COMMIT-CCS2 logo ClOpidogrel and Metoprolol in Myocardial Infarction Trial
FACT SHEET 6
GLOSSARY
Ace inhibitors (angiotensin converting enzyme inhibitors) commonly used in treating chronic heart failure and high blood pressure, they are also used during and after a heart attack. They prevent the normal formation of angiotensin II, a hormone that causes constriction (narrowing) of the blood vessels. The drug allows blood vessels to dilate (widen), thus reducing blood pressure and making it easier for the heart to pump blood.
Acute Myocardial Infarction (MI) a heart attack (sometimes called a "coronary"). This is what happens when the supply of oxygen-rich blood flowing through one or more of the coronary arteries to the heart muscle is cut off. If the oxygen supply is severely reduced the heart can malfunction or cut out.
Angina a sensation of heaviness or tightness in the centre of the chest that may spread to the arms, neck, face etc. It is caused when the arteries narrow and reduce the amount of oxygen-containing blood reaching the heart muscle.
Anti-arrhythmic agents drugs used to treat abnormal heart rates and rhythms (arrhythmias). They stabilise the heartbeat and may be used long-term to prevent future heart attacks.
Anticoagulants drugs that help to reduce the risk of clotting (coagulation) of the blood. Clots are formed from small blood cells called platelets and from a protein called fibrin. Anticoagulants help to prevent fibrin from forming.
Anti-platelet agents drugs that help to prevent blood clotting by reducing the 'stickiness' of the platelets in the blood. The COMMIT/CCS-2 study drug clopidogrel is an anti-platelet agent.
Aspirin an antiplatelet drug - it works by inhibiting an enzyme complex called cyclooxygenase, blocking the formation of thromboxane A2, a potent agent that makes the platelets in the blood stick together. All patients in the COMMIT/CCS-2 study received aspirin.
Asystole total failure of the heart muscle to contract, leading to cardiac arrest.
AV block a condition in which the signals from the heart's upper chambers (atria) to the lower chambers (ventricles) are impaired or don't transmit. It is classified as first, second or third degree (complete) heart block.
Beta-blockers drugs that block the transmission of adrenaline and noradrenaline - hormones that make the heart beat faster and more vigorously. They are used to lower blood pressure, to help prevent angina, to help control abnormal heart rhythms and to reduce the risk of a further heart attack. They are also used in certain types of heart failure. The COMMIT/CCS-2 study drug metoprolol is a beta-blocker.
Bleeding in the COMMIT/CCS-2 study, non-cerebral bleeding is defined according to severity as "major" (i.e. required transfusion or caused death) or "minor" (any other overt bleeding, including skin bruising).
Bradycardia a slow heart rate, normally defined as heart rate less than 50 beats per minute.
Bundle branch block bundle branches are an important part of the heart's electrical system, the system that coordinates muscular contraction to assure that the heart works efficiently as a pump. A block occurs when the system becomes damaged or diseased and stops conducting electrical impulses. In the COMMIT/CCS-2, about 7% of patients presented with new left bundle branch block, which is a strong indicator of an acute heart attack and confers a high risk of early death.
Calcium antagonists (also called calcium channel blockers) may be prescribed to treat angina and also high blood pressure. The muscle cells in the heart need a regular supply of calcium to work normally. Calcium antagonists reduce the amount of calcium entering the muscle cells of the arteries, causing them to relax. This increases the blood supply to the heart and reduces the amount of work the heart has to do to pump blood around the body.
Cardiac arrest a sudden profound disturbance in the heart's rhythm that stops the heart beating or prevents it beating enough to keep the body alive.
Cardiac rupture rupture of heart muscle, almost always leading to death, which can occur as a consequence of myocardial infarction and may be exacerbated by rapid reperfusion following fibrinolytic therapy.
Cardiogenic shock a state in which systolic blood pressure is less than 90 mm Hg, or 30 mm Hg below baseline, for at least 30 minutes, along with evidence of poor tissue perfusion (movement of blood through the tissues) that persists after any non-myocardial factors have been corrected.
Diuretics drugs used to increase the output of urine and remove excess fluid from the body. They are commonly used to treat high blood pressure and chronic heart failure.
ECG an electrocardiogram measures and records the electrical activity of the heart. Elevation of the ST segment, or evidence of new left-sided bundle branch block, on the ECG tracing is indicative of acute myocardial infarction.
Fibrinolytic therapy fibrinolytic or thrombolytic drugs (sometimes called "clot busters") are used to dissolve blood clots rapidly. They are most commonly given as emergency intravenous treatment in heart attacks (or certain types of stroke).
Heart failure a condition caused by weakening of the heart muscle, which makes the heart pump less efficiently than normal.
Hypertension high blood pressure - normally defined as a systolic pressure (measurement when the heart contracts) averaging 140 mm Hg or greater, and/or diastolic (measurement between heart beats) averaging 90 mm Hg or greater.
Hypotension low blood pressure, normally defined as systolic blood pressure less than 100 mmHg
Killip class a classification of the severity of heart failure from I (normal) to IV (cardiogenic shock). People in Killip class IV were excluded from COMMIT/CCS-2 because beta-blockers (such as metoprolol) are contraindicated in patients with cardiogenic shock.
Nitrates used to prevent and treat angina caused by coronary artery disease.
PCI (Percutaneous Coronary Intervention or balloon angioplasty) is a treatment to improve the blood supply through a coronary artery. A catheter with a small inflatable balloon is inserted into a vein in the groin and passed up to the affected artery. The balloon is gently inflated to widen the artery by pressing back the fatty tissue responsible for narrowing it.
Reinfarction a second or subsequent heart attack (myocardial infarction)
STEMI (ST segment Elevation Myocardial Infarction) An ECG measures the electrical activity of the heart. If the ST segments of the electrical wave pattern are elevated this is a strong indication of a heart attack with damage to the heart muscle due to blocked coronary arteries. About 90% of the patients in the COMMIT/CCS-2 study had STEMI based on their presenting ECG. ST segment depression alone (7% of patients in the study) is suggestive of less complete coronary artery blockage, and other tests may be needed to determine the extent of any heart muscle damage.
Stroke there are two types of stroke - ischaemic (or occlusive) which involves a blockage in a cerebral (brain) artery, and haemorrhagic which involves bleeding into the brain from an artery.
Ventricular fibrillation A life-threatening disturbance in the heart rhythm, which causes the heart to fibrillate (quiver) in a disordered way.