Last partial update: July 2019
Heart attacks and angina - Vascular disease in the arteries supplying the heart muscle
Coronary Artery Disease is vascular disease in the arteries that supply the heart muscle. These are called the coronary arteries. Even though the heart is full of blood, a system of small arteries is still required to supply the heart muscle with the blood it needs to function.
If the blockage associated with a vascular lesion in a coronary artery is severe enough, the oxygen the artery supplies to some heart muscle will be insufficient for that muscle tissue to function normally. It is this lack of oxygen that causes the chest pain associated with this disease, commonly termed angina pain.
Episodes of angina initially start to occur when the heart muscle needs more oxygen than normal, such as during exercise. In this situation, the blocked vessel can supply adequate oxygen to the heart muscle while the person is resting, but inadequate oxygen to allow the heart to work harder during exercise. The angina episode and the associated pain are only temporary (less than 20 minutes) and there is no permanent damage done to the heart muscle.
Myocardial Infarct or Heart Attack
Sometimes a sudden large increase in the degree of artery blockage can occur. (See section 'Vascular disease - An introduction.) When this happens, the reduction in blood flow causes the heart muscle to suffer a prolonged period of inadequate oxygen supply and results in death of heart muscle cells; and not uncommonly the person! The death of heart muscle is called a myocardial infarct or heart attack. This dead tissue cannot be replaced.
The actual death of heart muscle cells starts after about one hour and, after several hours, irreversible damage is being done to the heart muscle. This is why any anti-clotting therapies, such as taking aspirin, or procedures to open up a suddenly blocked artery, such as stenting, must be done very soon after the blockage occurs. To take advantage of surgical treatments such as stenting, the affected person must go to a hospital as soon as possible after chest pain symptoms start.
What is heart (angina-like) chest pain like?
All chest pain needs to be taken seriously and any pain that might be angina needs to be assessed in hospital.
Typically angina pain is felt centrally in the chest. However, it can also be felt in the neck, jaw, left arm, back or in the upper abdomen where it can be confused with dyspepsia like symptoms. The pain is usually described as a crushing or vice-like pain. However, it can mimic other types of pain, especially stomach pains. It is usually not related to breathing. The pain is also usually (but not always) significant and stops any activity the person is doing at the time. It usually comes on gradually and lasts for a few minutes at least. During this time it is fairly constant and does not tend to come and go. It will often come on with exercise although this is not always the case, especially when it is associated with a heart attack rather than a short angina episode .
It needs to be emphasised that for some people angina pain can be very unusual and therefore difficult to diagnose. Thus, help should be sought even if the pain being suffered is not ‘typical’ angina pain. Occasionally there is no pain at all and the person presents with shortness of breath or nausea and vomiting. Unusual fatigue or weakness is also a common symptom with ischaemic heart disease, especially in women. When worried by such symptoms or unusual chest pain, a person needs to seek help to sort out the cause. It is not safe to assume that the problem is not serious just because the pain is not typical, angina-like pain.
It is worthwhile also pointing out that some people, especially elderly females, can have heart attacks with no symptoms at all. They are just picked up the next time the person has an ECG (cardiograph).
What should a person do if he or she has heart (angina-like) chest pain?
The first thing to do is not to minimise the significance of the symptoms. All angina-like chest pain (see above) needs to be taken seriously, especially if it has any of the following features as they suggest that a heart attack may be occurring;
- Pain that lasts longer than 10 minutes.
- Pain that is not relieved by under-the-tongue medication angina medication. (Only people with a past history of angina are likely to have such medication.)
- Recurrent short episodes chest pain / discomfort
- Pain associated with fainting or loss of consciousness or shortness of breath
Such symptoms indicate a medical emergency is occurring and the patient requires transport to hospital by ambulance as soon as possible.
Why is getting to hospital quickly very important?
There are two reasons why people with chest pain need to get to hospital quickly:
- When having a heart attack, the person’s heart may start to beat in an abnormal manner. This is termed an arrhythmia and some of these arrhythmias can be fatal. In fact, most deaths that occur in the early stages of heart attacks are due to arrhythmias and such deaths are unfortunately not uncommon. The good news is that treatment with a defibrillator can often quickly reverse these potentially fatal arrhythmias and thus save many lives. Defibrillators are present in all casualty departments and in all ambulances in Australia.
