A heart attack occurs when the blood supply to the heart muscle (myocardium) decreases or fails as a result of occlusion of one or more coronary arteries

Heart attack: what is it?

By Cristiano Antonino On Sep 27, 2022

A heart attack occurs when the blood supply to the heart muscle (myocardium) decreases or fails as a result of occlusion of one or more coronary arteries

Myocardial infarction is a disease that affects more than two hundred thousand Italians a year and leads to death in 1/3 of the cases.

If the infarct only affects a limited area of the heart muscle, the consequences are not serious

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If the injury to the heart muscle is very extensive, it can lead to death or disability (to varying degrees).

What are the causes of a heart attack?

Normal coronary arteries appear as clean tubes.

But there are risk factors that predispose to the formation of atherosclerotic lesions that alter the arteries.

There are many factors that contribute to an increased risk of myocardial infarction.

Let us see what they are:

A) Age

Coronary atherosclerosis, like that of the other vascular districts, is a degenerative type of disease, essentially due to the inevitable senescence of the vessels; hence it is commonly said, and not wrongly, that we have the age of our vessels; and in spite of every desperate search for external and aesthetic rejuvenation, no one can sell us the youth pill.

B) Family history of heart attacks

Cardiovascular diseases tend to cluster in particular family units, so one ends up inheriting the predisposition to get sick, and descendants of coronary artery disease sufferers should be watched with particular care.

C) Sex

As far as sex is concerned, women, especially of child-bearing age, are relatively protected from coronary atherosclerosis compared with men.

The indices then gradually tend to level off after the menopause.

Using an Ebct (electron beam tomography), 541 women with an average age of 48 years were examined.

Those in whom the examination had revealed initial calcifications (not visible with conventional radiographic examinations) of the aorta and coronary arteries went on to suffer a heart attack or other coronary disease in the 15 years following the examination.

A disturbing result is this predictive capacity of the examination, which, precisely for this reason, is a formidable weapon of prevention.

All women who changed their risky lifestyles (high-calorie diet and excess animal fats) and brought their bad cholesterol (LDL) values within safe limits and their good cholesterol (HDL) values up, lowered their risk of heart disease.

It should also be mentioned, however, that heart attacks in females tend to be more severe than in males.

D) High cholesterol levels

The fats under indictment are total cholesterol, its LDL fraction and triglycerides, the increased rate of which in the blood is a definite risk factor; the decreased rate of another cholesterol fraction, HDL, which has protective functions, is also a risk.

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Hypercholesterolaemia per se is not a disease, but only a risk factor, and cholesterol is not a poison, but rather a fundamental constituent of all cells in the body.

The trouble is that due to bad eating habits, its level is abnormally high, which can be harmful in the long run.

Desirable cholesterol levels are around 200 mg/ml and cholesterolaemia dosage is part of good preventive medicine practice, especially in at-risk age groups (between 40 and 70 years), even though it seems appropriate today to address the problem of its control from childhood.

It is in doubt, however, whether it is worthwhile to carry out repeated and frequent cholesterol determinations in subjects over 70 and often octogenarians, even though it has been proven that cholesterolaemia reduction is useful even in old age.

What needs to be avoided is the state of anxiety and worry with which some late-life and often far beyond-risk subjects ‘chase’ their cholesterol levels frantically.

Hypertension
Diabetes
Obesity

Rather than obesity, it is better to speak of excess weight. Excess weight is most frequently accompanied by increased blood pressure, blood sugar, blood fat, and reduced physical activity; it is also a heavy burden that unnecessarily strains the heart.

According to recent data in the western world, about 30 per cent of the population is overweight to varying degrees.

It should be pointed out, in this regard, that obesity occurs when the body weight exceeds the ideal weight by 15 per cent.

The determination of ideal weight is achieved by various formulas.

A fairly widespread criterion defines the ideal weight as the number of kilos equal to the number of centimetres over a metre in height (thus, for a man who is 1.80 m tall, the ideal weight would be 80 kilos), but this criterion is perhaps more suitable for the 20-year-old who is physically active; for a sedentary 60-year-old, it seems excessively generous, and a reduction of at least 10% would be advisable.

It has also certainly been shown that a 20% increase in weight over the ideal in middle-aged individuals doubles the incidence of coronary artery disease, and triples it if obesity is accompanied by hypercholesterolaemia or hypertension.

Obese heart patients live on average four years less than the regular-weight heart patient.

Being severely overweight then anticipates the onset of the disease by 7 years in those who are predisposed.

