Estimated survival in patients with either pulmonary arterial hypertension (PAH) or chronic thromboembolic pulmonary hypertension (CTEPH) is worse if they also have atrial arrhythmias, according to a new U.S. study.
The study, “Atrial arrhythmias are associated with increased mortality in pulmonary arterial hypertension,” was published in the journal Pulmonary Circulation.
Atrial fibrillation and flutter (AF/AFL), two types of atrial arrhythmia — changes in the heart’s normal rhythm occurring in one of its two upper chambers, the left or right atrium — are well-known complications of PAH.
Prior studies in European patients reported that the incidence of AF/AFL increased from up to 11-13% within one year of PAH diagnosis to up to 25.1% after five years. Atrial arrhythmias were associated with worsened PAH prognosis and functional class, an indication of how affected the patients are by the disease.
Researchers suggested that this may be due to persistent loss of coordinated atrial contraction in an already fragile heart. Accordingly, restoration of a normal heart rhythm improved long-term survival in PAH patients.
Despite these findings, clinicians still don’t know whether isolated diagnoses of intermittent — characterized by the sudden start and stop of episodes — rather than more constant AF/AFL, may still correlate with increased death in the absence of uncontrolled heart rate.
Additionally, these arrhythmias have not been studied in detail with the advent of modern PAH therapies and management, nor have they been assessed in North American patients. Different guidelines and demographics could lead to different results in this patient population, the authors said.
To address this, scientists at the University of Pittsburgh conducted a multicenter, regional study to determine the clinical characteristics of AF/AFL in PAH and CTEPH — a rare type of pulmonary hypertension caused by the accumulation of blood clots in the lungs’ blood vessels.
They also evaluated whether intermittent or more permanent arrhythmias are associated with poorer survival.
The team identified 297 patients with PAH or CTEPH, classified as Group 1 according to World Health Organization ratings (least severe), who were seen between 2010 and 2014 at the University of Pittsburgh School of Medicine’s hospitals.
Of these patients, 79 (26.5%) experienced AF/AFL at some point, approximately half of which were intermittent. AF/AFL was identified after PAH diagnosis in 42 patients (53.2%), prior to PAH diagnosis in 27 (34.2%), and at an undetermined time in the remaining patients.
Compared with patients without AF/AFL, those with atrial arrhythmias were older (a mean age of 61.8 versus 56), more often male (53.2 versus 25.2%), had lower left ventricular ejection fractions — which indicates how much blood the left ventricle pumps out with each contraction — and an enlarged left atrium of the heart — previously identified as predicting outcome in PAH, AF, stroke and heart failure patients.
The team considered the association between men and AF/AFL “notable,” since clinical data show that women are more prone to develop PAH but have increased survival.
Of note, patients with atrial arrhythmia identified after a PAH diagnosis also showed a greater incidence of congestive heart failure.
Most patients with AF/AFL (86%) were treated with medications to normalize the heart rate and rhythm — anti-arrhythmic and blockers of the atrioventricular node, a major element in the heart’s conduction system.
Of significance, in patients with either PAH or CTEPH and AF-AFL — both intermittent and more constant forms — estimated survival was worse than in those without these arrhythmias, corresponding to an approximately 3.8-fold greater risk of death. This risk persisted even after accounting for potential confounding variables, including structural and heart rate indices.
“In these PAH/CTEPH patients, presence of AF/AFL significantly increased mortality risk,” the scientists concluded.
Future studies should explore these mechanisms “and interrogate whether other therapies beyond rate and rhythm control are necessary to mitigate this risk,” the team wrote. In addition, specialized recommendations for these patients, which are lacking in the U.S. and Europe, could result from further studies, they suggested.