- The sooner the person reaches hospital, the sooner he or she can be treated and in many heart attack cases early treatment can result in significantly less permanent damage to the heart.
Unfortunately, despite extensive public awareness campaigns, many people (especially men) are not seeking help quickly enough, with only about 40 per cent of patients seeking help within an hour of chest pain symptom onset. This means slower treatment and slower treatment means more deaths and larger heart attacks. It is important to ring the ambulance as quickly as possible.
Do not wait to see if symptoms go away; and do not feel embarrassed about calling, no matter what the time. No one will criticize a person for being careful and ambulance drivers are sitting waiting for calls from people with chest pain 24 hours a day, seven days a week.
Getting to hospital
By far the best way to get to hospital is by ambulance and the first thing people should do if they suspect they are having a heart attack is to ring the ambulance straight away. They will usually arrive and be able to start treatment within as little as five to ten minutes. This is far less time than it takes to get organized to go to hospital let alone actually get there. And once the ambulance arrives, there is a life-saving defibrillator at hand should it be needed, as well as other helpful drugs and oxygen which the ambulance person is well practiced at administering. (He or she will have treated many more early heart attack cases than most GPs.)
In some remote areas an ambulance may not be available. If this is the case the person should make sure someone else drives them to hospital to avoid putting himself or herself and other drivers at risk. It is also advisable to get someone to ring the hospital to let staff know a patient with chest pain is coming.
While it is reasonable to speak with a local doctor on the phone regarding an episode of chest pain, this should be done after the ambulance has been rung. Do not go to a doctor’s surgery as this will only delay treatment in hospital and this delay may prove fatal.
Take an aspirin:
Unless you are allergic to aspirin, a person suffering from chest pain should take an aspirin as soon as possible as it will help dissolve the clot that is causing the heart attack.
Surgical treatments for coronary artery disease
Coronary artery disease can be treated by bypassing the blockages in the arteries. This procedure is called coronary artery bypass grafting and is done using a vessel from another part of the body, often leg veins. About 16,000 were done in Australia in 2001-2. Angioplasty uses an inflatable balloon to expand the blocked coronary artery. The artery is then usually held open by placing an expanding metal tube, called a stent, at the blockage site. Newer stents are impregnated with chemicals that reduce the risk of them becoming blocked in the future by clots. About 24,000 angioplasties and 22,000 stent insertion procedures were done in Australia in 2001-2.
Medical tests and the investigation of coronary artery disease
Testing for coronary artery disease needs to be discussed in terms of whether the person has symptoms of the disease or not.
a. People with heart disease symptoms: Tests to determine the presence of coronary artery disease are essential in people that have symptoms suspicious of coronary artery disease and they are very useful in determining the extent of the disease. Any one who has had episodes of chest pain suggestive of angina heart pain should see a doctor immediately. Other symptoms that may suggest heart disease symptoms include shortness of breath, palpatations and unusual fatigue, especially if they occur when exercising.
b. People who have not had heart disease symptoms: Medical tests are much less accurate and can be difficult to interpret in people without symptoms of heart disease, with numerous false positive and false negative tests occurring (see below). Tests that patients without symptoms of coronary artery disease might encounter will be discussed briefly here because they are commonly done and are currently the topic of considerable public debate. Investigations done on patients with heart symptoms or established disease such as coronary angiography are beyond the scope of this preventatively oriented publication.
ECGs (cardiographs):
As a general principal, ECGs tell what has happened to a person’s heart rather than what will happen. Thus, with respect to coronary artery disease, they can really only show damage that has already occurred to the heart. While this is still very useful information, it unfortunately misses many individuals who are at risk of having a heart attack. A normal ECG just means any existing artery blockages have not caused any damage to the heart yet. It should be stressed that ECGs provide much useful information in addition to that related coronary artery disease and they are relevant and necessary in many clinical situations.
Exercise ECGs (stress tests):
As well as showing heart muscle that has died, ECGs can become abnormal in appearance when the oxygen supply to the heart muscle is only just adequate. An exercise ECG is a cardiograph done while a person is exercising. It will pick up more people with coronary artery disease because, during exercise, the heart muscle requires more oxygen, and thus blood supply, than it does at rest. A normal resting ECG may become abnormal in appearance during exercise because an artery supplying adequate blood/oxygen at rest may be too diseased to be able to supply the exercising heart’s increased blood/oxygen demand.
