Abstract
Aging leads to structural and electrophysiological changes that increase the risk of postoperative atrial arrhythmias; however, noninvasive preoperative markers of atrial proarrhythmic conditions are still needed. This study is aimed at assessing whether interatrial dyssynchrony determined using two-dimensional speckle tracking echocardiography relates to proarrhythmic structural and functional remodeling. A cohort of 45 patients in sinus rhythm referred for cardiac surgery was evaluated by echocardiography and surface electrocardiogram the day before the intervention. Transmembrane potential, connexin, and potassium channel distribution, inflammatory, and nitrooxidative markers were measured from right atrial tissue obtained from patients. A difference greater than 40 milliseconds between right and left atrial free wall contraction confirmed the presence of interatrial dyssynchrony in 21 patients. No difference in relation with age, previous diseases, and 2-dimensional echocardiographic findings as well as average values of global longitudinal right and left atrial strain were found between synchronic and dyssynchronic patients. Postoperative atrial fibrillation incidence increased from 8.3% in the synchronic group to 33.3% in the dyssynchronic ones. P wave duration showed no difference between groups. Action potentials from dyssynchronous patients decreased in amplitude, maximal rate of depolarization, and hyperpolarized. Duration at 30% of repolarization increased, being markedly shorter at 90% of repolarization. Only the dyssynchronous group showed early and delayed afterdepolarizations. Atrial tissue of dyssynchronous patients displayed lateralization of connexin 40 and increased connexin 43 expression and accumulation of tumor necrosis factor-α in the intercalated disc. Tumor necrosis factor-α did not colocalize, however, with lateralized connexin 40. Nitroxidative marks and KATP channels increased perivascularly and in myocytes. Our results demonstrate that, as compared to a traditional surface electrocardiogram, the novel noninvasive echocardiographic evaluation of interatrial dyssynchrony provides a better identification of nonaged-related proarrhythmic atrial remodeling with increased susceptibility to postoperative atrial fibrillation.
Highlights
Arrhythmias usually complicate cardiovascular surgery, and aging is the main risk factor
This study is aimed at assessing whether interatrial dyssynchrony, determined by using two-dimensional speckle tracking echocardiography, relates to proarrhythmic structural and functional remodeling of the atria and whether this increases the susceptibility for postoperative atrial fibrillation (POAF)
Our study found that interatrial dyssynchrony assessed by echocardiography was associated with electrical and structural atrial remodeling and the incidence of postoperative atrial fibrillation
Summary
Arrhythmias usually complicate cardiovascular surgery, and aging is the main risk factor. Atrial fibrillation is the most frequent sustained arrhythmia with a peak of appearance between the second and fifth days of the postoperative stay [1]. Postoperative atrial fibrillation (POAF) prolongs hospital stay and increases the risk of stroke and mortality [1]. Hyperadrenergic states, and inflammation contribute to age-related atrial remodeling, but these tissue alterations are challenging to identify noninvasively [3, 4]. In this context, atrial enlargement, stiffness, and conduction blockade are known risk factors, but they are present in only a few patients. The lack of tools to estimate the proarrhythmic substrate evidences the absence of preventive interventions
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