Past studies have linked epicardial fat to a variety of other heart problems, including diastolic dysfunction, atrial inflammation and atrial systolic function disorders.
Buildup of epicardial fat tissue (EFT) is associated with more serious cases of atrial fibrillation (AF), a team of researchers has concluded following a meta-analysis of past studies. They said the findings indicate EFT has predictive value in AF.
EFT is a thin layer of fat sandwiched between the myocardium, the layer of muscular tissue in the wall of the heart, and the inner layer of the pericardium, the sac that surrounds the heart.
Atrial fibrillation is irregular operating rhythm of the heart’s upper two chambers, which can lead to stroke and heart failure. It is treatable with antiarrhythmic drug therapy or, more reliably, catheter ablation, which involves scaring the heart tissue to block faulty electrical signals and induce normal rhythm. However, there is high postoperative recurrence (30% to 50%), and authors of the study concluded EFT volume could help in anticipating recurrence.
Past studies have linked EFT with diastolic dysfunction, atrial inflammation, myocardial deposition, and atrial systolic function disorders. EFT may also modulate metabolic and biochemical functions that contribute to the development of AF.
Lead author Qiankun Fan and other investigators from The First Hospital of Hebei Medical University in Hebei, China, performed a retrospective review of 22 studies to examine the connection between EFT and severe AF.
They found that EFT volume was higher in individuals with AF than in healthy participants.
They also compared EFT volume in healthy individuals versus those with paroxysmal AF (PAF) and persistent AF (PeAF).
PAF is intermittent AF and is considered less severe than PeAF, which is irregular heart rhythm that does not return to normal without treatment.
Healthy individuals had lower EFT than patients with PAF and those with PeAF, according to the findings. Also, patients with PeAF had higher EFT volume than patients with PAF.
Lastly, investigators compared EFT volume between patients who had and did not have AF recurrence following ablation treatment. “The EFT volume of patients with AF recurrence after ablation was greater than that of patients without AF recurrence,” Fan and his co-researchers wrote.
“These results further indicate that EFT is related not only to the occurrence of AF but also to the severity of AF, which strengthens the value of EFT volume as an imaging indicator in clinical work,” they concluded.
Risk factors and conditions associated with AF include coronary heart disease, hypertension, heart failure, diabetes, smoking, age and obesity, but physicians do not know the exact mechanism for the occurrence and development of AF. Some prime suspects are inflammation, oxidative stress, endothelial and microvascular dysfunction, and hypercoagulability, the researchers wrote.
They noted that a long history of AF and severe atrial fibrosis makes it more likely that AF will recur following ablation. “ETF promotes the occurrence of atrial fibrosis and increases AF burden through direct infiltration, secretion of adipocytokines, and induction of inflammatory responses,” Fan and his colleagues wrote.