Surreal illustration of a heart with a partially blocked electrical grid.

Unlocking Heart Health: How a Hidden Blockage Mimics Angina

Soraya Malik in Health & Wellness December 2025 • 4 min read.

"Learn how transient left septal fascicular block can cause stable angina symptoms, and the critical role of early diagnosis."

Chest pain is a scary thing, often making us think of heart attacks. But what if the discomfort you're feeling isn't a heart attack but a different kind of heart issue mimicking those symptoms? Stable angina, characterized by predictable chest pain during exertion, can sometimes have an unexpected culprit: a transient left septal fascicular block.

A recent study published in the 'Journal of Electrocardiology' sheds light on this phenomenon, detailing a case where a patient's angina-like symptoms were caused by a temporary blockage in a specific part of the heart's electrical system. This case highlights the crucial role of careful diagnosis and advanced cardiac imaging in uncovering hidden heart problems.

This article will break down this complex case, explaining what a left septal fascicular block is, how it can mimic angina, and why early detection and treatment are essential for protecting your heart health. We'll explore the subtle clues in an ECG (electrocardiogram) that can point to this condition and the life-saving potential of timely intervention.

The Case: When Angina Isn't Always What It Seems

Surreal illustration of a heart with a partially blocked electrical grid.

Imagine a 56-year-old man experiencing chest pain during exercise. He describes it as oppressive, occurring for about 20 days, and of short duration – classic symptoms of stable angina. He has a history of smoking and a family history of heart problems. An initial ECG reveals a left anterior fascicular block (LAFB), a common condition. However, a closer look, prompted by persistent symptoms, reveals something more complex.

A second ECG unveils a qRs pattern with tall R waves and prominent anterior QRS forces (PAFs). This unusual combination, along with an extreme left SÂQRS deviation, suggests something beyond typical LAFB. Specifically, it indicates a potential problem with the heart's first septal vector of ventricular activation.

Here's what made this case unique:

The patient's symptoms: Stable angina-like chest pain.
ECG findings:
- Initial LAFB
- Later development of qRs pattern with tall R waves and prominent anterior QRS forces (PAFs)
- Extreme left SÂQRS deviation.
The key question: Was this simply angina, or something more?

Considering the patient's symptoms and the unusual ECG findings, doctors suspected a critical proximal obstruction in the left anterior descending coronary artery (LAD). A coronary angiography confirmed their suspicion, revealing a blockage in the LAD before its first septal perforator branch.

Decoding Your Heart: The Importance of Early Detection

This case underscores the importance of recognizing that not all chest pain is the same. While stable angina is a common condition, unusual ECG patterns and persistent symptoms should prompt further investigation. A transient left septal fascicular block, while rare, can mimic angina and signal a more serious underlying problem.

The good news is that with prompt diagnosis and intervention, such as percutaneous coronary intervention (PCI), the blockage can be resolved, and the heart's electrical system can return to normal. In the presented case, after PCI, the left bifascicular block (LSFB+LAFB) disappeared, and the patient's ECG returned to a normal pattern.

If you're experiencing chest pain, especially during exertion, don't ignore it. Talk to your doctor and ensure a thorough evaluation, including an ECG. Early detection and treatment can make all the difference in protecting your heart health and ensuring a long and active life.

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.

This article is based on research published under:

DOI-LINK: 10.1016/j.jelectrocard.2018.11.004, Alternate LINK

Title: Transient Left Septal Fascicular Block In A Patient With Stable Effort Angina And Critical Proximal Obstruction Of Left Anterior Descending Coronary Artery

Subject: Cardiology and Cardiovascular Medicine

Journal: Journal of Electrocardiology

Publisher: Elsevier BV

Authors: Andrés Ricardo Pérez-Riera, Raimundo Barbosa-Barros, Rodrigo Daminello-Raimundo, Luiz Carlos De Abreu, Kjell Nikus

Published: 2019-01-01

Everything You Need To Know

What is a transient left septal fascicular block, and how can it be mistaken for stable angina?

A transient left septal fascicular block involves a temporary interruption in the electrical signals within the heart. This can manifest with symptoms that closely resemble stable angina. The ECG can provide clues, such as a qRs pattern with tall R waves and prominent anterior QRS forces along with an extreme left SÂQRS deviation, suggesting a problem with the heart's first septal vector of ventricular activation.

What specific ECG findings might suggest a transient left septal fascicular block rather than just typical stable angina?

The initial ECG showed a left anterior fascicular block (LAFB). However, a subsequent ECG revealed a qRs pattern with tall R waves and prominent anterior QRS forces (PAFs), along with an extreme left SÂQRS deviation. These findings pointed towards a potential issue beyond a typical LAFB, specifically affecting the heart's first septal vector of ventricular activation.

How does a coronary angiography help in diagnosing a transient left septal fascicular block, and what might it reveal?

A coronary angiography is a crucial diagnostic tool. In the case described, the coronary angiography revealed a blockage in the left anterior descending coronary artery (LAD) before its first septal perforator branch. This blockage was the underlying cause of the transient left septal fascicular block.

Why is early detection of a transient left septal fascicular block so important, and what are the potential implications of missing this diagnosis?

Early detection is crucial because a transient left septal fascicular block can mimic stable angina but be caused by a more serious underlying issue, such as a blockage in the left anterior descending coronary artery (LAD). Failure to identify and address this blockage can lead to potential heart damage. Recognizing subtle ECG changes and pursuing further investigation with coronary angiography can lead to timely intervention and improved outcomes.

How was stable angina initially diagnosed, and what prompted doctors to suspect a transient left septal fascicular block instead?

The initial diagnosis was stable angina based on the patient's symptoms, which included chest pain during exercise. The first ECG showed a left anterior fascicular block. However, the persistence of symptoms and the unusual ECG pattern on the second ECG prompted further investigation that eventually revealed the transient left septal fascicular block. This highlights the importance of considering alternative diagnoses when symptoms don't fully align with initial findings or persist despite treatment.