In the United States, it has also been calculated that if cancer were eradicated, life would be extended by less than two years, while if obesity were eliminated, it would be extended by 5 years.

Smoking
Stress

The importance of stress is generally overestimated by patients.

To a large extent this is due to the fact that it is a term that has become very popular and widespread, being called upon for very different situations.

Since it is utopian and unrealistic to attempt to modify the environment positively in a substantial way, it is clear that our efforts are directed at identifying and possibly modifying those personality traits that, when subjected to environmental influence, may constitute a risk factor for coronary events.

Numerous in-depth studies have identified a specific behavioural attitude, defined as type A personality, which constitutes a definite coronary risk factor.

The constituent elements of type A behaviour are represented by a constellation of character attitudes that together contribute to determining a specific personality type.

In summary, the hallmarks of type A behaviour are haste, impatience, excessive competitiveness and a certain degree of hostility towards the social, work and family environment.

Within the framework of a global rehabilitation strategy, in which psychological attitudes play a fundamental role, the gradual resumption of one’s activities, with a different outlook and a different mentality, favours total social reintegration, the closure of a difficult and dark period of life, culminating in a serious ‘accident’, and the beginning of the patient’s psycho-physical reconstruction, on a new basis.

On a practical level, it is advisable to adopt a series of defensive attitudes, which could be summarised in the following tips: eliminate overwork; tackle and solve one problem at a time; create a hobby if possible.

Sedentariness

The subject of sedentariness, understood as reduced physical activity, is closely connected with that of excess weight.

A reduction in caloric expenditure, if income is kept constant, results in fat accumulation and weight gain.

Careful statistical investigations carried out in a large number of patients have made it possible to verify that physical activity results in a significant decrease in cardiovascular risk, both in primary prevention, i.e. in avoiding a first heart attack, and, more importantly, in secondary prevention, i.e. in avoiding a second heart attack in those who have already suffered one.

The mechanisms by which physical activity induces beneficial effects are well known, and are both direct and indirect.

Directly, physical training, i.e. regular and constant physical activity, produces beneficial effects through a reduction in heart rate and blood pressure under stress, resulting in a reduction in oxygen consumption by the heart muscle, improved oxygen utilisation by the skeletal muscles an improvement in overall work capacity, a shift in nervous control of the heart to the advantage of the vagus, the braking and sparing system, to the detriment of the sympathetic, the accelerating and wasteful system, an increase in the threshold at which ischaemia and angina appear during exertion, and threatening arrhythmias.

Indirectly, physical activity has beneficial effects through an increase in protective HDL cholesterol, a reduction in platelet aggregability, a reduction in blood pressure, circulating hormones that stimulate the heart, blood sugar in diabetes and triglycerides, obesity, and smoking habits.

There is no doubt, therefore, that physical activity should be encouraged and increased and that, on the contrary, a sedentary lifestyle should be avoided, thus reversing the deep-rooted tendency that imposed periods of long and almost complete, and sometimes definitive inactivity on infarct patients.

In most cases, myocardial infarction is due to the formation of a blood clot (clot) that obstructs a coronary artery.

It is in this case a coronary thrombosis.

It is rarer that the temporary contraction (spasm) of a coronary artery can trigger a heart attack.

When does a heart attack occur?

A cardiac infarction is usually the dramatic consequence of an illness that began many years earlier without manifesting itself until then; the triggering causes, which at a given moment abruptly precipitate a situation that was in equilibrium until a moment before, are very variable and not always identifiable.

Sometimes the pain occurs during intense physical exertion by an untrained subject: the ‘bachelor-wife’ football match played perhaps after a year’s work at the table and perhaps in the hot sun and after copious libations, is responsible for many early widowhoods.

Sometimes it is in association with intense and prolonged psychological stress, such as conflicts or quarrels in the family or work environment; sometimes it is strong and sudden emotions with unpleasant content, such as aggression, robbery, involvement in traffic accidents and disasters like earthquakes, floods, fires, etc.

In reality, in the vast majority of cases, it is not possible to identify the triggering mechanism of the infarct event, and indeed it should be remembered that numerous studies of chronobiology have irrefutably demonstrated that the greatest number of infarctions occur in the very early hours of the morning when the patient is in complete rest.

Fatal heart attacks are also said to be seasonal between December and January.

What are the symptoms of a heart attack?

The word angina introduces the subjective element of ischaemic suffering of the heart muscle: the symptom pain.

Both ischaemia and infarction generally cause angina pain, and in general the pain of an infarction is more intense and especially more prolonged.

