could have been lowered. But starting that day left no room for adjustment. Current guidelines from the ACC/AHA now recommend that if there is a reason to start a beta-blocker before surgery, it should be done at least a day beforehand, and ideally more than a week in advance, with gradual dose titration.5PubMed Central. PURLs: Why you shouldn’t start beta-blockers before surgery
How Your Surgical Team Decides Whether You Need It
Not every patient heading into surgery needs to be on a beta-blocker. Whether it makes sense depends on your baseline cardiac risk and the type of operation. A review in JAMA outlined how clinicians typically assess this: risk calculators identify patients with low risk (under 1% chance of a major cardiac event during or shortly after surgery) and higher risk (1% or above). For low-risk patients, cardiac testing and additional medications are rarely warranted. For higher-risk patients, further assessment might include checking whether you can handle moderate physical exertion, like climbing two flights of stairs, without symptoms.6JAMA. Perioperative Cardiovascular Risk Assessment and Management for Noncardiac Surgery: A Review
If you are already on metoprolol for hypertension, atrial fibrillation, or heart failure, the risk calculation is simpler. You continue your medication because stopping it creates a bigger problem than continuing it. The harder decisions involve patients who have significant cardiac risk factors but have never been on a beta-blocker. For these patients, the cardiologist and surgical team weigh whether the protective benefit against heart attacks outweighs the risks of hypotension and stroke, especially given how the POISE results played out. In practice, the trend since POISE has been to be much more cautious about new perioperative beta-blocker prescriptions.
What Happens in the Operating Room
Metoprolol’s effects do not pause once anesthesia begins. If you took your dose that morning, your anesthesiologist will be managing its ongoing influence on your heart rate and blood pressure throughout the procedure. Research has shown that preoperative metoprolol provides somewhat better cardiovascular stability during surgery: the heart rate stays slightly lower and blood pressure fluctuations are more moderate.7PubMed. Preoperative metoprolol improves cardiovascular stability and reduces oxygen consumption after thoracotomy
The flip side is that combining a beta-blocker with anesthetic agents, which also lower blood pressure and heart rate, can occasionally produce an exaggerated effect. In rare cases, severe bradycardia has been observed, where the heart rate drops to dangerously low levels.8PubMed. Haemodynamic effects of pretreatment with metoprolol in hypertensive patients undergoing surgery Anesthesiologists are trained to handle this. If blood pressure drops too much, they can give fluids or medications to support it. If the heart rate slows excessively, anticholinergic drugs can bring it back up. In some surgeries where very tight heart rate control is needed intraoperatively, teams may use esmolol, an ultra-short-acting beta-blocker given by IV that wears off within minutes of stopping it, rather than relying solely on a long-acting oral dose taken hours earlier.
Metoprolol Tartrate Versus Metoprolol Succinate
Metoprolol comes in two formulations, and the distinction matters more than you might expect around surgery. Metoprolol tartrate is the immediate-release version, typically taken twice daily. Metoprolol succinate is the extended-release version, taken once daily. The POISE trial used the extended-release form, which means a large, sustained dose that the body could not quickly clear if problems arose.
A study comparing the two formulations on the day of surgery found that heart rates were similar between patients on tartrate and those on succinate, but both groups ran higher than patients on atenolol, a different beta-blocker that tends to produce more consistent heart rate control on the morning of an operation.9PubMed Central. Atenolol Is Associated with Lower Day of Surgery Heart Rate as compared to Long and Short-acting Metoprolol This has led some clinicians to prefer atenolol or bisoprolol for perioperative use, though metoprolol remains the most commonly prescribed in practice.
There is another practical wrinkle with the extended-release form. If your surgery involves the gastrointestinal tract, the controlled-release mechanism can be disrupted. A study of patients who had gastric bypass surgery found that the bioavailability of metoprolol from controlled-release tablets dropped significantly after the procedure, meaning the body absorbed much less of the drug than before surgery.10European Journal of Hospital Pharmacy. Effect of Roux-en-Y gastric bypass on the bioavailability of metoprolol from immediate and controlled release tablets: a single oral dose study before and after surgery The immediate-release form was less affected. If you have had bariatric surgery or are undergoing a procedure that changes your stomach or intestine, your doctor may need to adjust which form you take or switch to a different delivery method.
