What is the interpretation of an electrocardiogram (ECG) showing a heart rate of 75 beats per minute, sinus rhythm, borderline prolonged PR interval, probable left atrial enlargement, left anterior fascicular block, intraventricular conduction delay (IVCD) with secondary repolarization abnormality, and signs of an old anterior myocardial infarct?

From the Guidelines

The patient's ECG shows a sinus rhythm with a heart rate of 75 beats per minute, and given the presence of a borderline prolonged PR interval, probable left atrial enlargement, left anterior fascicular block, and evidence of an old anterior myocardial infarction, further evaluation and management by a cardiologist is necessary to prevent potential morbidity and mortality. The ECG findings are consistent with significant cardiac pathology, including a prolonged PR interval greater than 212 milliseconds, which is defined as first-degree atrioventricular block according to the 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay 1. The left anterior fascicular block is also evident, characterized by a QRS duration less than 120 ms, frontal plane axis between 45 and 90 degrees, and a qR pattern in lead aVL.

The presence of probable left atrial enlargement, as indicated by a P wave duration greater than 50 milliseconds and negative terminal force in V1 greater than 0.10 mV, suggests increased pressure or volume in the left atrium, which can be a precursor to atrial fibrillation or other cardiac complications. The old anterior myocardial infarction is also a significant finding, as it can increase the risk of future cardiac events. The abnormal ST-T segments and QS pattern in leads V2-V5 further support the presence of cardiac pathology.

Given the complexity of these findings, it is essential to refer the patient to a cardiologist for further evaluation and management to improve quality of life and reduce the risk of morbidity and mortality. The cardiologist can perform additional tests, such as echocardiography or stress testing, to further assess cardiac function and determine the best course of treatment. According to the 2018 ACC/AHA/HRS guideline, patients with significant cardiac conduction abnormalities, such as those present in this patient, require careful evaluation and management to prevent adverse outcomes 1.

Key findings from the ECG include:

• Sinus rhythm with a heart rate of 75 beats per minute
• Borderline prolonged PR interval
• Probable left atrial enlargement
• Left anterior fascicular block
• Evidence of an old anterior myocardial infarction
• Abnormal ST-T segments and QS pattern in leads V2-V5.

These findings, in combination with the patient's clinical presentation, necessitate prompt referral to a cardiologist for further evaluation and management to prevent potential complications and improve quality of life. The 2018 ACC/AHA/HRS guideline provides a framework for the evaluation and management of patients with bradycardia and cardiac conduction delay, and adherence to these guidelines can help improve patient outcomes 1.

From the Research

ECG Interpretation

The provided ECG results indicate:

• A heart rate of 75 with sinus rhythm
• Borderline prolonged PR interval
• Probable left atrial enlargement
• Left anterior fascicular block
• IV with secondary repolarization abnormality
• Anterior infarct, old
• Normal P axis, V-rate 50-99
• PR >212, V-rate 50-90
• P >50ms, <-0.10mV in V1
• Axis (240,-40), initial forces infer
• Multi-IV criteria, abnormal ST-r
• -40ms, abnormal ST-T, V2-V5

Clinical Significance

According to 2, the ECG is a crucial tool in diagnosing and managing patients with acute coronary syndromes. The presence of ST segment elevation or depression can indicate acute occlusion of an epicardial artery or subendocardial ischemia. However, these findings can also be caused by non-ischemic etiologies.

Left Anterior Fascicular Block

The study by 3 discusses the electrocardiographic criteria for isolated left anterior fascicular block, which can decrease the voltage in chest leads and increase the voltage in limb leads. This condition can also mask or mimic infarction and left ventricular hypertrophy.

Prolonged PR Interval

The research by 4 suggests that a prolonged PR interval may be associated with adverse cardiovascular outcomes, including increased risk of mortality, heart failure, and atrial fibrillation.

ECG Interpretation in Clinical Practice

The studies by 5 and 6 highlight the importance of accurate ECG interpretation in clinical practice, particularly in acute care settings. However, these studies also reveal variability in nurses' competency in ECG interpretation, emphasizing the need for regular training and education to improve skills and confidence.

Key Findings

• ECG interpretation is crucial in diagnosing and managing patients with acute coronary syndromes 2
• Left anterior fascicular block can mask or mimic infarction and left ventricular hypertrophy 3
• Prolonged PR interval may be associated with adverse cardiovascular outcomes 4
• Nurses' competency in ECG interpretation varies, and regular training is recommended 5, 6