Stress test results combine several measurements to assess how well your heart handles physical demand. The key numbers to look at are your exercise capacity in METs, how high your heart rate climbed, what happened to your blood pressure, and whether the electrical tracings of your heart showed signs of reduced blood flow. If you had a nuclear or echo stress test, your results will also include imaging findings. Here’s how to make sense of each piece.
Exercise Capacity in METs
Your report will list how many METs you achieved. One MET represents the energy your body uses sitting still. The more METs you reach, the better your cardiovascular fitness. Less than 5 METs is considered poor, 5 to 8 is fair, 9 to 11 is good, and 12 or more is excellent. This single number is one of the strongest predictors of long-term survival, sometimes more telling than the electrical findings themselves. If you scored below 5, your doctor may recommend additional imaging to get a clearer picture of your heart’s blood supply.
Target Heart Rate and What It Means
Your age-predicted maximum heart rate is calculated as 220 minus your age. A 55-year-old, for example, has a predicted max of 165 beats per minute. For the test to be considered diagnostically useful, you generally need to reach at least 85% of that number. In this example, that’s about 140 bpm.
If you stopped short of 85%, your results may be labeled “non-diagnostic” or “submaximal.” That doesn’t mean something is wrong with your heart. It means the test didn’t push your heart hard enough to reliably rule out problems, and a negative result at low effort could be a false negative. Your doctor may want to repeat the test or order a stress imaging study instead.
On the other end, if your heart rate failed to rise appropriately despite strong effort, your report might mention chronotropic incompetence. This means your heart couldn’t speed up to match your body’s demand for oxygen. Providers typically flag this when your heart rate stays below 70% to 85% of your age-predicted max at peak exertion. Chronotropic incompetence can cause exercise fatigue and is itself linked to higher cardiovascular risk.
ST-Segment Changes on the EKG
The most closely watched part of a standard treadmill stress test is the ST segment, a small flat section of each heartbeat on the EKG tracing. When heart muscle isn’t getting enough blood during exercise, that segment shifts downward. A test is considered abnormal (positive for ischemia) when the ST segment drops by 1 millimeter or more in a horizontal or downsloping pattern. If the depression slopes upward, the result is usually reported as “equivocal,” meaning borderline and harder to interpret.
ST-segment elevation of more than 1 millimeter during the test is a more serious finding and is actually one of the reasons a technician would stop the test immediately. If your report mentions ST depression, note how many millimeters it was and in which leads (areas of the heart) it appeared. Deeper depression across more leads suggests more extensive blood flow limitation.
Keep in mind that a standard exercise EKG has a pooled sensitivity of about 68% and specificity of about 77% for detecting coronary artery disease. In practical terms, that means roughly one-third of people with real blockages can have a normal-looking test, and about one-quarter of positive results turn out to be false alarms. This is why doctors often pair the EKG with imaging when the clinical picture is unclear.
Blood Pressure During the Test
Your blood pressure naturally rises during exercise, and the report will show readings taken at each stage. A normal response is a steady climb in systolic pressure (the top number) with the diastolic pressure (bottom number) staying roughly stable or dropping slightly.
Two patterns stand out as abnormal. An exaggerated blood pressure response, defined as systolic pressure exceeding 210 mmHg in men or 190 mmHg in women, may signal underlying hypertension or stiff arteries even if your resting pressure looks fine. A drop in systolic pressure during increasing exercise is the opposite concern and can indicate severe coronary disease or a heart muscle that’s struggling to pump harder. Either finding will typically prompt further evaluation.
The Duke Treadmill Score
Many reports for standard treadmill tests include the Duke Treadmill Score, which rolls your exercise time, ST-segment changes, and any chest pain during the test into a single risk number. The formula is: exercise time in minutes, minus five times the maximum ST depression in millimeters, minus four times an angina index (0 if no chest pain, 1 if chest pain occurred, 2 if chest pain was the reason you stopped).
A score of 5 or higher places you in the low-risk category, meaning a very low annual risk of a major cardiac event. Scores between negative 11 and positive 5 fall into moderate risk. A score of negative 11 or lower is high risk, and those patients are typically referred for further testing such as a cardiac catheterization. If your report includes this score, it gives you a quick summary of where the overall picture lands.
Nuclear Stress Test: Perfusion Images
If you had a nuclear stress test, a radioactive tracer was injected into your bloodstream so a camera could capture images of blood flow through your heart muscle, both during stress and at rest. Your report will describe whether each region of the heart received normal tracer uptake or showed a “perfusion defect.”
The critical distinction is between reversible and fixed defects. A reversible defect appears during the stress images but fills in normally on the rest images. This pattern means the area is alive and healthy at rest but isn’t getting enough blood when the heart works harder, which points to a significant narrowing in the artery supplying that region. A fixed defect looks the same on both stress and rest images, meaning the area never lights up normally. A severe fixed defect usually represents scar tissue from a prior heart attack. However, a mild or moderate fixed defect can sometimes indicate muscle that is still alive but “hibernating” due to chronically reduced blood flow, which may benefit from treatment to restore circulation.
Your report may also comment on left ventricular size and function. If the heart chamber appears enlarged after stress compared to rest, or if the ejection fraction (the percentage of blood pumped out with each beat) drops during exercise, those are additional red flags for extensive coronary disease.
Stress Echo: Wall Motion Findings
A stress echocardiogram uses ultrasound to watch your heart walls contract before and immediately after exercise (or during medication-induced stress). The normal response is for the heart to squeeze more vigorously and actually become slightly smaller at peak stress, with each wall segment thickening evenly.
If a segment isn’t contracting properly, the report grades it on a four-point scale. Normal motion scores a 1. Hypokinetic (reduced movement) scores a 2 and suggests that part of the muscle isn’t getting full blood supply. Akinetic (no movement) scores a 3 and typically means more severe ischemia or prior damage. Dyskinetic (bulging outward when it should squeeze inward) scores a 4 and points to significant scarring or acute ischemia.
What matters most is whether these wall motion abnormalities are new. If a segment contracts normally at rest but becomes hypokinetic or akinetic during stress, that’s a strong indicator of a flow-limiting blockage in the artery feeding that region. If the abnormality is present at rest and doesn’t change, it more likely reflects old damage.
Putting the Pieces Together
No single number on a stress test tells the full story. A high MET level with no ST changes and a normal heart rate response is reassuring. Poor exercise capacity combined with ST depression, chest pain, and a dropping blood pressure is a much more concerning pattern. The Duke Treadmill Score exists precisely to combine these variables into one risk estimate, but your cardiologist will also weigh your symptoms, risk factors, and any imaging findings.
If your test was labeled “normal” or “negative,” it means no significant evidence of reduced blood flow was found at the level of exertion you achieved. If it was “positive” or “abnormal,” it means one or more findings suggest a blood flow problem worth investigating further, often with coronary imaging or catheterization. An “equivocal” or “inconclusive” result sits in between and usually leads to additional testing rather than a definitive answer.