What Does a Cardiologist Do to Clear You for Surgery?

A cardiologist asked to “clear” you for surgery is not simply stamping an approval form. The process involves a structured evaluation of your heart health, an estimate of how likely you are to have a cardiac complication during or after the operation, and, when needed, additional testing or medication adjustments to lower that risk. The 2024 guidelines from the American Heart Association and American College of Cardiology lay out the framework most cardiologists follow, and the evaluation can range from a quick office visit to weeks of testing depending on how much cardiac risk you carry and what kind of surgery you’re having.¹

The History and Physical Come First

Before any testing, the cardiologist sits down and asks questions. A lot of questions. They want to know about existing heart conditions like coronary artery disease, heart failure, or valve problems. They’ll ask about prior heart attacks, stents, bypass surgery, or ablations. They’re also interested in risk factors that haven’t yet become full-blown disease: high blood pressure, diabetes, high cholesterol, kidney problems, smoking history, and family history of heart disease. Your current medication list matters enormously, especially blood thinners, beta-blockers, and diabetes drugs, because some of those need to be adjusted around surgery.

Your surgical team typically sends over a referral that describes the planned procedure, its urgency, and the type of anesthesia involved. This matters because a minor outpatient procedure under local anesthesia carries far less cardiac risk than, say, open abdominal surgery under general anesthesia lasting several hours. The cardiologist weighs the surgery’s inherent risk against your personal cardiac risk profile to decide what comes next.

Gauging Your Functional Capacity

One of the most important things the cardiologist assesses is how much physical activity you can handle in daily life. This is measured in metabolic equivalents, or METs. Sitting on the couch is about 1 MET. Climbing two flights of stairs is roughly 4 METs. Vigorous swimming or running pushes past 10 METs. The threshold that matters most is 4 METs: if you can climb two flights of stairs or walk briskly up a hill without chest pain, severe shortness of breath, or dizziness, your functional capacity is generally considered adequate for most surgeries.²

When your functional capacity is high, the outlook is favorable even if you have stable heart disease or several risk factors. In that scenario, the cardiologist rarely needs to order further cardiac testing, and surgery can proceed on schedule. But when you can’t reach that 4-MET mark, or when your activity level is genuinely unknown because you’ve been sedentary or bed-bound, the evaluation gets more involved. The cardiologist will then look more closely at how many additional risk factors you have and how risky the planned surgery is to decide whether you need further workup.³

Risk Calculators and How They’re Used

Cardiologists don’t rely on gut instinct to quantify your risk. They plug your clinical details into validated scoring tools. The Revised Cardiac Risk Index, or RCRI, is one of the most widely used. It considers factors like a history of heart disease, heart failure, stroke, insulin-dependent diabetes, kidney impairment, and whether the surgery is high-risk. A score of zero means low risk; higher scores push you into intermediate or high-risk territory, which triggers more evaluation.

That said, these calculators have real limitations. The RCRI was developed decades ago, and studies validating it in specific surgical populations have shown it tends to underestimate the number of cardiac complications, especially for vascular surgery. One study comparing multiple calculators in vascular surgery patients found that the RCRI significantly underpredicted adverse cardiac events for procedures like open aortic aneurysm repair.⁴ An independent validation study of the RCRI and the NSQIP calculator similarly found that both systematically underestimated predicted risks in noncardiac vascular surgery patients.⁵

What this means for you: the number a risk calculator produces is a starting point, not a verdict. Your cardiologist interprets it alongside everything else they know about you, including how well-controlled your conditions are, how recently you’ve had any cardiac events, and how urgently the surgery needs to happen.

When You Need an ECG, Echocardiogram, or Stress Test

Not everyone who gets a cardiac consult before surgery needs a battery of tests. In fact, over-testing low-risk patients can slow things down without improving outcomes. Here’s how the main tests fit into the picture.

The Electrocardiogram

A resting ECG is quick, cheap, and often the first thing ordered. It can reveal rhythm problems, prior heart damage, or conduction abnormalities. But it changes the surgical plan surprisingly rarely. One study that performed ECGs on all preoperative patients found abnormalities in about 42% of cases, yet those findings led to a change in how the patient was managed only about 0.5% of the time.⁶ The consensus now is that a resting ECG is most useful in patients over 40 who have cardiac symptoms or known heart or lung disease, rather than as a blanket requirement for everyone heading into the operating room.

