Irregular heart rhythms linked to higher risks for PAH patients in US study
Identifying those with too fast, out of sync heartbeats may help improve care
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Irregular heart rhythms such as atrial fibrillation, which can make the heart beat too fast, and atrial flutter, which causes the heart to beat out of sync, are relatively common in people with pulmonary arterial hypertension (PAH), a new study in the U.S. suggests.
Both types of irregular heart rhythms, or arrhythmias, were linked to a higher risk of death or the need for a transplant, in addition to poorer survival rates, according to the researchers.
The team found that changes in the right side of the heart, including enlargement and reduced pumping function, were associated with a greater likelihood of developing these abnormal rhythms.
As such, identifying such structural and functional changes in the right side of the heart may help doctors identify individuals who are at higher risk of poorer results, “potentially improving clinical outcomes,” the researchers wrote.
The study, “Incident Atrial Fibrillation and Flutter in Patients With Pulmonary Arterial Hypertension: Influence of Right Ventricular Dilatation and Reduced Right Atrial Function,” was published in the Journal of the American Heart Association, or JAHA.
A type of pulmonary hypertension, PAH is a condition in which the pulmonary arteries, the blood vessels that carry blood from the heart to the lungs, become narrowed. This increases pressure in those vessels and forces the right side of the heart to work harder to pump blood.
Over time, this strain can cause the right ventricle — the chamber that pumps blood to the lungs — to thicken and, as the disease progresses, enlarge and weaken.
These changes can also affect the right atrium, the chamber that receives blood returning to the heart and pumps it into the right ventricle. As it stretches, it becomes less efficient at moving blood forward, which may disrupt the heart’s electrical signals and increase the risk of irregular heart rhythms.
Investigating right-side heart issues in people with PAH
In left-sided heart disease, similar changes in the left side of the heart are already known to increase the risk of atrial fibrillation and atrial flutter. These arrhythmias have also been linked to a higher risk of death.
However, less is known about how changes in the right side of the heart contribute to these rhythm problems in people with PAH.
To explore this, the team analyzed data from 326 adults with PAH who had no prior history of atrial fibrillation or flutter. The patient data were drawn from two U.S. registries: the Minnesota Pulmonary Hypertension Repository, which has enrolled people treated for pulmonary hypertension since 2014, and the Stanford University’s Pulmonary Hypertension Registry, which followed people with PAH between 2002 and 2021.
The individuals in the study were mostly women (79%) and had a mean age of 51. Overall, the patients had severe disease, with high pressure in the pulmonary arteries, reduced heart function, and limited exercise capacity. The mean REVEAL Lite score — a measure used to estimate survival in people with PAH — was 7.4, indicating intermediate risk of poor outcomes.
Heart imaging showed clear strain on the right side of the heart, with enlargement and reduced function of both the right atrium and right ventricle. Among the patients, the left side of the heart was largely normal.
Over a median follow-up of about six years, 56 patients (17.1%) developed atrial fibrillation or flutter, corresponding to 25.3 cases every 1,000 people per year. Most (87.5%) had atrial fibrillation and 12.5% atrial flutter.
After adjusting for factors such as age, sex, heart function, and REVEAL Lite score, individuals who developed these arrhythmias had a 1.7 times higher risk of death or the need for a transplant, data showed.
Survival was also significantly lower after the onset of these rhythm disorders, the researchers noted. Survival rates were 73% at one year, 57% at three years, and 48% at five years, compared with 91%, 80%, and 75%, respectively, in participants who did not develop such arrhythmias.
ID’ing irregular heart rhythms could enable earlier monitoring
After accounting for multiple variables, right ventricular basal diameter — a measure of right ventricle enlargement — and right atrial emptying fraction, which reflects how well the right atrium pumps blood into the right ventricle, were the only factors independently associated with increased risk of developing these arrhythmias, the researchers noted.
Each 1 cm increase in right ventricular size raised the risk by about 55%, while each 5% decrease in right atrial function increased the risk by about 38%, the data showed.
Both measures showed similar overall ability to predict the risk of developing arrhythmias. However, further analysis suggested that right ventricular enlargement may play a more central role, the scientists noted.
A right ventricular basal diameter of 5.4 cm or greater emerged as a key threshold for predicting risk. Among patients with this level of enlargement, even mild reductions in right atrial function were linked to a higher risk of atrial fibrillation or flutter. In contrast, among patients without right ventricular enlargement, only more severe impairment in right atrial function — lower than 17% — was associated with increased risk.
Consistent with these findings, patients with either an enlarged right ventricle of 5.4 cm or greater or reduced right atrial function lower than 17% had more than a threefold higher rate of arrhythmias, while those with both abnormalities had more than a sixfold higher risk. These individuals were also less likely to remain free of arrhythmias over time.
“Larger right ventricular basal diameter and lower [right atrial] emptying fraction are associated with increased risk of incident [atrial fibrillation/atrial flutter] in patients with pulmonary arterial hypertension and may help identify individuals at higher risk,” the researchers concluded.
The team noted that “these findings may … [enable] earlier monitoring and potential intervention.”
