From the Guidelines
In patients with chest pain or other symptoms suggestive of acute coronary syndrome (ACS), a 12-lead electrocardiogram (ECG) should be performed and evaluated for ischemic changes within 10 minutes of the patient’s arrival at an emergency facility. This is based on the recommendation from the 2014 AHA/ACC guideline for the management of patients with non-ST-elevation acute coronary syndromes 1.
When interpreting EKG readings, clinicians look for abnormalities such as:
- Arrhythmias (irregular rhythms)
- Conduction blocks
- Signs of ischemia (ST segment changes)
- Hypertrophy (enlarged chambers)
- Evidence of previous heart attacks (Q waves) Common abnormal findings include:
- Atrial fibrillation (irregular rhythm without P waves)
- Ventricular tachycardia (rapid wide QRS complexes)
- Heart blocks (delayed conduction)
- ST elevation (potential heart attack)
The presence of ST-segment elevation has been shown to be the most sensitive and specific ECG marker for acute myocardial infarction, usually appearing within minutes after the onset of symptoms 1. However, only 30-40% of patients with acute chest pain who develop acute myocardial infarction initially have ST-elevations on the hospital admission ECG.
If the initial ECG is not diagnostic but the patient remains symptomatic and there is a high clinical suspicion for ACS, serial ECGs (e.g., 15- to 30-minute intervals during the first hour) should be performed to detect ischemic changes 1. Additionally, serial cardiac troponin I or T levels should be obtained at presentation and 3 to 6 hours after symptom onset to identify patients with ACS.
EKGs are essential diagnostic tools because they provide immediate information about heart function, helping clinicians quickly identify life-threatening conditions that require immediate intervention. The test is non-invasive, painless, and provides valuable information about the heart's electrical system that other tests cannot capture as efficiently.
From the Research
EKG Readings in Cardiac Arrhythmias
- EKG readings are crucial in diagnosing and managing cardiac arrhythmias, particularly in patients with acute coronary syndromes 2
- The main common dominant mechanisms of arrhythmias in ischemia are intramural re-entry and triggered activity in reperfusion 2
- Atrial arrhythmias, such as atrial fibrillation, can be treated with antiarrhythmic drug therapy, including beta-blockers or amiodarone, and direct current cardioversion 2
- Ventricular arrhythmias, including premature ventricular complexes, accelerated idioventricular rhythm, and sustained ventricular tachycardia, can be treated with antiarrhythmic drug therapy, implantable cardioverter defibrillator therapy, radiofrequency catheter ablation, and stellate ganglion blockade 2
Relationship between EKG Readings and Antithrombotic Therapy
- Antithrombotic agents, including antiplatelet drugs and anticoagulants, are used to reduce mortality and morbidity in acute coronary syndromes 3
- Aspirin is the foundation antiplatelet agent, and new P2Y12 receptor inhibitors, such as prasugrel and ticagrelor, have clear benefits compared with clopidogrel for dual antiplatelet therapy 3
- EKG readings can help identify patients who may benefit from antithrombotic therapy, particularly those with atrial fibrillation or other cardiac arrhythmias 3
EKG Readings in Acute Coronary Syndrome
- Acute coronary syndrome is characterized by a high incidence of serious adverse outcomes, including death, acute myocardial infarction, or refractory angina requiring emergency revascularisation 4
- EKG readings are essential in diagnosing and managing acute coronary syndrome, particularly in identifying patients with ST-elevation myocardial infarction or non-ST elevation myocardial infarction 4
- Beta-blockers, such as those used in the treatment of cardiac arrhythmias, have been shown to be effective in reducing mortality and morbidity in patients with acute coronary syndrome 5
EKG Readings in Cardiovascular Disease
- Chest pain and shortness of breath are common symptoms in patients with cardiovascular disease, and EKG readings can help identify underlying cardiac arrhythmias or other conditions 6
- EKG readings can be used to monitor patients with cardiovascular disease and identify those who may be at risk of adverse outcomes, such as cardiac arrhythmias or myocardial infarction 6