Guidelines for Optimal ECG Performance
The optimal performance of electrocardiography (ECG) requires adherence to standardized procedures for specific clinical scenarios, with indications determined by the patient's clinical status and cardiovascular risk factors. 1
Indications for ECG Performance
Baseline/Initial Evaluation
- ECG is an integral part of initial evaluation for all patients with known or suspected cardiovascular disease 1
- Cardiac abnormalities may be suspected based on symptoms, abnormal physical findings, previous abnormal ECGs, or other abnormal laboratory studies 1
Response to Therapy
- ECGs should be performed in patients receiving treatments known to produce ECG changes that correlate with therapeutic responses or disease progression 1
- ECGs are indicated when prescribed therapy may produce adverse effects detectable by ECG changes 1
- Serial ECGs are appropriate after:
- Initiation of drug therapy
- Changes in therapy
- Addition of drugs that may interact and have cardiac effects 1
Follow-up Monitoring
- Follow-up ECGs should be determined based on:
- Changes in symptoms
- Physical signs
- Growth or maturation (in infants/children)
- Laboratory findings 1
- Specific symptoms warranting repeat ECG include:
- Syncope and near-syncope
- Unexplained changes in angina pattern
- New or worsening dyspnea
- Extreme fatigue, weakness, or prostration
- Palpitations 1
Preoperative Evaluation
- A recent preoperative ECG is recommended for patients with known cardiovascular disease undergoing cardiac or noncardiac surgery 1
- Class I indication (strongly recommended): All patients with known cardiovascular disease or dysfunction 1
- Class II indication (reasonable): Patients with hemodynamically insignificant heart disease, mild hypertension, or infrequent premature complexes 1
Special Clinical Scenarios
Pacemaker Monitoring
- 12-lead ECG is indicated:
- Soon after pacemaker insertion or revision
- Whenever pacemaker malfunction is suspected
- After lead threshold maturation
- At periodic intervals throughout the lifetime of the device 1
- More frequent ECGs are indicated with atrial or dual-chamber pacing systems due to difficulty detecting atrial lead malfunction 1
Post-Procedural Monitoring
- Patients undergoing electrical or pharmacologic cardioversion should have ECGs:
- Just before the procedure
- Immediately after the procedure
- Before hospital discharge 1
- After cardiac or extensive pulmonary surgery, serial ECGs are recommended until the condition stabilizes and before discharge 1
Technical Considerations
- Proper electrode placement is critical for accurate ECG interpretation, with studies showing high levels of placement variation among healthcare providers 2
- Standardized lead configurations are important to avoid misdiagnosis from serial comparisons between modified and standard lead configurations 3
- Body position changes can cause QRS and ST-T changes that may trigger false alarms, requiring correction techniques 4
- New standards for ECG equipment are being developed to harmonize requirements and testing methods across different types of ECG devices 5
Common Pitfalls to Avoid
- Incorrect chest electrode placement can significantly alter ECG morphology 2
- Failure to account for body position changes when interpreting ECG changes 4
- Using non-standardized lead configurations that produce waveforms different from standard 12-lead ECG 3
- Performing unnecessary ECGs in patients receiving therapy not known to produce ECG changes 1
- Overlooking the importance of ECG in early disease identification, such as in hypertrophic cardiomyopathy where an abnormal ECG may be the only early manifestation 6