ECG and coronary artery illustration representing diagnostic accuracy and potential misdiagnosis.

Decoding ECG Anomalies: Simple Errors, Serious Consequences

Avery Sinclair in Health & Wellness June 2025 • 4 min read.

"A Closer Look at Limb Lead Reversal and Coronary Angiography Overtreatment"

In the fast-paced world of modern medicine, technology offers unprecedented diagnostic capabilities. However, even the most advanced tools are only as good as the professionals interpreting the data. This article delves into two critical issues highlighted in recent medical literature: errors in electrocardiogram (ECG) interpretation and the potential for overtreatment through coronary computed tomographic angiography (CCTA).

ECGs are a fundamental tool in assessing heart health, but simple errors such as limb lead reversal can lead to misdiagnoses with potentially severe consequences. Similarly, while CCTA offers detailed imaging of the coronary arteries, its overuse can result in unnecessary and potentially harmful interventions.

By examining these challenges, this article aims to raise awareness among healthcare providers and empower patients to advocate for informed and appropriate care. Understanding the nuances of ECG interpretation and the risks associated with over-reliance on advanced imaging is crucial for improving patient outcomes and reducing healthcare costs.

The Hidden Danger of Limb Lead Reversal

ECG and coronary artery illustration representing diagnostic accuracy and potential misdiagnosis.

One of the most alarming issues discussed in recent medical literature is the occurrence of limb lead reversal during electrocardiogram (ECG) testing. In a letter to the editor of JAMA Internal Medicine, Dr. Laszlo Littmann brought attention to a critical error in a published study by Abou Ziki and Rosenfeld. Dr. Littmann pointed out that one of the ECGs presented in the study likely had reversed limb leads, a seemingly minor mistake that can have significant diagnostic implications.

Limb lead reversal happens when the electrodes placed on the arms and legs are incorrectly positioned, leading to a distorted ECG reading. While this may seem like a trivial error, it can mimic serious cardiac conditions, leading to unnecessary anxiety, further testing, and potentially harmful interventions.

Misdiagnosis of Myocardial Ischemia: Limb lead reversal can create patterns that resemble myocardial ischemia or even infarction, leading to the false diagnosis of heart attack.
Unnecessary Interventions: Patients may undergo unnecessary stress tests, angiograms, or even be considered for procedures like angioplasty or bypass surgery based on a misinterpreted ECG.
Delayed Treatment: In some cases, the focus on the false diagnosis can delay the detection and treatment of the actual underlying condition.

Dr. Littmann emphasized that the telltale signs of limb lead reversal become more apparent when the ECG is enlarged, specifically pointing to a flat line in lead II as a key indicator. This occurs because the right arm lead, when placed on the right leg, records a minimal potential difference. Additionally, the presence of positive "retrograde" P waves in leads III and aVF, along with negative P waves in aVL, further supports the diagnosis of lead reversal. The original authors acknowledged the potential error but maintained that it did not detract from the main point of their study.

Prioritizing Prudent Care: A Call for Vigilance

The insights from these medical letters underscore the critical need for vigilance and careful consideration in medical practice. By addressing the potential pitfalls of ECG interpretation and the risks associated with advanced imaging techniques, this article advocates for a more balanced and thoughtful approach to patient care. Encouraging healthcare providers to remain diligent and patients to stay informed can ultimately lead to better outcomes and a more sustainable healthcare system.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

Everything You Need To Know

What is limb lead reversal, and what are the potential consequences if it goes undetected during an electrocardiogram (ECG) test?

Limb lead reversal occurs when the electrodes are incorrectly placed on the arms and legs during an electrocardiogram (ECG) test. This seemingly small error can lead to distorted ECG readings that mimic serious cardiac conditions. If not detected, limb lead reversal can result in misdiagnosis of myocardial ischemia or infarction, leading to unnecessary stress tests, angiograms, and potentially harmful interventions. In some instances, the focus on the false diagnosis caused by limb lead reversal can delay the detection and treatment of the actual underlying condition.

What are the key indicators that can help identify limb lead reversal on an ECG?

Key indicators of limb lead reversal include a flat line in lead II of the ECG, positive "retrograde" P waves in leads III and aVF, and negative P waves in aVL. Dr. Littmann emphasized these signs become more apparent when the ECG is enlarged. Spotting these telltale signs is crucial for avoiding misdiagnosis and unnecessary interventions.

What is coronary computed tomographic angiography (CCTA), and why should healthcare providers be cautious about its overuse?

Coronary computed tomographic angiography (CCTA) is a detailed imaging technique for the coronary arteries. While CCTA provides valuable information, its overuse can lead to overtreatment and potentially harmful interventions. The risk lies in the possibility of identifying minor anomalies that might not require aggressive treatment, leading to unnecessary procedures and increased healthcare costs.

How can misinterpreting an ECG, particularly due to limb lead reversal, lead to unnecessary interventions, and what are the broader implications of such errors?

Misinterpreting an ECG due to issues like limb lead reversal can lead to a cascade of unnecessary interventions. A false diagnosis of myocardial ischemia, for example, might prompt unnecessary stress tests, angiograms, angioplasty, or even bypass surgery. This not only exposes patients to potential risks associated with these procedures but also contributes to increased healthcare costs and patient anxiety. Vigilance in ECG interpretation is essential to prevent these consequences.

What does prioritizing prudent care entail in the context of ECG interpretation and advanced imaging techniques like coronary computed tomographic angiography (CCTA)?

Prioritizing prudent care involves vigilance in ECG interpretation to avoid errors like limb lead reversal. It also means a thoughtful approach to advanced imaging techniques like coronary computed tomographic angiography (CCTA) to prevent overtreatment. Healthcare providers should remain diligent and patients should stay informed to promote better outcomes and a more sustainable healthcare system, balancing the benefits of technology with careful clinical judgment.