The first symptom of a heart attack is pain, manifested as a feeling of discomfort in the chest.

The feeling of oppression, compression, pain or weight in the centre of the chest may radiate to the shoulders, neck, arms or back.

Infarction is often revealed by a combination of the following symptoms: profuse cold sweating in the upper body, dizziness, shortness of breath and nausea.

The shortness of breath is due to the inability of the heart to pump effectively and results, in some patients, in an oppressive feeling in the chest like a tightening rope.

If you are able to recognise the symptoms of heart attack and angina, you may be able to save the life of yourself or others.

If, on the other hand, you fail to recognise the symptoms or attribute them to another ailment (indigestion…), the heart attack treatment will come too late.

Unfortunately, in a good percentage of cases, both ischaemia and infarction may not be accompanied by pain: these conditions are respectively called silent ischaemia and silent infarction.

The prognosis, course and risk of ischaemia and silent infarction do not differ substantially from the forms that are accompanied by pain; these are not ‘mild’ forms of the disease; on the contrary, the absence of an alarm bell such as pain may ultimately expose the patient to a greater risk.

What is the difference between heart attack and ischaemia?

Ischaemia is the state of suffering of the heart muscle that is insufficiently supplied with blood.

There is a fundamental difference between infarction and ischaemia.

An infarct is a total interruption of blood flow to the heart, the symptoms of which last more than 15 minutes, do not disappear with rest or medication (with nitroglycerine they are only alleviated) and part of the heart muscle begins to die.

It is, therefore, a stable and irreversible condition.

Ischaemia is transient and reversible; it consists of a temporary interruption in the flow of oxygenated blood to the heart; the symptoms last a few minutes and can be relieved with rest or medication.

What determines the transition point between ischaemia and infarction is the duration of the absence of flow; in fact, the heart muscle can tolerate the absence of blood supply for a limited time (less than 30 minutes), beyond which it begins to go into necrosis, to die.

In most cases, ischaemia occurs when, in the face of an increased demand for oxygen and nutrients, and thus an increased flow, brought about by more or less intense physical activity, this demand cannot be satisfied due to the narrowing (stenosis) produced within the coronary arteries by atherosclerotic disease.

This creates a transient discrepancy between the need for supply and the possibility of flow adjustment; this is the condition known as ‘exertional angina’.

What happens in the area of the heart where the cells are dead?

In some cases of infarction, the portion of the wall of the heart muscle that is no longer contractile, scarred and thinned, protrudes during contraction (in systole), giving rise to what is called a ventricular aneurysm.

This, however, is a fairly rare consequence of an infarction; generally speaking, however, the thinning of the infarcted area, even without giving rise to the aneurysm, ends up causing a more or less serious alteration of the ventricular geometry, which responds to precise and rigorous physical laws, and a deterioration of the mechanical function of the pump.

It is intuitive that the ‘mechanical’ consequences of the infarct will be all the more serious the more extensive the thinned and non-contractile area is; generally, it is considered that the infarct is more or less serious depending on the site (anterior, or posterior or inferior).

Traditionally, it is believed that the posterior or inferior infarct is less serious than the anterior one; this may well be true, but the most important thing in determining both the immediate and distant prognosis of the infarct is not so much its site as its extension.

It is better, therefore, in this respect to distinguish small, circumscribed infarcts from large infarcts.

Moreover, the mechanical damage caused by a second infarct, especially if it affects a different area from the previous one, is added to that caused by the first one.

More to know about cardiac infarction

When to consult the doctor?

Any symptom that signals the start of a heart attack requires immediate medical attention.

If the doctor cannot be reached, call an ambulance and immediately reach the emergency room of the nearest hospital.

What do they do in the emergency room?

Once it is clear that the boundary between ischaemia and infarction is only temporal, and that there are times, albeit narrow, and means by which the evolution of ischaemia into infarction can be halted, the importance of the time factor is well understood.

The emergency room specialists, after a confirmatory electrocardiogram, will immediately start blood tests to measure the enzymes released during the infarction from the heart muscle (troponin, GOT, GPT, LDH, CK, CKMB).

What is the therapy for myocardial infarction?

Until recently, therapy consisted mainly of pain relief and treatment of early complications.

Modern therapy for coronary artery disease is based on three cornerstones: medical treatment (new drugs, known as thrombolytics, can now rapidly dissolve the blood clots that cause most heart attacks), coronary artery bypass surgery, and balloon dilation of stenotic coronary arteries (coronary angioplasty).