This test is useful in helping diagnose patients who already have symptoms such as chest pain. Unfortunately it is often inaccurate in those who do not, giving either false positive and false negative results in about 30% of cases. A false positive test can result in additional unnecessary and potentially hazardous testing, such as coronary angiography, whilst a false negative test misses the individual who has a 'small' artery blockage that still might suddenly rupture, causing a heart attack. This is a common occurrence as the majority of heart attacks occur in arteries that are less than 40% to 50% blocked. A stress test usually only picks up diseased arteries with lumens that are over 50% blocked.
In about half the patients with coronary artery disease, the first symptoms occur in association with a heart attack occuring and for many of these individuals, an ECG (and probably a stress test) prior to the heart attack would not have been much help in predicting this event.
Detection of calcium in arteries by electron beam computed tomography (a high resolution CT scan):
Many vascular lesions in coronary arteries contain calcium and high resolution CT scans have been used to measure the amount of calcium in the walls of coronary arteries. The assumption underlying the test is that the amount of calcium present reflects the degree of vascular disease and that the level of the 'calcium reading' will be able to help in predicting the likeihood a heart attack will occur. (The amount of calcium is expressed in terms of a score called the Agatston score). Unfortunately the usefulness of this investigation is limited for several reasons.- It does not give an idea of whether the lesion present is a lower-risk stable lesion or a higher-risk unstable lesion; nor does it indicate how much obstruction the lesion is causing.
- The calcium level does not consistently reflect lesion severity and thus it can miss or underestimate the significance of lesions that contain relatively low levels of calcium.
- It is an expensive test and it is not covered by medicare so the person has to pay all the cost involved.
- With regard to helping predict heart attack risk or deciding on further investigation / treatment, there is no evidence from prospective studies that calcium scoring improves existing patient outcomes; that is, there is no evidence it increases the benefits already provided by overall risk factor assessment. This means that:
- in people who have no symptoms of heart disease, there is no good evidence that an abnormal calcium score result should change existing patient management.
- doctors do not know whether the test is adds additional helpful information with regard to deciding on further management and thus it is hard to justify the additional substantial cost.
At present its role is limited to helping further assess people whose risk factors indicate that they are at intermediate risk.
Ankle brachial Pressure Index
This test basically provides an indication of the pressure difference in major arteries between the upper and lower limb and can be used as an indicator of vascular disease in the lower limbs. A ratio of less than 0.9 indicating significant disease is present and that risk factors for vascular disease should be addressed. A level greater than 1.4 is also of concern as it may indicate calcified, non-compressable arteries. This test is not a substitute for risk factor assessment.
Coronary Angiography:
Coronary angiography is a specific test to determine the extent of coronary artery disease in individuals with symptoms suggestive of this disease. It is not a screening test for individuals without symptoms.