The Echocardiogram

An echocardiogram uses ultrasound to look at your heart’s structure and pumping function in real time. It’s noninvasive, painless, and gives the cardiologist a wealth of information: how strongly your heart squeezes, whether your valves open and close properly, and whether there’s abnormal pressure inside the heart chambers.⁷ A cardiologist will typically order one if they hear a new or concerning heart murmur, if you have unexplained shortness of breath, if you have known valve disease, or if heart failure is suspected. Research has shown that patients heading into intermediate- or high-risk surgery who had worse echocardiographic findings, including weaker pumping function and significant valve leakage, were more likely to have major adverse events afterward.⁸

Stress Testing

Stress tests, whether on a treadmill or using a medication to simulate exercise while imaging the heart, are the step that often worries patients the most. The goal is to see whether your heart gets enough blood flow under exertion, revealing blockages that might cause trouble during the physiological stress of surgery and recovery. But a stress test is not automatically ordered for everyone. A large population-based study found that stress testing before elective surgery actually benefited patients at intermediate or high cardiac risk, improving one-year survival in those groups. For low-risk patients, though, testing was associated with harm, likely because false-positive results led to unnecessary delays or invasive follow-up procedures.⁹

Despite decades of research, the evidence that preoperative stress testing definitively improves outcomes remains surprisingly thin. A meta-analysis concluded that the available data are insufficient to make a definitive statement about whether stress testing leads to a clear-cut improvement in perioperative risk assessment overall.¹⁰ This is why the current approach is targeted: your cardiologist orders a stress test when they suspect it will change what happens next, not as a routine checkbox.

Blood Tests That Help Predict Cardiac Risk

Beyond imaging and stress tests, a blood marker called NT-proBNP has become increasingly useful. This molecule rises when the heart is under strain, and measuring it before surgery gives the cardiologist a window into how hard your heart is working even at baseline. In patients undergoing intermediate- or high-risk noncardiac surgery, an NT-proBNP level above about 450 pg/mL was an independent predictor of complications afterward, with roughly triple the hazard for a combined endpoint that included heart failure, kidney injury, and cardiac rehospitalization.¹¹

In cardiac surgery patients specifically, high preoperative NT-proBNP levels were linked to higher short-term and long-term mortality. Patients whose NT-proBNP dropped before surgery fared considerably better, with lower odds of needing intensive-care interventions and significantly better five-year survival.¹² This kind of dynamic tracking is becoming more common: rather than a single snapshot, cardiologists look at whether the number is trending in the right direction.

Medication Adjustments Before Surgery

A big part of the preoperative clearance process involves deciding which of your cardiac medications to continue, which to stop, and which might need to be started. This is where your cardiologist’s recommendations have the most immediate practical impact on your surgical experience.

If you’re already on a beta-blocker, the cardiologist will almost certainly tell you to keep taking it. Abruptly stopping beta-blockers before surgery can cause a dangerous rebound increase in heart rate and blood pressure. Statins, too, should be continued through the perioperative period and may even be started before surgery in high-risk patients, particularly those facing vascular procedures. Starting a new beta-blocker right before surgery is more controversial: while it can reduce heart muscle injury, evidence suggests it may also increase the risk of stroke and overall mortality, possibly from blood pressure dropping too low under anesthesia.¹³

Blood thinners are the trickiest medications to manage. If you have a coronary stent, guidelines recommend postponing elective surgery for at least three months after stent placement to let it heal. Throughout the perioperative period, at minimum one antiplatelet drug should be continued, and ideally both if the surgical team agrees it’s safe from a bleeding standpoint.¹⁴ If you’re on warfarin for atrial fibrillation or a mechanical heart valve, the cardiologist and surgeon will work together on a plan that might involve temporarily stopping warfarin and bridging with a shorter-acting injectable blood thinner, depending on your specific clotting risk.

