Heart with a maze inside the left atrial appendage, symbolizing complexity and risk.

Silent Strokes: Is Your Heart's Shape Putting You at Risk?

Lena Voss in Health & Wellness July 2025 • 4 min read.

"New research uncovers how the structure of a small pouch in the heart may be a hidden culprit in unexplained strokes, urging a closer look at heart health."

Ischemic strokes are a major health concern, but what happens when the cause of a stroke remains a mystery? Cryptogenic strokes, defined as strokes with no identifiable cause, account for a significant percentage of all ischemic strokes. While atrial fibrillation (AF) is often suspected, it doesn't explain all cases. This leaves doctors and patients searching for answers.

New research is shedding light on a surprising factor that may contribute to these unexplained strokes: the shape of the left atrial appendage (LAA), a small pouch in the heart. The LAA's structure may influence the occurrence of thromboembolic events.

A recent study explored the role of LAA morphology in stroke patients, categorizing LAA shapes as either simple (chicken-wing) or complex (non-chicken-wing). The findings suggest a link between complex LAA shapes and cryptogenic strokes, offering new insights into stroke risk.

Decoding the Heart's Hidden Chambers: What's LAA Morphology?

Heart with a maze inside the left atrial appendage, symbolizing complexity and risk.

The left atrial appendage (LAA) is a small, ear-shaped pouch that extends from the left atrium of the heart. While seemingly insignificant, the LAA plays a crucial role in heart function. It is also a common site for blood clot formation, especially in individuals with atrial fibrillation. Clots that form in the LAA can break loose and travel to the brain, causing a stroke.

Traditionally, LAA morphology has been classified into four main types:

Chicken Wing: Characterized by a single lobe with a distinct bend, resembling a chicken wing.
Cactus: Features multiple lobes extending in different directions, resembling a cactus.
Windsock: A long, slender shape similar to a windsock.
Cauliflower: A more complex, multi-lobed shape resembling a cauliflower.

However, a new functional classification simplifies this further, categorizing LAA shapes into 'simple' (typically chicken-wing) and 'complex' (including all other morphologies, especially those with multiple lobes or significant internal structures). This simplification is based on the idea that complex shapes may promote blood stasis and clot formation, increasing stroke risk. In the study, complex LAA morphology, especially cauliflower-like structures, showed a higher risk of stroke due to poor emptying and slow filling, which creates turbulence. A higher left atrial volume index can be related to increased risk for stroke as well.

Looking Ahead: What Does This Mean for Stroke Prevention?

This study suggests that LAA morphology could be an independent risk factor for cryptogenic strokes, opening new avenues for stroke prevention. While more research is needed, these findings highlight the importance of assessing LAA morphology in individuals at risk of stroke. This information could help doctors tailor treatment plans and identify those who might benefit from more aggressive stroke prevention strategies, such as anticoagulation or LAA closure devices.

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: 10.3389/fcvm.2018.00131, Alternate LINK

Title: Complex Left Atrial Appendage Morphology Is An Independent Risk Factor For Cryptogenic Ischemic Stroke

Subject: Cardiology and Cardiovascular Medicine

Journal: Frontiers in Cardiovascular Medicine

Publisher: Frontiers Media SA

Authors: Indranill Basu-Ray, Deepthi Sudhakar, Gregory Schwing, Dominique Monlezun, Lucy Zhang, Sumit K. Shah, Deep Pujara, Kevin Ting, Nidal Abi Rafeh, Gholam Ali, Mark Cassidy, Kenneth Ellenbogen, Glen Levine, Wilson Lam, Nilesh Mathuria, Mohammad Saeed, Jared Bunch, Sheryl Martin-Schild, Michael Gold, Arash Aryana, Mehdi Razavi, Abdi Rasekh

Published: 2018-10-23

Everything You Need To Know

What exactly are cryptogenic strokes, and why are they so concerning?

Cryptogenic strokes are ischemic strokes where the cause cannot be identified despite thorough investigation. They are concerning because the lack of a clear cause makes it difficult to implement targeted prevention strategies. While conditions like atrial fibrillation (AF) are often suspected, they don't explain all cryptogenic strokes, leaving both doctors and patients without definitive answers.

How does the shape of the left atrial appendage (LAA) influence stroke risk?

The left atrial appendage's (LAA) morphology is believed to influence stroke risk due to its impact on blood flow. Complex LAA shapes, such as those classified as 'non-chicken-wing', can promote blood stasis and clot formation, potentially leading to thromboembolic events. Poor emptying and slow filling, seen particularly in cauliflower-like LAA structures, create turbulence, increasing the risk of clot formation that can then travel to the brain and cause a stroke. A higher left atrial volume index can be related to increased risk for stroke as well.

What are the different classifications of LAA morphology, and how is the new functional classification different?

Traditionally, LAA morphology has been classified into four main types: Chicken Wing, Cactus, Windsock, and Cauliflower. Chicken Wing is characterized by a single lobe with a distinct bend. Cactus features multiple lobes extending in different directions. Windsock is a long, slender shape. Cauliflower is a more complex, multi-lobed shape. The new functional classification simplifies this by categorizing LAA shapes into 'simple' (typically chicken-wing) and 'complex' (including all other morphologies). This simplification focuses on the functional implications of shape, with complex shapes believed to promote blood stasis and clot formation, increasing stroke risk.

What implications does the link between LAA morphology and cryptogenic strokes have for stroke prevention strategies?

The discovery that LAA morphology is an independent risk factor for cryptogenic strokes opens new avenues for stroke prevention. Assessing LAA morphology in individuals at risk of stroke could help doctors tailor treatment plans and identify those who might benefit from more aggressive prevention strategies. This may include anticoagulation therapy to prevent clot formation or the use of LAA closure devices to physically seal off the appendage and prevent clots from escaping. Further research is needed to refine these strategies and determine the optimal approach for different LAA morphologies.

Beyond LAA morphology, what other factors contribute to cryptogenic strokes, and how might future research address these?

While LAA morphology is a significant finding, other factors likely contribute to cryptogenic strokes. These may include undetected paroxysmal atrial fibrillation (episodes of AF that come and go), patent foramen ovale (PFO), hypercoagulable states, and subtle cardiac abnormalities not easily detected by standard imaging techniques. Future research should focus on developing more sensitive diagnostic tools to identify these hidden causes, as well as exploring the interplay between multiple risk factors. This could involve advanced cardiac imaging, prolonged cardiac monitoring, and genetic studies to identify individuals with a predisposition to cryptogenic strokes.