Among the many different types of cardiac arrhythmias, few have created as much consternation and confusion - among both doctors and patients - as premature ventricular complexes (PVCs), also called premature ventricular contractions. In various doctors’ offices, and at various points in history, PVCs have been regarded as either harbingers of impending death or as completely benign phenomena that require no attention whatsoever.
The right answer is somewhere between these two extremes.
In this article we will review PVCs -- what they are, what they imply in terms of medical prognosis, how they ought to be evaluated and how they ought to be treated.
What Are PVCs?
A PVC is an extra electrical impulse arising from one of the cardiac ventricles, usually the left ventricle. PVCs are diagnosed by recording an ECG or some other form of heart rhythm monitoring, such as a Holter monitor.PVCs are quite common. Around one in 20 normal people will have at least one PVC on a two-minute ECG strip, and a much higher percentage will have PVCs on 24-hour Holter monitoring.
Some people will have episodes of several PVCs in a row. If there are more than three PVCs in a row, the episode is called non-sustained ventricular tachycardia (NSVT).
Symptoms of PVCs
Most people with PVCs have no symptoms at all. They simply don't feel them. However, a substantial minority of people with PVCs will perceive palpitations - an unusual awareness of the heart beat. These palpitations are often described as "skipped beats" or a "pounding heart." In some people, these symptoms are extremely difficult to tolerate.Whether you perceive symptoms from your PVCs is related to many factors. Some people are just naturally more sensitive to any unusual events that occur in their internal organs - including PVCs. Others are blissfully unaware of their PVCs during the day when they are active and distracted, but suddenly begin to feel them when they retire for the night and external stimuli are removed. But fortunately, most people do not feel them at all.
Why Are PVCs Significant?
PVCs have medical significance beyond the fact that they can produce symptoms. Over the years, the chief concern about PVCs is that they may increase a person's risk for sudden death from cardiac arrest. For decades, it was believed that the presence of PVCs significantly elevated that risk. More recently, evidence has suggested that the actual PVCs themselves may not increase the risk of sudden death very much, and that the association between PVCs and sudden death may be an indirect one.Specifically, it turns out that people who have frequent PVCs are more likely to have a significant underlying heart problem and also appear to have an increased risk of developing significant heart disease within a few years. And because people who have significant heart disease do indeed have a higher risk of sudden death, PVCs are therefore associated with that same risk.
How Should PVCs Be Evaluated?
The chief medical significance of PVCs is that they may indicate either that heart disease is present or the risk of developing heart disease is elevated. So when PVCs are discovered, your doctor should launch an evaluation, looking for previously unknown heart disease and assessing your risk of developing heart disease in the future.The heart diseases most often associated with PVCs include coronary artery disease (CAD) and heart failure due to dilated cardiomyopathy. PVCs are also commonly seen with hypertrophic cardiomyopathy, and with heart valve disease.
In general, an echocardiogram is a good way to screen for most of these diseases, although your doctor may also want to perform a stress thallium test to check for CAD.
In addition, you and your doctor should go through a formal risk assessment including evaluating your diet, weight, smoking history, exercise habits, cholesterol and triglyceride levels, blood pressure and blood glucose evaluation.
Aren't the PVCs Themselves Dangerous?
The best information we have today suggests that PVCs themselves are only very rarely dangerous.On the other hand, in some people the presence of PVCs indicates an inherent electrical instability in the heart and, therefore, indicates an increased risk of sudden death. This increased risk associated with PVCs, in general, is limited to patients with significant underlying heart disease, or with a high risk of develping heart disease.
But even in these cases, the PVCs themselves do not appear dangerous. We know this because studies have shown that suppressing the PVCs does not reduce the risk of dying, and in fact (depending on which antiarrhythmic drug is used), often actually increases that risk.
So only rarely is it ever necessary, or even desirable, to attempt to get rid of the PVCs.
Treating People with PVCs
From the above discussion, it should not be a surprise that treating PVCs isn't entirely a straightforward endeavor. In fact, doctors often get a little confused about what they are supposed to do when one of their patients has PVCs - especially when those PVCs are producing a lot of symptoms.Sources:
Zipes, DP, Camm, AJ, Borggrefe, M, et al. ACC/AHA/ESC 2006 Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death-Executive Summary A Report of the American College of Cardiology/American Heart Association Task Force and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Develop Guidelines for Management of Patients With Ventricular Arrhythmias and the Prevention of Sudden Cardiac Death). J Am Coll Cardiol 2006; 48:1064.
