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The SCVC Blog

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AFib – what investigation?

Posted on Thursday March 7, 2024 in Heart Health

With atrial fibrillation affecting over 10% of people by the age of 70, it is accepted that not every patient with atrial fibrillation needs to be seen by a cardiologist. For the vast majority of patients, their care can be managed perfectly well by the family doctor and their team.

The first consideration when first diagnosed is to classify what type of atrial fibrillation the patient is experiencing. There are three sorts:

1. Intermittent or paroxysmal atrial fibrillation, defined as episodes of the rhythm lasting more than 30 seconds. This is easier to diagnose when the patient has symptoms of palpitation from their arrhythmia, but it is increasingly recognized that many patients with paroxysmal atrial fibrillation are not fully aware of their arrhythmia. It is being detected because of the increasing use of heart rhythm monitors and pulse check equipment in our gyms, routine pulse checks, and blood pressure monitors, all of which have algorithms that raise awareness in the event of an irregular rhythm.

2. Persistent atrial fibrillation, where the heart is incapable of converting the atrial fibrillation back to its normal sinus rhythm. This would be quite normal to happen in the natural history of someone with intermittent or paroxysmal atrial fibrillation over time.

3. The third and most common variety is known as accepted atrial fibrillation, although its previous names, permanent or chronic atrial fibrillation, are useful descriptors. In these cases, it has been accepted by the patient and their cardiologist or GP that they will remain in atrial fibrillation for the rest of their life.

The investigation of each type of atrial fibrillation is slightly different, as there is more of a need for ambulatory ECG monitoring for someone who is intermittently in AF, particularly if they are not fully aware of when it is occurring. However, the main test required in all presentations is a 12-lead ECG, as this will confirm the arrhythmia and also check for any underlying cause, such as left ventricular hypertrophy, cardiomyopathy, or signs of coronary artery disease.

Based on the initial clinical assessment, the physician must then decide the extent of further investigations, depending on whether there are any indicators of underlying conditions, such as hypertension, thyrotoxicosis, or intercurrent illness that may have triggered the atrial fibrillation.

If the patient has minimal symptoms and no other risk factors, then once an ECG is taken, there may not be a need for any other investigations. However, for those patients with associated conditions such as hypertension, coronary artery disease, or significant symptoms from the atrial fibrillation, more extensive investigation is needed. A transthoracic echocardiogram or ultrasound of the heart is an important priority to check the function and the valves. There will be a low threshold for the GP to refer patients to have an echocardiogram if there are any concerns about whether the AF may be a presenting feature of a structural heart problem, such as cardiomyopathy, valve disorders, coronary heart disease, or diastolic abnormalities related to hypertension.

Once inside a specialist cardiology clinic, there are more options available for patients under investigation for their AF. If there is a suspicion that there may be underlying coronary heart disease, then other tests such as exercise treadmill testing and/or CT angiography will be undertaken. Atrial fibrillation often occurs alongside other health issues, which may determine the need for more extensive testing, such as ambulatory blood pressure monitoring to get an accurate idea of home blood pressure. BNP levels are often measured to get a view on how stretched the heart ventricle and atrium may be as a result of the condition.

One of the biggest issues with atrial fibrillation is the dysregulation of the heart’s rate response to exercise. Even in those with permanent or persistent atrial fibrillation, Holter monitoring and exercise testing can be useful in gauging the response to medical therapy aimed at normalizing the heart rate response to exercise, which is an important determinant of well-being for patients. If antiarrhythmic drugs to hold patients in normal rhythm are being considered, then some of these are contraindicated in the presence of coronary heart disease. Many cardiologists will undertake formal CT angiography to ensure that there is no coronary disease that might lead to complications while taking antiarrhythmic drugs.

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