The issue
An abnormal EKG result can be a shock to the system. Dr. Samir Saba, co-director of the UPMC Heart and Vascular Institute and chief of the Division of Cardiology at the University of Pittsburgh School of Medicine, is here to help ground you in knowledge.
Q: What does the process look like when getting an EKG?
A: An EKG is quick and noninvasive. Acquiring an EKG reading entails placing small adhesive electrodes on the chest, arms and legs to record electrical signals. The test typically takes a few minutes, during which time the patient simply lies still and breathes normally. It is completely painless since there is no electricity delivered to your body, but only passive recording.
Q: How do EKGs work?
A: EKGs detect the tiny electrical currents generated by heart muscle cells as they depolarize (leading to muscle contraction) and repolarize (leading to muscle relaxation) with each heartbeat.
Electrodes on the skin capture these signals from different angles corresponding to the 12 leads of the EKG, allowing a global view of the heart’s electrical activity. The EKG machine amplifies and displays these signals as waveforms on paper or a screen.
By analyzing the timing and shape of these waveforms, clinicians can detect potential abnormalities.
Q: What types of things can be signified by an EKG result?
A: An EKG or ECG (electrocardiogram) reflects the heart’s electrical activity and can identify abnormalities in cardiac rhythm (aka arrhythmias), heart rate and electrical conduction pathways.
It can suggest prior or ongoing heart muscle injury, such as a heart attack, enlargement of heart chambers or strain patterns often related to high blood pressure or valve disease. Electrolyte imbalances and certain medication effects can also leave recognizable electrical signatures on the EKG.
An EKG provides detailed information on heart rate, rhythm regularity, timing intervals and electrical axis. It also shows waveform morphology, which can indicate ischemia (a medical condition where blood flow is restricted or reduced) or prior myocardial infarction. These features not only help clinicians identify problems within the heart’s electrical system but also infer structural or metabolic abnormalities.
While a powerful screening tool that has been available for more than a hundred years, EKGs remain a 10-second snapshot in time. Changes over time from one EKG to the next are particularly informative in identifying new problems.
Q: What among those issues are worthy of getting worried about?
A: Many EKG findings are benign or incidental, including mild rhythm variations, nonspecific changes in parts of the cardiac waveform or normal variants seen in healthy individuals.
Other EKG findings signal clinically important issues, like significant arrhythmias, evidence of ischemia or conduction blocks. In these instances, context matters greatly, as the same finding may be trivial in one person and meaningful in another, depending on symptoms and medical history.
In practice, most abnormalities prompt clarification rather than alarm, and only a minority should trigger urgency or emergency.
Q: What percentage of EKGs necessitate a follow-up?
A: A majority of EKGs are either normal or show findings that do not require further testing. The proportion of EKGs that may prompt some form of follow-up varies by population, with higher rates in older or symptomatic patients.
Only a small fraction represents urgent or dangerous conditions requiring immediate action, but again, this is very variable and depends on the clinical context.
Q: What are typically the next steps if something necessitates further evaluation?
A: The next step depends on the abnormality and clinical context but often includes confirming the finding and assessing the patient’s symptoms.
Common follow-up testing includes blood work (e.g., cardiac enzymes or electrolyte levels), longer ambulatory rhythm monitoring, such as using a Holter or event monitor, echocardiography to evaluate the structure and function of the heart, or stress testing to assess for the presence of blockages in the arteries of the heart.
In many cases, advanced imaging or referral to a general cardiologist or cardiac electrophysiologist is appropriate. Urgent findings, such as a suspected acute heart attack, require immediate evaluation in an emergency room setting.