PVC’s are common. Some people are troubled by just a few PVC’s where as others may have a PVC heart beat almost every other beat and not even notice it. Apart from being annoying to some (symptoms are sometimes described as heart flutter), are they of long-term significance? In this article we will look at some of the studies that examine this question. It appears that the significance of PVC’s depends on the underlying heart. In abnormal hearts such as those with coronary artery disease or heart muscle dysfunction PVC’s are known to be associated with poor outcomes. Whereas in apparently normal hearts, the significance of PVC’s is less well known and certainly thought to be of less concern.
PVC Heart Beats – In Those With Otherwise ‘Normal’ Hearts
In those with underlying heart disease the association between PVC heart beats and poor outcomes is well documented. What about those people that have PVC’s and apparently ‘normal’ hearts otherwise?
In the 1980’s, studies followed relatively small numbers of apparently healthy individuals with frequent PVC’s (around 500/hour) and concluded that they were at no greater risk than the general population. Findings were similar in those who had PVC’s that only appeared following exercise. So it would appear that PVC heart beats were relatively benign in those with otherwise healthy hearts.
Many further studies were done over the years and more recently studies have looked at the combined results of all of these studies that looked at PVC’s in individuals without a history of heart disease. It’s noted that those with PVC’s detected on monitoring had a worse outcome compared to those without PVC’s. However a closer look showed that these worse outcomes were related not necessarily to the PVC’s but may in part be explained by the presence of cardiovascular risk factors such as age, diabetes, and high blood pressure. Also it must be noted that although these studies included individuals without a history of heart disease, the participants did not necessarily have tests to rule it out. Therefore it may well be that those that did worse simply had the presence of undiagnosed heart disease.
Finally, studies have demonstrated that in patients with a particularly high burden of PVC’s (around 25%, 1 in 4 beats) may have subtle heart muscle dysfunction that can be reversed by treatments to ablate the PVC’s. This has led some to advocate treatments for PVC heart beats when the frequency of them is particularly high.
PVC Heart Beats – In Those With Underlying Heart Disease
In patients with underlying heart disease, such as after a heart attack or in those with heart failure, it is well established that those with PVC heart beats do worse than those without. That does not necessarily mean that the PVC ’s are responsible for the poor outcomes but rather a reflection of the underlying heart disease. For example we know that those people that have had a heart attack or heart muscle dysfunction are likely to do worse than those that haven’t, whether or not the PVC’s are present.
So are the PVC’s to blame for the poor outcomes in these patients with underlying heart disease? There is some evidence from studies looking at these populations that PVC’s may lead to heart failure and potentially fatal and non-fatal arrhythmias such as inappropriate sinus tachycardia. One study looking at patients that had a heart attack and also had severely reduced heart function found that the majority of dangerous arrhythmias were started by a PVC heart beat. Its important to note however, use of antiarrhythmic medications to suppress PVC’s in these patients with a heart attack and reduced heart muscle function led to worse outcomes so that strategy was abandoned. Treatment with beta-blockers and in select cases use of implantable defibrillators has been shown to improve outcomes in this population.
In another study, a PVC burden of 25%, basically 1 PVC in every 4th heart beat was associated with heart muscle dysfunction. It was also noted that this dysfunction could be reversed by a procedure to get rid of the PVC’s called an ablation. Numerous studies of patients with reduced heart function but without other structural heart disease have shown that in those with a very high burden of PVC heart beats (typically >20,000 a day) an ablation procedure may be of benefit in improving heart function. Despite this, due to the nature of the studies that were not designed to specifically look at this, it is still difficult to know for sure which came first, the PVC’s or the reduced heart function.
PVC Heart Beats – Summary
Occasional PVC heart beats are common and in general not of concern. The studies in this article are generally concerning those with more frequent PVC’s. In those with underlying heart disease such as coronary disease or heart muscle dysfunction, PVC heart beats are associated with worse outcomes, partly due to the fact that the heart is more diseased to begin with. In these patients treatments are not directed toward the PVC’s, but rather toward the diseased heart and include medications such as beta-blockers and in suitable cases the use of implantable defibrillators. These are measures known to improve outcomes. The exception being those with high PVC burden (i.e. >20%) and muscle dysfunction where treatment of the PVC’s with a procedure may result in improvement of the heart muscle function.
In those without a history of heart disease the relationship between PVC’s and outcomes is less clear and outcomes may be related to the presence of undiagnosed heart disease. In these patients work up may include studies to rule out underlying heart disease such as echocardiography and stress testing. Also important is the treatment of cardiovascular risk factors such as diabetes and hypertension. In very symptomatic patients or those with high PVC burden, i.e. greater than 20% referral should certainly be made to an electrophysiologist to discuss treatment options. In general even those with fairly frequent PVC’s who have had underlying heart disease ruled out can be reassured and likely have a good prognosis.