Why Metoprolol Specifically Raises Stroke Concerns
Not all beta-blockers carry the same risk profile around surgery, and metoprolol has drawn particular scrutiny for strokes. A large single-center study of over 44,000 surgical patients found that perioperative metoprolol was associated with more postoperative strokes compared to bisoprolol, a more selective beta-blocker.11Anesthesiology. Selective β1-Antagonism with Bisoprolol Is Associated with Fewer Postoperative Strokes than Atenolol or Metoprolol: A Single-center Cohort Study of 44,092 Consecutive Patients The proposed mechanism involves how different beta-blockers interact with receptors that control blood vessel dilation in the brain. More selective drugs may preserve cerebral blood flow better during the stress of surgery.
This does not mean metoprolol is unsafe for every surgical patient. Millions of people continue their metoprolol through operations without incident. But the finding does influence which beta-blocker a physician might choose if they are starting one fresh for perioperative protection, and it adds another layer to why the blanket recommendation to “just give metoprolol before surgery” has fallen out of favor.
Your Genetics May Affect How Well Metoprolol Works
Metoprolol is broken down in the liver by an enzyme called CYP2D6, and people vary widely in how active this enzyme is. Some people metabolize the drug very quickly, so it wears off faster and may not provide adequate coverage through surgery. Others metabolize it slowly, leading to higher drug levels that increase the risk of side effects like low blood pressure and slow heart rate.
A study of over 5,200 patients undergoing coronary artery bypass grafting looked at whether this metabolic difference mattered for surgical outcomes. Patients on beta-blockers that depend on CYP2D6 for metabolism, including metoprolol, had a mortality rate of about 2.1%, compared to just 0.8% for patients on beta-blockers that bypass that enzyme. After statistical adjustment, the non-CYP2D6-dependent beta-blockers were associated with significantly lower operative mortality.12Journal of Thoracic and Cardiovascular Surgery. Influence of Cytochrome P-450 2D6-Dependent Metabolism on Operative Mortality After Coronary Artery Bypass Grafting Surgery This is a single study and should not be over-interpreted, but it suggests that individual metabolic variation adds unpredictability to how well metoprolol performs during the perioperative window.
Pharmacogenetic testing for CYP2D6 status exists and is increasingly common, though it is not routine before surgery. If you know your CYP2D6 status from prior testing, it is worth mentioning to your surgical team, as it may influence whether metoprolol is the best beta-blocker choice for you.
What to Do After Surgery
Continuing metoprolol after surgery is just as important as taking it beforehand. The same study that flagged the dangers of perioperative withdrawal found that only about two-thirds of patients on chronic beta-blockers actually had their medication continued both on the day of surgery and during the postoperative period, though this improved over time from roughly 57% to 71%.2PubMed Central. β-Blocker Continuation After Noncardiac Surgery: A Report From the Surgical Care and Outcomes Assessment Program The gap often happens because of the chaos of the perioperative period: different teams are managing different aspects of your care, and a home medication can slip through the cracks.
If you cannot swallow pills after surgery because of nausea, a procedure involving your throat, or being on a ventilator, the surgical team may give IV alternatives to maintain some beta-blocker coverage until you can resume oral dosing. The important thing from your perspective is to make sure your medication list, including metoprolol with the exact dose and formulation, is clearly communicated to every member of your care team.
Common Gaps in Preoperative Medication Advice
Even when surgical teams give the right advice about medications, patients do not always follow through as intended. A study assessing patient understanding of preoperative medication instructions found that among patients who did not follow the advice correctly, the most common reasons were forgetting the instructions, misunderstanding them, or intentionally deviating from them.13PubMed Central. Assessing Patient Understanding and Adherence to Preoperative Medication Advice Provided in Pre-Admission Clinic With a medication like metoprolol, where skipping a dose can genuinely change your risk profile during surgery, that gap between instruction and execution matters.
If you have a pre-admission clinic visit, write down which medications to take and which to hold on the morning of surgery. Bring the actual bottles with you on the day of the procedure. If your instructions say to take your beta-blocker, take it with the small sip of water you are allowed, even if you are otherwise fasting. And if you are unsure, call the surgical team’s office rather than guessing. With metoprolol, the cost of getting it wrong runs in both directions: taking it when you should not have introduced a new drug creates risk, and skipping it when your body depends on it creates a different risk. Clarity before you arrive at the hospital is the simplest way to avoid either mistake.