Heart Failure – The forgotten heart problem Heart failure is a common and debilitating problem in many older Australians and this situation is made worse by the fact that it is often either undiagnosed or under-treated in many patients. Heart failure is a condition where the heart muscle can not pump an adequate supply of blood to the body. While there are numerous causes, about 75% are attributable to just two factors; the death of some of the heart muscle following a heart attack and damage to heart muscle caused by long-standing high blood pressure. Diabetes is also an important causal factor. It is an increasingly common condition in Australia for two reasons. Firstly, it is a condition that increases with age and Australia's population is ageing. Secondly, with improved treatments fewer people are dying following heart attacks, leaving more people alive with damaged heart muscle. Depending on how the condition is defined, between 3% and 5% of the adult population over 65 years of age have symptomatic heart failure; and this figure climbs to 10% in those over 75 years of age. In all, about 300,000 Australians are affected with 30,000 new cases being diagnosed each year. About two thirds are female. Disturbingly, a similar proportion of the older population has 'silent' heart failure; that is, abnormal heart functioning that is not yet severe enough to cause symptoms or causes symptoms that the patient does not recognise as being abnormal. Part of the reason for this is that common early symptoms of heart failure, such as tiredness and mild shortness of breath, are viewed by many older people as just being a normal part of ageing and therefore these symptoms tend not to be reported to doctors. Thus, many early cases are missed and a high index of suspicion needs to be held for the condition in the elderly and in people who have had a heart attack or who have high blood pressure. There are numerous effective treatments, especially when the condition is recognised early. Medications commonly used include angiotensin converting enzyme (ACE) inhibitors (or angitensin II receptor antagonists when ACE inhibitors cause significant side effects), beta blockers and diuretics. (Other medications used include digoxin, nitrates, hydralazine, aldosterone antagonists such as spironolactone and eplerenone, and amiodarone.) As a general rule, doctors aim to maintain systolic blood presure (the upper reading) at 105 to 110mmHg and heart rate at 55 to 60 beats per minute in people with heart failure. (There will be exceptions to this general rule.) Other treatments include regular physical activity (as appropriate), treatment of co-existent sleep aponea (see sleep apnoea section), fluid restriction (1.0 to 1.5L/day), dietary sodium restriction (2 to 3g/day) (see section on preventing hypertension), smoking cessation, daily weight measurement (to help monitor body fluid balance), vaccination against influenza and pneumococcal disease and identification / treatment of depression. Alcohol should be ceased in people with alcohol cardiomyopathy; a disease of heart muscle caused by alcohol. Bed rest is only recommended during acute severe episodes of heat failure. Regular visits by a community nurse are helpful in education regarding fluid and salt restriction and monitoring body fluid balance and ensuring compliance with medications. Prevention rests on minimising the person’s risk factors for ischaemic heart disease, especially high blood pressure. These are discussed in the section 'Assessing your heart attack risk'. There is also some evidence that obesity can cause heart muscle damage and contribute to heart failure risk. (Obesity also increases the risk of heart attack risk factors such as diabetes and high blood pressure.) Some commonly used medications that should be avoided in people with heart failure include: medications for arthritis, steroids, tricyclic antidepressants, macrolide antibiotics, cisapride, calcium channel blockers, thiazolidinedione (giltazones) in people with diabetes, and medications for treating erectile dysfunction in men. |
Stroke (Cerebrovascular disease)
The death of brain tissue due to a problem with its blood supply is termed a stroke. There are two quite different mechanisms by which strokes occur.
Haemorrhagic strokes:
The least common (20% ) is caused by a haemorrhage (bleeding) into the brain tissue from a break in the wall of a small artery. These breaks usually occur at weak points in the artery called aneurysms. As most of these weak spots are present from birth, they are difficult to avoid. However, they are much more likely to rupture when a person has high blood pressure and avoiding this risk factor is the best way to minimize risk from this type of stroke.
Ischaemic strokes:
The more common type of stroke (80%) is called ischaemic stroke, which occur as a result of blockages in the arteries supplying the brain i.e. vascular disease. As with heart attacks, these arterial blockages deprive the brain tissue of blood and thus oxygen. Brain tissue is much more sensitive to lack of oxygen than heart muscle and brain tissue death commences after only three to four minutes of oxygen deprivation.
Blockages causing ischaemic strokes can be due to either of the following; an obstruction at the vessel wall lesion itself, similar to the process that causes heart attacks; or a piece of clot that forms over the vessel lesion breaking off and causing a blockage further down the vessel. This piece of clot is called an embolus and it usually arises from lesions in the major arteries of the neck, the carotid arteries. Once the embolus breaks off, it travels down the progressively narrowing artery until it is the same diameter as the artery lumen it is travelling through and cannot pass further. The artery becomes blocked at this point.
Sometimes, if the embolus is brittle, it can break up into smaller pieces and the artery can become unblocked. This is more common with small emboli and the symptoms of the stroke in this case are usually only short lived, lasting for a few minutes to hours. Such episodes are called transient ischaemic attacks (TIA) and they are much less common than strokes. Any episode that lasts longer than 24 hours is by definition a stroke, not a TIA. (TIAs also do not cause any changes on brain imaging investigations, such as CT scans and MRI scans.)
