Atypical ECG Findings in Rare Cardiac Conditions

Introduction:

To ensure proper diagnosis and equitable heart health for everyone, awareness should be promoted for rare heart disorders. With approximately 6,000 rare diseases, some of which damage the heart. Many are genetic and manifest early; nevertheless, a lack of awareness results in a delayed diagnosis, which presents patients and families with significant difficulties. However, these disorders can be identified and sorted out soon with the help of a diagnostic tool like an Electrocardiogram (ECG).

What Are the ECG Findings in Long QT Syndrome?

Long QT syndrome (LQTS) is a heart rhythm problem that often occurs during childhood. It's identified by a longer-than-normal QT interval on an ECG (a heart test) and is usually accompanied by fainting or sudden cardiac arrest. These symptoms often happen when a person with LQTS is stressed or suddenly startled by a loud noise.

Electrocardiogram of Long QT Syndrome:

• In an ECG for long QT syndrome (LQTS), doctors look for patterns like a longer QT interval, abnormal heartbeats, and specific T-wave shapes.

• These patterns vary with the type of LQTS. While ECG can help diagnose LQTS, it's not foolproof, and some LQTS cases don't show these patterns.

• To check for prolonged QT intervals, doctors use age and sex-specific criteria.

• If the QT interval is longer than a certain value, it suggests LQTS, but about 10 % to 15 % of gene-positive LQTS cases have a normal QT interval.

• In borderline cases, doctors may monitor the heart rate during exercise or over time to see if the QT interval acts abnormally.

• Invasive tests aren't usually needed for LQTS diagnosis; ECG and non-invasive methods are usually enough.

What Are the ECG Findings in Chagas Disease?

Chagas disease is mainly found in 21 countries in Latin America. People primarily get it from "kissing bugs," which live in poorly built homes of mud, straw, or palm thatch. These bugs come out at night, bite people, and leave their poop near the bite. The poop contains a parasite that can enter a person's body if they accidentally touch the poop and then touch the bite, eyes, or mouth. The parasite can also spread from a mother to her child during pregnancy or birth through contaminated food or drinks, blood transfusions, organ transplants, or even laboratory accidents. So, it's important to know how the disease can spread.

Electrocardiogram of Chagas Disease:

• In Chagas disease, specific ECG patterns can indicate the risk of heart failure.

• A prolonged QRS duration (>100 milliseconds) suggests weaker heart function and a larger left ventricle. It doesn't pinpoint regional heart abnormalities or aneurysms.

• Longer QRS duration is linked to reduced heart function and ventricle enlargement.

• A QRS duration >120 milliseconds and QT interval >440 milliseconds may predict heart function decline.

• Common ECG issues include irregular heartbeats and conduction problems.

• The QRS score estimates the extent of heart damage, with a score of>2 indicating damage.

• These findings help monitor and manage Chagas disease-related heart problems.

What Are the ECG Findings in Transthyretin Amyloid Cardiomyopathy (ATTR-CM)?

Amyloidosis is a group of diseases where abnormal deposits of misfolded proteins called amyloid fibrils build up in various organs in the body. This buildup can make these organs stop working correctly, eventually leading to organ failure.

Electrocardiogram of ATTR-CM:

• The ECG of ATTR-CM often shows certain patterns like low voltage ECG and unusual Q waves unrelated to heart attacks.

• These patterns can help doctors tell ATTR-CM apart from other conditions that thicken the heart muscle.

• ECG results could be more reliable for ATTR-CM diagnosis. Only 25-40% of patients with ATTR-CM have these patterns, and it depends on how you define low voltage.

• Sometimes, a different ECG pattern can appear in a specific type of ATTR-CM.

• So, an ECG alone cannot confirm or rule out ATTR-CM, and it is not a good screening tool.

What Are the ECG Findings in Rheumatic Heart Disease?

Rheumatic heart disease is a serious heart condition that happens when the heart valves get damaged due to multiple bouts of rheumatic fever. Rheumatic fever is an inflammatory response caused by streptococcal bacteria. These bacteria can spread easily, especially among children. When someone has repeated strep infections, it can lead to rheumatic fever. During rheumatic fever, the immune system mistakenly attacks the body's tissues, including the heart valves. This causes inflammation and scarring in the heart, which, over time, can lead to rheumatic heart disease. It's a condition where the heart valves and muscles don't work properly because of this damage.

Electrocardiogram of Rheumatic Heart Disease:

• In acute rheumatic heart disease, an ECG often shows a faster heart rate (sinus tachycardia), but it can also be slower in some cases (sinus bradycardia, especially in children).

• First-degree atrioventricular (AV) block, a minor ECG abnormality, can sometimes be seen but isn't a clear sign of rheumatic heart disease.

• More severe AV blocks may occur but usually worsen as rheumatic fever resolves.

• If there's inflammation around the heart, the ECG may show elevated ST segments in specific leads.

• Rheumatic heart disease-related valve problems can lead to irregular heart rhythms like atrial flutter, multifocal atrial tachycardia, or atrial fibrillation.

• The ECG might also indicate an enlarged left atrium or left ventricle, depending on the valve affected.

What Are the ECG Findings in Restrictive Cardiomyopathy?

Restrictive cardiomyopathy (RCM) is a heart condition where the heart chambers become stiff over time. While the heart can squeeze blood out, it struggles to relax between beats, making it hard to fill with blood. This leads to fluid buildup in the body, especially the lungs, causing symptoms. It also raises pressure in the heart chambers and can enlarge the atria. RCM increases the risk of irregular heart rhythms and eventually weakens the heart's ability to pump blood effectively, often leading to heart failure. RCM is uncommon and can affect people of any age.

Electrocardiogram of Restrictive Cardiomyopathy:

• Low voltage QRS complexes denote the signals from the heart's electrical system are weaker than usual.

• Non-specific ST segment/T wave changes show irregularities in the heart's electrical signals but don't point to a specific problem.

• The bundle branch blocks mean the electrical pathways in the heart can get blocked or delayed, affecting how the heart beats.

• Atrioventricular block causes delay or blockage in the signals between the upper and lower chambers of the heart, leading to slower or irregular heartbeats. In severe cases, a complete blockage can happen.

• Based on the ECG results, pathological "pseudo-infarction" Q waves can make it seem like there was a heart attack when there wasn't one.

• Atrial and ventricular dysrhythmias mean the heart's rhythm can become irregular, with the upper and lower chambers not beating in sync.

Conclusion:

Findings from ECGs are essential for diagnosing and comprehending uncommon cardiac diseases. Despite not always being precise, these findings can offer essential insights into diagnosing and treating certain disorders. ECG is a crucial tool in the fight against uncommon heart disorders because early detection can result in improved outcomes.