On PVCs, think anew but think slowly

Premature ventricular complexes (PVCs) remain a common and vexing problem in cardiology. PVCs deserve attention because they often induce fear in both patient and doctor. In US healthcare, fear is bad. Fear sets the stage for over-treatment.

The approach to the funny-looking beats has not changed much in the last two decades.

That may be changing. Cardiology is beginning to see PVCs in a different way.

First the current approach:

We begin by asking: “What company do the skipped beats keep?”

Old teaching had it that PVCs in the setting of a normal heart were benign. Don’t worry about them. Reassure the patient; remove or decrease irritants (stress, sleep issues and alcohol, for instance); treat symptoms and essentially let time pass. Benign PVCs usually go away.

(I have written about benign PVCs here: Benign PVCs: A heart rhythm doctor’s approach.)

Old teaching also had it that PVCs occurring in the setting of heart disease were not something we did anything about. The abnormal beats were thought to be mere markers of the underlying disease rather than a modifiable condition. For example, in a patient with heart failure who has frequent PVCs, the teaching was to treat the heart failure, and as that improved, so would the PVCs.

In medical speak, we said PVCs in patients with heart disease were a “non-modifiable epi-phenomenon.”

The reason cardiology feels this way about PVCs in the setting of heart disease stems from a large study in the 1990s called the CAST trial. Back then, we thought suppression of PVCs would help patients, especially those who had a heart attack. To most everyone’s surprise at the time, patients with PVCs after a heart attack who were given drugs to suppress the PVCs did indeed have fewer PVCs, but they also had a higher death rate!

Other studies confirmed the notion that drugs for PVCs reduced the number of PVCs, but did not reduce the death rate from heart disease. Hence the non-modifiable thinking.

Ideas in cardiology change slowly. A recent study, and its accompanying editorial, published in the Journal of the American College of Cardiology tempts us to change our thinking about PVCs.

Before I tell you about these writings, it’s best to set out the present-day context in which cardiology sees heart rhythm problems. In 2015, we (generally) favor catheter ablation of rhythm problems over drug suppression. We also benefit from technology that allows us to see both structural and electrical abnormalities of heart muscle more clearly. MRI scans can show small areas of scar and GPS-like maps in the EP laboratory can identify and color-code areas of abnormal electrical properties. It is amazing technology.

In that context, the short story of the new study and editorial is that, in some cases, PVCs may herald the development of heart failure. That wasn’t so important in the past because there was little we could do about them. But now, with the advent of advanced imaging and improved ablation technology, PVCs may be modifiable. This change in thinking also has huge public health implications as millions of Americans have heart failure.

Please note the modifiers in the previous paragraph. PVCs may herald heart failure…in some cases. The study had serious limitations. It could only show weak associations; we cannot say PVCs cause heart failure. Also note that I said PVCs may be modifiable with ablation. We don’t know yet. Yes, most electrophysiologists have done beautiful cases in which we reverse heart failure by burning a PVC focus that was responsible for tens of thousands of daily PVCs. But these are special cases, done in patients with known heart failure due to the PVC.

You know me. I like to take a cautious slow approach to new thinking, especially when it involves exuberance over invasive procedures. I’ve learned over the decades that when cardiologists are exuberant, it is often irrational or premature exuberance.

Here is my cautionary post over at theHeart.org|Medscape Cardiology:

PVCs: Modifiable Risk Factor for Heart Failure . . . Maybe

JMM

2 comments

  1. “I’ve learned over the decades that when cardiologists are exuberant, it is often irrational or premature exuberance.”

    I’d go so far as to extend this to all specialties, or even to most non-medical fields. Hopes for success and potential profit seem to cloud our ability to anticipate potential problems from new technologies.

  2. Dear dr John,
    What about PVC’s and the risk of sudden cardiac death in a normal heart? The majority of patients have well fewer PVC’s than the number shown to increase the risk of cardiomiopathy, still physicians are concerned about their risk of malignant VT.
    In this respect, I recently read the article of Viskin et al “Cardiologists’s worst nightmare”: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1475953/
    What’s your opinion? Should we be concerned about other factors such as PVC’s origin or coupling interval?

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