Symptoms caused by transient ischaemic attacks (and strokes) include weakness or numbness in an arm and / or leg, blurred or double vision, speech disturbances, dizzy turns or unsteadiness in walking. Limb symptoms usually affect only one side on the body. People who experience an episode like this should seek help at their nearest hospital urgently as it is a warning that they are at high risk of having a significant stroke and require urgent assessment and treatment. The risk of having a severe stroke after a TIA or minor stroke is about 10% (perhaps up to 20%) in the next seven days.
Unfortunately, in about 75% of cases, the first sign of cerebrovascular disease is a stroke rather than a TIA.
Very occasionally, emboli causing strokes or TIAs can come from clots that have formed in the left atrium part of the heart. This mainly occurs when a person has a special type of abnormal heart rhythm called atrial fibrillation. People with atrial fibrillation have a stroke risk of up to 10% per year (or even higher). Emboli can also more rarely happen if the heart valves become infected.
Stroke prevention
In Australia in 2019 there will be about 50,000 cases of strokes and TIAs and about 500,000 people living with disability from strokes. About 20% of people will be dead within a month of having the stroke. It is the third most common cause of death in Australia (5.2% of deaths in 2016) and accounts for about 3% of all disease burden. About 25% of strokes occur BEFORE the age of 65 and about half before 75. However the good news is that, as with heart attacks, the death rate from stroke has deacreased dramatically (74%) over the last 40 years.
As the majority of strokes are caused by vascular disease, prevention relies on looking after vascular disease risk factors throughout life; not just when getting older. Hypertension is especially important as it is implicated in causing both types of strokes.
Atrial fibriallation, an abnormal heaet rhythm, is also a very important risk factor for stroke. It occurs with increasing frequecy as people get older. About 10 to 15% of people over the age of 65 have this condition and don't know it. (In those over 80 years of age, the rate is 20%.) In total, about 300,000 people in Australia have this condition. This is a very serious problem as atrial fibrillation is thought to cause about 20% to 30% of all strokes. While the condition is often difficult to treat, putting people with the condition on anticoagulants greatly reduces the risk of stroke in people with the condition. All people over the age of 65 should be checked for the condition at their annual check up. It should be mentioned that high blood pressure and obesity are risk factors for developing atrial fibrillation and the condition can be prevented to some extent by avoiding these risk factors.
As about 75% of strokes without a prior TIA occurring, improved prevention relies on identifying high risk individuals and reducing their risk. The major risk factors for stroke are shown in the table below. People who do suffer a TIA have about a 6% chance of having a stroke in the following week.
Risk factors for strokes |
||
Risk factor group |
Ischaemic stroke risk factors (80% of all strokes) |
Haemorrhaigic stroke risk factors (20% of all strokes) |
Demographic |
Increasing age |
Subarachnoid haemorrhages are more common in women |
Family history |
First degree relative (with respect to subarachnoid haemorrhages) |
|
Modifiable |
High blood pressure |
High blood pressure |
Smoking |
Smoking |
|
Diabetes |
Excessive alcohol intake |
|
Increased cholesterol |
|
|
Attrial fibrillation |
|
|
Heart valve disease |
|
|
Existing disease |
Previous history of stroke or TIA |
Congeniral vascular malfornmations in the brain |
Previous heart attack or angina |
Brain tumors |
|
Peripheral arterial disease (usually affecting the legs) |
Decrease in ability to form clots due to disease |
|
Renal artery disease |
Decrease in ability to form clots due to medication e.g. antiplatelet therapy used to prevent ischaemic strokes and heart attacks |
|
Aortic aneurysm |
|
|
Treating modifiable risk factors:
1. High blood pressure:
Lowering blood pressure reduces stroke risk by about 30 per cent. (This reduction reqires a lowering of systolic BP (the higher reading) by 10mmHg or diastolic BP (the lower reading) by 5mmHg.)
2. High cholesterol:
Lowering cholesterol by 20 per cent (usually with a statin medication) reduces serious vascular events including stroke by 25 per cent and ischaemic stroke by 17 per cent. (It has no effect on haemorrhagic stroke.)
3. Atrial fibrillation:
As mentioned above, atrial fibrillation is an abnormality in the heart rhythm and it can lead to clots forming inside the heart. These can travel to the brain and cause the blockage of an artery and thus an ischaemic strokes. Such events are the cause of about 30% of all ischaemic strokes. This abnormal rhythm can be permanent or tend to come and go. Strokes are more likely to occur when the ryhythm tends to come and go.
