From the Guidelines
Examples of EKG readings include normal sinus rhythm, atrial fibrillation, ventricular tachycardia, ST-segment elevation myocardial infarction (STEMI), and heart blocks, among others, which are crucial for diagnosing cardiac conditions and guiding treatment decisions, as noted in the 2011 ACCF/AHA focused update incorporated into the ACC/AHA 2007 guidelines for the management of patients with unstable angina/non-ST-elevation myocardial infarction 1.
Key EKG Findings
- Normal sinus rhythm: regular P waves followed by QRS complexes at 60-100 beats per minute
- Atrial fibrillation: irregular rhythm and absence of P waves
- Ventricular tachycardia: wide QRS complexes at rates exceeding 100 beats per minute
- ST-segment elevation myocardial infarction (STEMI): elevated ST segments indicating heart attack
- Heart blocks: delayed or blocked electrical impulses between the atria and ventricles
Importance of EKG Interpretation
EKGs are interpreted by examining rate, rhythm, axis, intervals (PR, QRS, QT), and waveform morphology, as discussed in the practice standards for electrocardiographic monitoring in hospital settings 1. Understanding these patterns is crucial for diagnosing cardiac conditions, as each abnormality reflects specific electrical disturbances in the heart. For example, ST elevation typically indicates myocardial injury due to blocked coronary arteries, while irregular rhythms without P waves suggest atrial fibrillation caused by chaotic electrical activity in the atria.
Clinical Application
The ECG is a critical tool in the diagnosis and management of cardiac conditions, and its interpretation should be guided by the most recent and highest-quality evidence, such as the 2011 ACCF/AHA focused update 1 and the practice standards for electrocardiographic monitoring in hospital settings 1. By recognizing and understanding the various EKG patterns and abnormalities, healthcare providers can make informed decisions about patient care and treatment, ultimately improving outcomes and reducing morbidity and mortality.
From the Research
EKG Readings Examples
- ST segment elevation in patients with active symptoms usually indicates acute occlusion of an epicardial artery with ongoing transmural ischemia 2
- ST depression in leads V1-V3 can indicate subendocardial ischemia secondary to subocclusion of the epicardial artery, distal embolization to small arteries or spasm supply/demand mismatch 2
- ST depression in leads other than V1-V3 can be indicative of subendocardial ischemia secondary to subocclusion of the epicardial artery, distal embolization to small arteries or spasm supply/demand mismatch 2
- Exercise-induced ischemic ST-segment depression can be a marker for risk stratification in patients with suspected or known coronary artery disease 3
- ST-segment elevation in lead aVR can be a marker for risk stratification in patients with suspected or known coronary artery disease 3
- Abnormal heart rate recovery post-exercise, failure to achieve target heart rate, and poor exercise capacity can improve risk stratification of ExECG 3
Clinical Significance
- EKG readings should be interpreted along with the clinical assessment of the patient 2
- Comparison to previous ECG and subsequent ECGs can add to the diagnosis and interpretation in difficult cases 2
- Optimal test selection for symptomatic patients with suspected coronary artery disease requires a patient-centered approach factoring in the risk/benefit ratio and cost-effectiveness 3