Special Situations That Complicate Clearance

Severe Aortic Stenosis

If you have a severely narrowed aortic valve, noncardiac surgery carries elevated risk. The heart has to work much harder to push blood through a tight valve, and the hemodynamic swings that happen during anesthesia and surgery can be dangerous. The standard recommendation is to fix the valve first when possible. But for patients who aren’t candidates for valve replacement, carefully planned noncardiac surgery can still proceed with acceptable risk when the anesthesia team is aware of the valve problem and manages blood pressure aggressively throughout the case.¹⁵ A more recent study spanning a decade found that the degree of cardiac damage caused by aortic stenosis, not just the valve narrowing itself, was a significant risk factor for major cardiovascular events around the time of surgery.¹⁶

Implanted Pacemakers and Defibrillators

If you have a pacemaker or an implantable cardioverter-defibrillator (ICD), the cardiologist needs to ensure the device is managed properly during surgery. The main concern is electromagnetic interference from surgical instruments, especially electrocautery, which can confuse the device. Pacemakers are typically reprogrammed to a mode that prevents them from misinterpreting electrical noise as a heartbeat. ICDs need to have their shock function temporarily suspended so they don’t fire inappropriately in response to surgical equipment. External defibrillator pads are placed on the patient as a backup during the procedure.¹⁷ After surgery, the device is checked and reprogrammed back to its usual settings before you leave the hospital.

What “Cleared for Surgery” Actually Means

Patients often assume that cardiac clearance is a binary yes-or-no decision, like passing an inspection. In reality, the cardiologist’s note to the surgeon is more nuanced. It typically communicates one of several things: this patient’s cardiac risk is low enough that surgery can proceed without additional interventions; this patient’s risk is elevated but manageable with certain precautions (invasive blood pressure monitoring, an ICU bed reserved afterward, specific medication protocols); or the cardiac risk is high enough that the surgery should be delayed until a cardiac condition is optimized or treated first.

Sometimes the cardiologist recommends against surgery entirely, though this is uncommon for truly necessary procedures. More often, the conversation is about timing and preparation. A patient with newly discovered severe heart failure might need weeks of medication optimization before a hip replacement. A patient who just had a stent placed will need months before elective surgery is safe. The cardiologist’s job is to give the surgical and anesthesia teams the information they need to keep you as safe as possible, not to rubber-stamp the operation.

What Happens After Surgery

Cardiac clearance doesn’t end when you’re wheeled into the operating room. In high-risk patients, the cardiologist often stays involved postoperatively. One reason is a phenomenon called myocardial injury after noncardiac surgery, or MINS. About one in five patients who undergo major inpatient surgery shows elevated troponin levels afterward, indicating that heart muscle cells have been damaged. The vast majority of these events, over 90% in one large study, occur without any symptoms at all: no chest pain, no shortness of breath, nothing the patient would report.¹⁸

These silent injuries matter. MINS is independently and strongly associated with both short-term and long-term mortality even without symptoms, ECG changes, or imaging evidence of a heart attack.¹⁹ This is why routine troponin monitoring after surgery is increasingly recommended for high-risk patients. Without checking, these events simply go undetected. One recent review estimated MINS occurs in about 13% of adults aged 45 and older undergoing major inpatient surgery and emphasized that routine monitoring is needed to avoid missing the majority of cases.²⁰

Disparities in Who Gets the Full Evaluation

Not every patient headed for surgery gets the same cardiac workup, and the differences aren’t always medically justified. A retrospective study of patients undergoing bariatric surgery found that Black, Hispanic, and patients of other racial or ethnic minority groups were significantly less likely to undergo preoperative cardiovascular testing compared to White patients, even after adjusting for their cardiac risk scores. White patients also had shorter wait times to surgery.²¹ These findings point to systemic gaps in referral patterns that can leave some patients going into surgery with undetected cardiac risk. If you’re scheduled for a major operation and feel your heart history hasn’t been thoroughly reviewed, it’s reasonable to ask your surgeon or primary care doctor whether a cardiology consult is appropriate.

When the Evaluation Feels Like Too Much

One of the most common frustrations patients experience is the feeling that cardiac clearance is delaying a surgery they need. A hip fracture patient in pain, a cancer patient with a growing tumor, someone whose quality of life has cratered while waiting: the weeks of cardiac testing can feel like unnecessary red tape. And in some cases, they’re right to question it. Preoperative stress testing in low-risk patients doesn’t improve outcomes and can generate false alarms that cascade into cardiac catheterizations or delays that carry their own risks. The 2024 guidelines explicitly emphasize a stepwise approach: test only when the result will change management, not to cover legal bases or satisfy institutional checklists. If your cardiologist recommends a test, it’s fair to ask what would change depending on the result. If nothing would change, the test may not be worth the wait.