The rhythm can sometimes be successfully treated by applying a mild electric shock to the heart or by medication, both of which can revert the heart rhythm back to normal. Such treatments do not always work and if the rhythm can not be returned to normal, then anticoagulant therapy is used to prevent clots forming within the heart. Warfarin is the most effective therapy and reduces strokes from such clots by about two thirds. Aspirin is less effective, reducing this type of stroke by about 20%. Warfarin does have the disadvantage of causing twice as many significant bleeds in other parts of the body (e.g. in the brain and gastrointestinal tract) as aspirin and it is thus often not suitable for use in people with a history of such bleeds. It is also less suitable for elderly patients as it can be a difficult medication to manage.
Antiplatelet therapy to reduce clotting and help (hopefully) prevent ischaemic strokes:
Antiplatelet therapy, most commonly using low dose aspirin, is only of overall benefit in people at high risk of cardiovascular disease. This is determined by the assessment of numerous risk factors for cardiovascular disease and is discussed in detail in the section 'Assessing your risk of heart attack'. High risk is defined as having a greater than 15% chance of having a major cardiovascular event in the next 5 years. In people at less risk, the side effects associated with long term use of aspirin, especially major gastrointestinal bleeding, brain haemorrhages and bleeding with surgery, are greater than any benefit obtained by taking this medication.
There have been many media reports stating the benefits of low-dose aspirin therapy and they have no doubt tempted many people to place themselves on long-term aspirin therapy without prior consultation with a medical practitioner. This should not be done as the vast majority of adults will be actually worse off on this medication.
Present research also suggests that the benefits of antiplatelet therapy are different for men and women.
- In men, antiplatelet therapy (most commonly aspirin) significantly decreases the overall risk of serious vascular events but this mostly occurs due to a reduction in heart attacks. There is no significant effect on the rate of ischaemic strokes and it causes a slight increase in haemorrhagic strokes.
- In women, antiplatelet therapy decreases the risk of ischaemic stroke by about 20% but does not decrease the risk of heart attack.
If stroke symptoms occur, seeking help early !!
Illness and death from strokes can be reduced by attending hospital as soon as possible after the onset of symptoms; within an hour is best but benefit can be gained from treatment up to 9 hours after symptom onset. TIME IS BRAIN.
To do this people need to be able to recognise the symptoms of a stroke and call an ambulance. People with symptoms should not wait to see if the symptoms go away. Rapid diagnosis and treatment can save considerable brain tissue, with resultant reductions in long-term disability of about 20%. (There is not much change in mortalit.)
What can be done once a stroke has occurred?: There are two main treatment options available to reduce the effects of a stroke once it has occurred. The first is giving medications to help disolve the clot that is blocking the artery. This treatment is available in almost every hospital in the country. The second is to physicaly remove the clot via a catheter inserted into the artery; It is grasped and then pulled out using the aid of suction. Currently (2017) this is only available in a few major hospitals in the capital cities. Both these proceedures can drastically reduce the disability caused by the stroke.
What is the time window to gain benefit from dissolving clots?: Until recently it was felt that treatment to dissolve / remove clots needed to be done within 4.5 hours of symptoms occurring to gain benefit. However, recent evidence suggests that the period is significantly longer; up to nine hours for using clot-dissolving drugs and even longer for clot-removing surgery.
This is good news as some people can't get to hospital within that time and others (about 20%) wake up with a stroke and thus don't know how long they have had the symptoms. At present only about 13% of people suffering a stroke get to hospital in the 4.5 hour window. To determine whether a person is likely to benefit after 4.5 hours, a special 'perfusion' CT Scan is done which can show whether there is brain tissue that is only partly affected and can be saved. This usually surrounds a central part that has died; like a halo. The larger the halo the better.
It should be noted that about 6% of people who have clot-dissolving medications suffer a bleed due to the medication and these patients do end up with a worse outcome. However, many more gain significant benefit from treatment. (Patients with larger lesions are more likely to have a bleed.)
Further information
National Heart Foundation
Their ‘Heart line’ information service Ph 1300 362 787