Indications for Electrocardiogram (EKG)
An electrocardiogram (EKG) is warranted for patients with known cardiovascular disease, those with symptoms suggestive of cardiovascular disease, before surgery in patients with cardiovascular risk factors, and when monitoring response to certain therapies. 1
Clinical Scenarios Where EKG is Indicated
Known Cardiovascular Disease
- EKG is a first-line test for patients with known cardiovascular disease, including those with coronary artery disease, heart failure, arrhythmias, or conduction abnormalities 1
- Serial EKGs are recommended to monitor disease progression or response to therapy in patients with established cardiovascular conditions 1
- Patients with implanted cardiac devices (pacemakers, defibrillators) should have periodic EKGs to assess device function 1
Symptoms Suggestive of Cardiovascular Disease
- EKG is indicated for patients presenting with chest pain, dizziness, syncope, or near-syncope 1
- Patients with palpitations, unexplained dyspnea, extreme fatigue, or changes in angina pattern should undergo EKG evaluation 1
- Syncope evaluation should always include an EKG as it may identify arrhythmias or conduction abnormalities that could explain the episode 2
Preoperative Assessment
- EKG is recommended for patients with known cardiovascular disease, peripheral vascular disease, or cerebrovascular disease who are undergoing intermediate or high-risk surgery 1
- Patients with one or more clinical risk factors (coronary artery disease, heart failure, cerebrovascular disease, diabetes mellitus, renal insufficiency) should have an EKG before vascular surgery 1
- Patients older than 65 years should have a preoperative EKG regardless of the type of surgery 1
Medication Monitoring
- EKG is indicated before and during therapy with medications known to affect cardiac conduction or repolarization 1
- Common medications requiring EKG monitoring include:
- Psychotropic agents (phenothiazines, tricyclic antidepressants)
- Anti-infective agents (erythromycin, pentamidine)
- Antihypertensive medications
- Antiarrhythmic drugs
- Digitalis and other heart failure medications 1
When EKG is Not Indicated
- Asymptomatic patients undergoing low-risk surgery with no cardiovascular risk factors 1
- Patients receiving medications not known to produce EKG changes 1
- Routine screening of asymptomatic individuals without cardiovascular risk factors 3
Diagnostic Value of EKG
- A normal EKG is rare in patients with heart failure (<2% of cases) and has high negative predictive value for major structural heart disease 4
- Specific EKG findings like QRS width ≥120 ms or anterior pathological Q-waves indicate high probability of major structural heart disease 4
- In patients with suspected syncope, an EKG can identify the cause in approximately 7% of cases, avoiding further evaluations 2
Pitfalls and Caveats
- Computer-interpreted EKGs can contain errors and should always be reviewed by a qualified physician 3
- A normal EKG does not completely exclude cardiac disease, particularly in early stages of conditions like hypertrophic cardiomyopathy 5
- The absence of acute changes on a single EKG does not rule out evolving cardiac conditions, and serial EKGs may be necessary 1
- Continuous cardiac monitoring (telemetry) provides different information than a standard 12-lead EKG and should not be considered equivalent 1
In conclusion, the decision to perform an EKG should be based on the presence of cardiovascular disease, symptoms, preoperative risk assessment, and medication monitoring requirements. Following these evidence-based guidelines will ensure appropriate use of this valuable diagnostic tool while avoiding unnecessary testing.