Multifocal atrial tachycardia (MAT): causes, symptoms and treatment

The NHS explains that heart rhythm problems (arrhythmias) happen when there is a fault with the electrical system that makes the heart beat, and that the heart may beat too quickly, too slowly or unsteadily. Multifocal atrial tachycardia is one specific kind of fast, irregular rhythm.

Normally the heart's signals begin in the sinus node, the heart's natural pacemaker in the upper right chamber. MedlinePlus explains that in people with MAT, many locations in the atria fire signals at the same time. Too many signals lead to a rapid heart rate, which can make the heart work too hard and not move blood efficiently, because the chambers have less time to fill between beats. When the rate is under 100 beats per minute, MedlinePlus says the rhythm is called wandering atrial pacemaker.

The term multifocal refers to the several sites the beats come from. Because the rhythm is fast and irregular, it needs an ECG recording and a clinician's interpretation to identify.

MAT is rarely a problem on its own. MedlinePlus says it is often seen in people with conditions that lower the amount of oxygen in the blood, and lists chronic obstructive pulmonary disease (COPD), heart failure, lung cancer, lung failure, pneumonia and pulmonary embolism. It adds that a person may be at higher risk if they have coronary heart disease, diabetes, had surgery within the last 6 weeks, have sepsis, or have overdosed on the drug theophylline.

More broadly, the NHS lists conditions that can cause heart rhythm problems, including high blood pressure, coronary heart disease, heart valve disease and heart attack, and says an abnormal heartbeat can also come from medicines, viruses, caffeine, alcohol, smoking or drugs. These apply to arrhythmias in general rather than to MAT specifically.

MedlinePlus says some people have no symptoms. When symptoms occur, it lists chest tightness, fainting, lightheadedness, a sensation of the heart beating irregularly or too fast (palpitations) and shortness of breath. Because MAT often occurs alongside lung or heart disease, symptoms such as breathlessness can be hard to separate from the underlying illness.

The NHS heart rhythm advice says to see a GP if you think you may have heart rhythm problems or if palpitations keep happening or are getting worse. It says to call 999 or go to A&E if you currently have palpitations with chest pain, shortness of breath, feeling dizzy or lightheaded, or fainting or feeling like you might faint. If those symptoms have stopped, it advises asking the GP surgery for an urgent appointment, calling 111 or using 111 online, and not driving yourself to A&E.

MedlinePlus says the tests used to diagnose MAT are an electrocardiogram (ECG) and, in some cases, an electrophysiologic study. Heart monitors may be used to record the rapid heartbeat, including a 24-hour Holter monitor and portable long-term loop recorders that allow the person to start recording when symptoms occur. If you are in hospital, your heart rhythm will be monitored around the clock, at least at first.

The NHS heart palpitations page explains that an ECG uses small pads stuck to the skin to check the electrical signals from the heart, and that you may be referred to a heart specialist (cardiologist) for tests and treatment. Because MedlinePlus says the underlying condition should be treated first, clinicians will also consider what might be driving the rhythm, such as a lung or heart condition or a medicine.

MedlinePlus is clear that the first step is to treat any condition that can lead to MAT. The treatments it lists are shown below. Which apply depends on the cause and on how unwell the person is, so they are chosen by the treating team, often in hospital.

MedlinePlus says MAT can be controlled if the condition causing the rapid heartbeat is treated and controlled. Possible complications it lists are cardiomyopathy, heart failure and reduced pumping action of the heart, and it advises contacting a health professional if you have a rapid or irregular heartbeat with other symptoms, or if symptoms get worse or new ones appear. To reduce the risk of developing MAT, it advises treating the disorders that cause it promptly.

Because MAT is linked to other conditions, the outlook depends largely on how well the underlying illness is treated and controlled. The NHS palpitations page adds that avoiding things that can trigger palpitations, such as stress, smoking, caffeine and alcohol, can help when palpitations are not caused by a health condition.

MedlinePlus says that if you are in hospital your heart rhythm will be monitored 24 hours a day, at least at first, and MAT is linked to other significant illnesses, so it may be found during hospital care. Follow-up with the GP, a respiratory team or cardiology depends on the underlying cause.

A private cardiology consultation can arrange ECGs, ambulatory rhythm monitoring and echocardiograms, which some people use for speed or reassurance. The treatment principles are the same in either sector, and because the rhythm usually reflects another illness, it helps to make sure the team treating that illness is aware of the rhythm diagnosis.

There is no dedicated NHS or UK charity patient page for multifocal atrial tachycardia that could be read for this article. The condition-specific facts come from MedlinePlus, a US National Library of Medicine resource, and the UK advice on symptoms, tests and emergency action comes from the NHS pages on heart rhythm problems and heart palpitations. If you have been told you have MAT, your own clinician is the best source for what applies to you.