1. What are premature beats?

Premature beats, also known as premature contractions, are the most common arrhythmias in clinic. Under normal circumstances, the heartbeat is originated from a tissue called sinoatrial node in the upper lateral part of the right atrium, so the normal rhythm is called sinus rhythm. If there is a lesion at any other position of the heart that releases electrical impulse due to inflammation, ischemic necrosis, fibrosis or other reasons, it will make ectopic beats occur before sinus rhythm. Those ectopic beats are referred to as premature beats, or premature contractions.

2. What are the types of premature beats?

Premature beats contain different types of classifications. In general, the most frequently used classification is based on the site of origin. Atrial and ventricular premature beats are the most common, and there are also atrioventricular junctional premature beats. Of course, both the atrial and ventricular premature beats can be further divided into left originated or right originated. Moreover, there are some more detailed classifications of premature beats, for example, atrial premature beats originated from left superior pulmonary vein, ventricular premature beats originated from right outflow tract, etc. In addition, premature beats can also be classified according to their degree or morphology. Different types of premature beats may have different influence on health conditions, symptoms and treatment strategies of patients.

3. What are the symptoms of premature beats?

In majority of cases, premature beats are characterized by a sense of intermittent heartbeat. Many patients even don’t have obvious symptoms, and they are diagnosed by accident in their routine physical examinations or because of other associated diseases. It should be pointed out that many people go to see doctors because of some uncertain symptoms, such as chest distress, insomnia, etc., and they happen to be diagnosed with premature beats. Therefore, both doctors and patients themselves are likely to blame these symptoms on premature beats, but in fact, this is often a wrong judgment. For example, many menopausal women who suffer from anxiety, chest tightness, fever, or sweating were detected with dozens to thousands of premature beats. They should be recommended to do gynecological, endocrine or psychological examinations instead of just attributing all their discomfort to premature beats.

4. How to diagnose premature beats?

The premature beat and its origin can be easily diagnosed by 12-lead ECGs. Of course, 24-hour ambulatory ECGs will help doctors to know the number of premature beats and the characteristics of their time distribution. However, it is the ordinary 12-lead ECG that plays an important role in evaluating the type and location of premature beats. In order to achieve more accurate judgment, it’s better to conduct more 12-lead ECGs and make sure that each lead captures the associated premature beats. In addition, echocardiography should be performed to determine structural lesions of the heart. Generally speaking, it is more necessary to treat premature beats caused by cardiac diseases, but it should also depend on the specific situation of patients. A few patients need to run CT, MRI, even gene or immune tests in order to aid diagnosis.

5. What is the harm of premature beats?

The vast majority of premature beats are not life-threatening, especially atrial premature beats. However, the existence of premature beats will disturb the normal sequence of cardiac contraction, which may affect the cardiac ejection function, leading to various discomforts, but most of them are not serious. In fact, many people come to see doctors mainly because they are worried about the potential risks of premature beats. Some patients may suffer from cardiac enlargement or even heart dysfunction due to frequent ventricular premature beats (such as ≥10000 times premature beats per day for a long time), and annual evaluation of echocardiography should be recommended. In addition, premature beats can also be caused by cardiomyopathy. Therefore, the premature beat and cardiomyopathy interact as both cause and effect, and it only can be determined by reevaluating echocardiography and ECG, 3-4 months after the ablation or drug control of premature beats.

Ventricular premature beats will rarely trigger ventricular fibrillation or even sudden death, which is usually caused by diseases with congenital genetic variation (Brugada syndrome, long QT syndrome, arrhythmogenic cardiomyopathy, etc.) or ECG abnormalities such as QT prolongation resulting from electrolyte disorder and other associated drugs. In addition, R on T phenomenon, as well as premature ventricular contractions with special origins are in high risk of inducing ventricular fibrillation, especially during summer when too much sweating and abnormal eating lead to hypokalemia in patients. The specific situation of different patients needs to be judged by arrhythmia specialists.

6. What lead to premature beats?

The most common cause of premature beats is aging. In other words, the occurrence of atrial premature beats in the elderly is almost inevitable. We can often see some 70 or even 80-year-old patients who are in panic because of atrial premature beats or a small amount of ventricular premature beats. They go to seek medical treatment everywhere and take a lot of drugs. In fact, it is quite unnecessary. For the elderly, premature beats, like white hair, wrinkles or senile plaques, are the manifestations of aging of body organs. Most of the premature beats are not life-threatening, so they can be referred to as benign premature beats, which do not require special treatment, and no medicine can cure them. Unfortunately, some patients are ignorant and disrespectful of science, and their over treatment even leads to complications and death.

Another cause of premature beats is myocardial damage due to ischemia, infection, inflammation and so forth. Under normal circumstances, the cardiac muscle will not release electrical impulse to induce premature beats. Once it does, it suggests that there might be some lesions in certain part of the heart, which is just like moles on the smooth skin, or the remaining spots of fruits and vegetables after frost. Therefore, despite natural aging, we should try our best to have good diets and regular living habits, so as to avoid damages of the immune system and various cardiac inflammatory reactions predisposing to premature beats or even cardiomyopathy. Different kinds of metabolic diseases (diabetes, hyperthyroidism, or hyperlipidemia), as well as cardiac disorders (hypertension, coronary heart disease, myocarditis or cardiomyopathy) are all potential risk factors of premature beats.

Another notable inducement of premature beats is alcoholism. Long-term drinking will cause a series of damages to the heart, liver and brain, leading to arrhythmias such as premature beats, tachycardia, atrial fibrillation, heart failure, and even death.

However, the majority of patients with premature beats (especially ventricular premature beats) are often unable to find out the clear etiology. Most of these patients are likely to be caused by residual lesions of repeated myocarditis. Fortunately, these lesions are usually local pathological changes and do not worth too much worry.

7. How to treat premature beats?

As mentioned above, most premature beats (especially atrial premature beats) are not dangerous or life-threatening. Therefore, patients should consult arrhythmia specialists after the detection of premature beats. A few patients with potentially lethal problem should be treated actively, including catheter ablation or even ICD (implantable defibrillator) implantation.

Ordinary patients can be divided into several situations: if the number of atrial or ventricular premature beats is within 5000 times/day, evaluated as benign, and symptoms of patients are not obvious, then no special treatment or appropriate drug control is recommended (Amiodarone should be avoid in principle, because it not only can't cure premature beats, but also has many side effects).

If the number of ventricular premature beats is more than 10000 times/day, catheter ablation can be considered, but it also depends on the patient’s cardiac function, overall physical condition, as well as the location of premature beats.

Despite the number of atrial premature beats, ablation is not recommended. Because atrial premature beats can have multiple origins, and are usually difficult to be induced during electrophysiological examination, it’s hard for doctors to achieve complete ablation. Excessive pursuit of efficacy may lead to risks during procedure, and the loss may outweigh the gain.

Relatively speaking, the frequent ventricular premature beats can be eliminated by ablation. But it also depends on the location of premature beats and the experience of doctors. In fact, even for ordinary ventricular premature beats which cause cardiac enlargement, heart failure or ventricular fibrillation, ablation should not be excessive. Otherwise, it will cause great long-term damage to the patient's ventricles. Sometimes, the origins of ventricular premature beats may be close to the conduction system or near the coronary artery, which may lead to the incompletion of ablation, but that is the result of carefully weighing benefits and risks.

This article is copyrighted by Dr. Yao Yan. Please do not reprint it without permission.