Which is the most preferred biomarker used in diagnosing an early heart attack?

The symptoms of heart attack can be mild and they can get confused for common discomfort or less serious problems. The recognized signs of heart attack are chest pain, sweating, palpitation, and shortness of breath. However, not all heart problems come with clear warning signs. There is not always a sudden pain followed by a dramatic fall to the floor, like in the movies. Shoulder pain, discomfort in the neck and arm, burning sensation, vomiting, and fatigue are some of the less known symptoms of a heart attack.

Acute coronary syndrome consists of a spectrum of diseases such as unstable angina, stable angina to myocardial infarction. Is there any test to diagnose acute coronary syndrome when having unidentified symptoms?

Tests like electrocardiograms and echocardiograms can help in monitoring heart health. A genetic test to understand predisposition like cardiomap is good to understand the underlying risks. A simple blood test called a cardiac biomarker can give an easy diagnosis of the heart condition. Let's delve into more details of cardiac biomarkers. 

When are Biomarkers Most Helpful?

Cardiac biomarkers, earlier known as cardiac enzymes, are simple blood tests. When there is damage to the heart muscle, cardiac biomarkers enter the bloodstream. Analysis of cardiac biomarkers helps in making a rapid diagnosis of heart attack so that appropriate clinical decisions are made.

Types of Cardiac Biomarkers 

Some of the current cardiac biomarkers are routinely used by physicians to evaluate, diagnose, and treat acute coronary syndrome.

1. Cardiac troponins: Current guidelines from American College of Cardiology (ACC) and European Society of Cardiology (ESC) recommend Troponins to diagnose myocardial infarction (MI). Troponin exists in two forms: Troponin I and Troponin T. Troponin I is highly specific to the heart and stays longer than other forms of cardiac biomarkers.
2. CK-MB: When a heart attack occurs, the injured heart muscle releases CK-MB into the blood. A sensitive marker appears in the bloodstream after 4–6 hours after heart attack and it peaks 10–12 hours for early diagnosis. Earlier the diagnosis of heart attack, better the outcome of medical or surgical intervention.
3. Myoglobin: A small heme protein rises early within one hour compared with cardiac Troponins and CK-MB. Though myoglobin is released when any muscle is damaged, its kinetics, i.e., early release still makes it one of the markers.
4. LDH: This enzyme is not used as commonly as Troponin. LDH1 is found in the heart and LDH2 in the bloodstream. A high ratio of LDH 1 to LDH2 suggests MI. The levels of LDH1 and LDH 2 return to normal after 10–14 days.
5. Alanine Transaminase levels (SGOT): It was the first marker used for MI.  Now, it is not specific for heart damage.

How can Mapmygenome help?

• All above tests are available at our centre.
• For first degree relatives, CardioMap is suggested to assess the risk of acute coronary heart disease.
• Our genetic counselors analyze your health history. They look at your family history to assess your predisposition, occurrences, and recurrences of acute coronary syndrome. Their expertise will help you choose the right genetic test and other necessary interventions to prevent acute coronary syndrome.

References:

1.“Learn the Heart | LearntheHeart.com.” Healio.com, 2018, www.healio.com/cardiology/learn-the-heart.

2. Mayo Clinic. “Heart Disease - Diagnosis and Treatment - Mayo Clinic.” Mayoclinic.org, 2018, ww.mayoclinic.org/diseases-conditions/heart-disease/diagnosis-treatment/drc-20353124.

Cardiac markers are substances that are released into the blood when the heart is stressed or damaged. These are often referred to as biomarkers and are helpful in evaluating heart function. The measurements of these biomarkers are vital in the diagnosis of cardiac ischemia and acute coronary syndrome (ACS), these are conditions that are associated with insufficient blood flow to the heart.

Conditions when the heart is under severe stress causes cardiac markers to show up in the blood, for example after a heart attack. In these situations the levels of biomarkers present can be quickly used to find out how seriously the heart was affected and the size of the heart attack.

The cardiac markers listed below are often routinely used in diagnosing a heart attack.

