Date Published: June 1, 2018
Publisher: Public Library of Science
Author(s): Hye-Jeong Lee, Jae-Sun Uhm, Yoo Jin Hong, Jin Hur, Byoung Wook Choi, Boyoung Joung, Young Jin Kim, Yoshihiro Fukumoto.
The preexcited myocardium of Wolff-Parkinson-White (WPW) syndrome would have different characteristics from normal myocardium and these findings might be related to persistent left ventricular systolic dysfunction. We evaluated myocardial tissue characteristics at the preexcited segment in adult WPW syndrome patients and their implicated findings.
For this prospective study, we enrolled 22 adult WPW syndrome patients (16 male, mean 45.4 ± 17.8 years) with echocardiographic findings of regional wall motion abnormality in our electrophysiology clinic. Of these patients, 14 underwent radiofrequency ablation before cardiac magnetic resonance imaging. All patients underwent cardiac magnetic resonance imaging including cine and late gadolinium enhancement. The ventricular morphology, function and myocardial characteristics of the preexcited segment were analyzed.
A relatively high prevalence of late gadolinium enhancement (9/22, 40.9%) was observed exclusively at the basal septum. The septal accessory pathway was significantly more prevalent in patients with late gadolinium enhancement (P = 0.011). The prevalences of regional myocardial wall thinning and regional akinesia were significantly higher (P = 0.001 for both) and left ventricular function was significantly decreased in patients with late gadolinium enhancement (P < 0.001). In addition, there were no significant relationships between radiofrequency ablation and regional akinesia (P > 0.999), regional myocardial wall thinning (P > 0.999), late gadolinium enhancement (P = 0.662) and low ejection fraction (P > 0.999).
Myocardial fibrosis was observed at the preexcited myocardium of adult WPW syndrome patients with septal accessory pathway, which could accompany regional akinesia and regional myocardial wall thinning and might be related to persistent left ventricular systolic dysfunction even after radiofrequency ablation.
Wolff–Parkinson–White (WPW) syndrome is defined as a congenital condition involving an abnormal conductive accessory pathway between the atrium and ventricle that bypasses the atrioventricular node [1,2]. This syndrome is of clinical importance because it is frequently associated with supraventricular tachycardia. Furthermore, sudden cardiac death is potentially possible due to ventricular tachyarrhythmia from the associated atrial fibrillation with rapid anterograde conduction over the accessory pathway [3,4]. In addition, a rare cause of morbidity in WPW syndrome patients is heart failure, which may occur as a result of recurrent or sustained tachyarrhythmia . Recently, several literatures have reported a possible direct association between WPW syndrome and heart failure, regardless of the related tachyarrhythmia [6–10]. Eccentric ventricular preexcitation through the accessory pathway results in premature contraction of that ventricle, and this has been well documented in echocardiography [11,12]. Regional premature contractions are thought to be a possible mechanism for heart failure in WPW syndrome by inducing progressive ventricular dilatation with cardiac dysfunction similar to functional aneurysm [6,13]. In addition, heart failure in WPW syndrome has been associated with the septal accessory pathway and has a reversible nature with a temporal relation after radiofrequency ablation (RFA) of the septal accessory pathway [7,8,10,14]. Cardiac magnetic resonance imaging (CMR) is a rapidly evolving technology that might now be the most powerful imaging tool for noninvasive myocardial characterization through the late gadolinium enhancement (LGE) and T1 mapping technique. Recent research has supported the value of these techniques for the assessment of myocardial characteristics under multiple conditions [15,16]. We thought that the preexcited segment in WPW syndrome could have different myocardial characteristics from the normal myocardium, especially in adult patients who are exposed to the accessory pathway for a long period of time, and we thought that the different characteristics could be related to left ventricular systolic dysfunction. However, as far as we know, CMR findings for myocardial characterization in WPW syndrome patients have rarely been studied. Therefore, we evaluated the myocardial characteristics of the preexcited segment using CMR in adult WPW syndrome patients and their implicated findings through this study.
We evaluated myocardial characteristics of the preexcited myocardium using CMR in adult patients with WPW syndrome. In our results, we observed a relatively high prevalence of LGE in the study participants (9/22, 40.9%) exclusively at the basal septum. The prevalence of septal accessory pathway was significantly higher in patients with LGE. In addition, the prevalences of regional myocardial wall thinning and regional akinesia were significantly higher in patients with LGE. Left ventricular end-diastolic volume was significantly larger and both ventricular ejection fractions were significantly decreased in patients with LGE. The native T1 value and extracellular volume fraction were significantly increased in patients with LGE, especially at the septum, which might support the presence of myocardial fibrosis. In addition, there were no significant relationships between RFA and abnormal CMR findings such as regional akinesia, regional myocardial wall thinning, LGE and low ejection fraction in the present study.
We observed a relatively high prevalence of myocardial fibrosis at the preexcited myocardium of adult WPW syndrome patients, exclusively at the basal septum with septal accessory pathway in the present study. In some cases, myocardial fibrosis accompanied regional akinesia and regional myocardial wall thinning. These abnormal findings might have occurred from continuous premature contractions by the septal accessory pathway and might be related to persistent left ventricular systolic dysfunction even after successful RFA. A further prospective study using CMR with a large population is necessary to identify myocardial characteristics at the preexcited myocardium in WPW syndrome, which might provide new perspectives for the disease and help develop management strategies in the future.