Heart Attacks

Please note that this article is not comprehensive and neither is it formal medical advice. It is recommended that the page on angina be read first. This is because angina is a symptom of heart attacks.

A heart attack occurs when the blood supply to a part of the heart is reduced so much that the part dies. In approximately 50% of cases, the heart attack is sudden and there is no warning. In the remainder, patients have symptoms which get worse beforehand (see unstable angina and ALARM study).

An important question is how can people tell that they are having a heart attack?

About 50% of heart attacks occur in people who have already been diagnosed with angina. For them, it is easier to identify a heart attack because the symptoms will be like their usual angina except that it is more severe or last for longer than 15 minutes. (However, in those who have had bypass surgery or who are diabetic, the character of their angina may change over time and the symptoms of a heart attack may be different from previous angina).

Unfortunately, the remainder of heart attacks occur in people who have never had angina before and it is harder for them to identify a heart attack. Nevertheless, symptoms do tend to be severe or last longer than 15 minutes.

If anybody is having symptoms which they think could be a heart attack, they should seek immaediate advice by calling 999.

An image of an ambulance. Call 999 if a heart attack is suspected.

ST Elevation Myocardial Infarction (STEMI)

When an ambulance crew sees someone with a suspected heart attack, they will do an ECG. If this shows a feature known as “ST elevation”, the patient will be taken to the nearest hospital that can provide immaediate angioplasty and coronary stenting. It is important that blocked arteries are opened up quickly. Sometimes, coronary bypass surgery or just treatment with medication is required rather than angioplasty.

An image of a blood test. Sensitive blood tests can now detect very small heart attacks.

NSTEMI

In fact, most heart attacks do not have “ST elevation”. When heart muscle dies, a protein known as troponin is released into the blood. There are highly sensitive blood tests that can detect troponin so that even very small heart attacks can be diagnosed. Although immaediate angioplasty is not usually required for patients with Non ST elevation Myocardial Infarction (NSTEMI), cardiac catheterisation and any necessary treatment is done before discharge from hospital.

An image of a cardiac MR scan. MR scans can detect the scar tissue of a heart attack.

MINOCA

Although most heart attacks are due to blocked coronary arteries, some patients have normal arteries. The term MINOCA (myocardial infarction with non-obstructive coronary arteries) has been used to describe these and investigations can be done to look for confirmatory evidence and to look for alternative diagnoses.

Cardiac MR scans are useful because they can identify the scar tissue associated with heart attacks and they can also identify other heart muscle problems.

An image of an octopus. Emotional stress can cause a type of heart attack where the shape of the heart is said to be like a Japanese octopus pot.

Takotsubo Cardiomyopathy

As an example, Takotsubo cardiomyopathy is a type of heart attack where the coronary arteries are normal. Takotsubo is the Japanese name for an octopus pot and the shape of an affected heart is said to have a similar appearance. Takotsubo is sometimes known as “broken heart” syndrome because it is caused by emotional stress such as that associated with breaking up with a partner, death of someone close or doing a sky dive for the first time. Fortunately, heart function usually recovers fully.

An image of an implantable defibrillator in a patient after a heart attack.

Complications

Unfortunately, some patients will develop complications after a heart attack. These include heart failure and abnormal heart rhythms (arrhythmias). These patients may need additional treatments such as a biventricular pacemaker to improve the function of the heart or an implantable cardioverter defibrillator to protect against life threatening arrhythmias.

An image of a patient riding a bicycle.

Secondary Prevention and Cardiac Rehabilitation

Following a heart attack, one aim is to prevent further heart attacks and death. The role of treatments such as statins, aspirin and risk factor control are described in the angina page. For patients treated with a stent, a second blood thinner in addition to aspirin is prescribed. This may be clopidogrel, ticagrelor or prasugrel and the prescription is usually for 12 months.

Cardiac rehabilitation is important too. These are programs of education and graded exercise.

An image of a commuter.

Normal Life

The purpose of treatment following a heart attack is to try and return patients to a life that is as normal as possible. There may be medical or regulatory reasons why a patient cannot drive, travel by plane, resume work or have sex but often, these restrictions are not permanent.

In summary, a heart attack is a medical emergency and anyone who thinks they are having a heart attack should call 999. Timely treatment can prevent deaths and complications. The aim of treatment is to return patients to a normal life.