Cardiovascular disease (CVD) is the collective term used to describe any disorder of the heart and circulatory system; the most common cardiovascular diseases are coronary artery disease and stroke.
Coronary artery disease is caused by a build up of fatty deposits and cholesterol on the inner artery walls over time. This build up can eventually lead to stenosis or narrowing of the arteries. As the arteries narrow it decreases the hearts ability to pump blood and oxygen to the body’s vital organs. This process can occur to a greater extent in some people and can result in a blockage. If the blockage is not cleared within 12 hours, it will result in cell death (necrosis) in the effected area. When this process occurs in the heart it is called a heart attack or myocardial infarction (MI). Symptoms include chest pain, shortness of breath, palpitations and nausea. In patients with diabetes however it is not unusual for myocardial ischaemia to be silent that is to occur without any symptoms due to associated nerve damage. There are several risk factors for CVD including high blood pressure, elevated cholesterol, diabetes, smoking, obesity and family history.
There are 2 types of stroke Ischaemic stroke and haemorrhagic stroke. Ischaemic stroke is cased by a blockage in one of the arteries taking blood to the brain whereas haemorrhagic stroke is caused when a blood vessel bursts causing bleeding in the brain. Common symptoms include slurred speech, paralysis of one side of the body, blurred vision or loss of sight.
The World Health Organisation estimated that 17.1 million people died from CVD in 2004, this figure represents approx 29% of all deaths making CVD the number one cause of death globally.
Myocardial infarction is generally diagnosed using a combination of clinical symptoms, characteristic changes on the ECG and a rise and fall in biochemical markers (cardiac enzymes).
Cardiac enzymes are the term given to the proteins released into the blood by dying heart muscle. They are typically elevated in the blood several hours after the onset of MI and therefore can be used as markers to confirm the diagnosis of heart attack.
The most commonly used diagnostic markers for cardiovascular disease are CK-MB, Myoglobin and Troponin.
The fact Myoglobin is not specific to the heart and more specific markers like Troponin I and CK-MB do not peak until much later has led to extensive research into additional markers to improve diagnosis. The following novel markers have proven to be highly specific early indicators of MI.
Early diagnosis of acute myocardial infarction (AMI) is essential in providing patients with the appropriate treatment and preventing inadvertent discharge. Early detection will also help reduce the number of patients unnecessarily admitted to hospital and treated for AMI. Not only will healthy individuals not benefit from treatment, the unnecessary treatment could result in considerable harm. The ability to detect or disregard AMI early will dramatically decrease costs and the risk of associated litigation.
In the majority of cases it is recommended blood is obtained and tested 6 to 9 hours after the onset of symptoms. If results are negative and suspicion remains high blood should be sampled again at 12 to 24 hours. After AMI has been confirmed biochemical marker testing at a reduced frequency is valuable in determining the size of the infarction and the risk of re infarction.
Randox offer two different cardiac arrays capable of simultaneously testing a single patient sample for multiple cardiac markers.