There can be a number of causes for a borderline electrocardiogram (ECG), a study of electrical activity in the heart. When an ECG is borderline, it means that some anomalies are present and the doctor needs to evaluate the patient to determine whether they are of significance. Patients should not panic if they have a borderline ECG result because there can be many reasons for this, and it is not necessarily dangerous.
In a borderline ECG, some of the readings do not look quite right, but they are not pushed into the margin where they are an immediate cause for concern. Sometimes, this occurs simply because a patient was stressed out or worried. Many patients are nervous before an ECG, and this can cause small variations in their heart rates that may appear on the test. The doctor might discard the results if the patient appeared especially worried, and request a new test to see if more accurate values can be obtained.
Another reason for a borderline ECG is improper procedure during the test. Sometimes the electrodes are not placed correctly or there is something wrong with the machine and the reading is off. Patients with large breasts or significant deposits of fat in their chests are more likely to have a borderline ECG because it is harder to place the electrodes. The technician may spot the problem if she has access to a real-time readout, and may halt the test to reposition and get a better reading.
A borderline ECG can also occur when a patient does have a genuine anomaly, but it is minor. The test will show small variations in the heart rhythm and function, but they are not significant enough to be a cause for concern. If a patient has a borderline ECG, the doctor might recommend testing again in the future to monitor the issue. Otherwise, the doctor may simply note the finding in the patient's chart so it will be available for future reference.
Patients should be aware that ECG equipment often marks up the printout with notations like “borderline” on the basis of stored algorithms. The equipment is sometimes wrong, because it does not account for patient history and other factors. A doctor can review the test result and determine whether it is significant. If it is, he will recommend some additional testing to learn more about the patient's situation. When it is not, the doctor will assure the patient that it is not anything he needs to worry about.