By Harold L. Karpman, MD, FACC, FACP
Clinical Professor of Medicine, UCLA School of Medicine
Dr. Karpman reports no financial relationships relevant to this field of study.
SYNOPSIS: In a population-based sample, a higher frequency of premature ventricular contractions was associated with a decrease in left ventricular ejection fraction, an increase in incident congestive heart failure, and an increase in mortality.
SOURCE: Dukes JW, et al. Ventricular ectopy as a predictor of heart failure and death. J Amer Coll Card 2015;66:101-109.
The effect of premature ventricular contraction (PVC) frequency on left ventricular systolic function, incident congestive heart failure (CHF), and/or mortality in the general population remains unknown. Because of individual variations in the frequency of PVCs during a 24-hour period, Holter monitoring for at least 24 hours is essential to accurately assess the frequency of daily PVCs and to attempt to determine which periodic events may contribute to the true PVC burden.1,2 Dukes et al3 used a 24-hour Holter monitor to ascertain PVC frequency in an attempt to determine if PVC frequency was a predictor of a decrease in the left ventricular ejection fraction (LVEF), incident CHF, and/or death in a population-based cohort study.
Dukes et al studied 1139 Cardiovascular Health Study participants who were randomly assigned to 24-hour ambulatory electrocardiography monitoring and who had a normal LVEF and no history of CHF. PVC frequency was quantified using Holter studies, and LVEF was measured from an echocardiogram recorded at baseline and on echocardiograms obtained 5 years later in participants who were followed for incident CHF and/or death. Participants who were in the upper quartile vs the lower quartile of PVC frequency had a multivariable-adjusted three-fold greater odds of a 5-year decrease in LVEF, a 48% increased risk of developing incident CHF, and a 31% increased risk of death during a median follow-up of > 13 years. The specificity for the 15-year risk of CHF exceeded 90% when PVCs comprised at least 0.7% of the total number of heartbeats. The positive predictive value for the 15-year risk of incident CHF was > 50% when the percentage of PVCs was between 1.24% and 3.55% of all cardiac beats.
COMMENTARY
The results of the Dukes study are very important in that they demonstrate that a higher frequency of PVCs is associated with a significant decrease in LVEF, an increase in incident CHF, and an increase in mortality, which is at least partly explained by the increased frequency of CHF. These findings are quite important because CHF currently affects more than 5 million Americans and its prevalence is expected to increase by 25% within the next 15 years.4 Equally important, up to 50% of CHF cases have no known etiology.5 Some known risk factors for CHF, such as advanced age, are not treatable; however, other risk factors, such as hypertension, obesity, and some effects of progressive coronary artery disease, are treatable. The results of the Dukes study suggest that PVCs may be an important cause of an occult or “idiopathic” cardiomyopathy, which may lead to CHF and an increased incidence of cardiovascular death; however, one cannot exclude the possibility that the presence of PVCs may be a marker of an abnormality in people who have occult cardiomyopathy of any etiology. The mechanism by which frequent PVCs lead to systolic dysfunction remains unknown; however, the available evidence favors adverse ventricular remodeling that occurs due to repeated dysynchrony.10,11 Furthermore, recent studies have demonstrated that systolic dysfunction in patients with CHF may improve and be resolved after successful ablation of high-burden PVCs.6-9 At this time, recognizing that there is a high prevalence of PVCs in the general population, there is no scientific proof that suppressing the high prevalence of PVCs will reduce the incidence of CHF and improve longevity. Certainly, this is the question that should be answered by setting up a properly structured, carefully controlled study to determine if the suppression of the high incidence of PVCs in the general population will reduce the incidence of CHF and/or cardiovascular death in the general population.
For the time being, clinicians should be aware of the results of the Dukes study and decide whether to consider treating excessive numbers of PVCs, which they have determined to be present in individual patients, with medical or ablation therapy, although the research results that would mandate such therapy are not available as yet and future research is required before entertaining this treatment approach in clinical practice.
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