• Cardiac Troponin (TnT  and cTn-I): Are the most common biomarkers used, offering the highest sensitivity and are now widely accepted as the best markers for finding a heart attack. Can enter into the bloodstream straight after a heart attack and can stay in the bloodstream for many days, even after all the other biomarkers have returned back to normal levels. Cardiac troponins are specific for heart muscle and several studies have even found a direct correlation between cardiac troponin levels and long term outcome following a chest discomfort episode. This suggest that it is an instrumental tool in helping to identify individual’s that may be either high or low risk for future heart problems. For troponin T, the expected normal reference value is less than 0.1ng/mL and for troponin I, then it is less than 1.5 ng/mL.
• Creatinine Kinase (CK): The levels of this enzyme can usually double after a heart attack. However, it is not very specific since many other conditions are also known to elevate the levels of CK besides a heart attack. The main function of creatinine kinase is to transfer a phosphate group from ATP to creatine. It is essentially made up of B and/or M subunits (CK-BB, CK-MM and CK-MB isoenzymes). The normal reference value is between 30-180 units/L for males and 90-150 for females.
• Creatinine Kinase-MB (CK-MB): A subtype of CK and is more sensitive for measuring heart damage following a heart attack. Levels of CK-MB are found to rise 3-12 hours after a heart attack and generally return to normal levels are 1-2 days. CK-MB is regarded as the benchmark for cardiac markers of myocardial injury and it is also used to demonstrate if thrombolytic therapy has been successful. This is confirmed by the unmodified MB form being rapidly flushed into the blood and become the dominant form. The normal reference value ranges between 10-20 units/L.
• Myoglobin: A small protein that functions in the storing of oxygen, this is not specific in finding a heart attack but is often used alongside troponin to help diagnose a heart attack. Myoglobin can be found both in myocardial and skeletal muscle, it is rapidly released following tissue injury or trauma. The levels can be elevated within an hour of the injury. The normal reference values are below 110 ng/mL.

Other proteins which are also useful cardiac markers include C-reactive protein (CRP), ferritin, haptoglobin, cystatin, fibrinogen, homocysteine and natriuretic peptides especially B-type natriuretic peptide (BNP). It is important that cardiac biomarkers are measured in all patients who experience chest discomfort consistent with acute coronary syndrome (ACS). Any presence of elevated levels cardiac enzymes should be interpreted in the context of ECG and alongside clinical findings.

USE OF CARDIAC MARKERS

There have been medical clinical trials that have demonstrated the benefits of using cardiac markers as indicators for some specific therapeutic interventions in acute coronary syndrome.

Cardiac markers are essential for the timely and accurate diagnosis and management of various diseases and illnesses. There are no complications associated with cardiac marker tests. There is an increasing level of interest in the use of cardiac markers to manage and guide the health of oncology patients who are receiving cancer therapies.

As mentioned, cardiac markers are useful for diagnosing and managing patients with suspected acute coronary syndrome and chest pain. They are also used for the prognosis and management of patients with heart failure, and pulmonary embolism amongst other diseases. Cardiac markers can be divided into those that signify myocardial necrosis and those indicating myocardial ischemia.

Ischemic heart disease is one of the leading causes of death and one of the most common reasons for patients attending Accident and Emergency departments in hospitals. Many people will have symptoms and chest pain for some time before seeking help. The best use of cardiac markers depends on what they are being used for by the practitioner. Cardiac markers that have high positive predictive values are best to treat and manage those patients who have a high risk of cardiovascular complications. Cardiac biomarkers essentially are measurements that are taken with the aim of improving diagnosis and management of disease. Cardiac markers have seen great development in recent years especially when it comes to managing human health. Markers have provided increased sensitivity when it comes to diagnosing myocardial cell injury and heart failure. The diagnosis and management of disease early enables early detection and better chances of improved life and health for many patients.

Using biomarkers has become the norm for many areas of medicine, and they are used in a more widespread manner in cardiology. The use of cardiac biomarkers was first recorded in 1954. Since then they have been used extensively by clinicians. Since 1954 there have been huge leaps made in the research and use of biomarkers and the development of laboratory biomarkers and procedure. The future of biomarkers will continue to develop and become even more sophisticated for greater prognostic accuracy precision and greater diagnostic ability. This will enable clinicians and health care practitioners facilitate targeted therapy for patients and measure treatment responses. However, it is fair to say that biomarkers are the most useful when they are related to and applied to a very specific clinical query or question.

Cardiac enzymes, or biomarkers, include troponin, myoglobin and creatine kinase.

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