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Risk assessment of pre-excitation: Atrial fibrillation versus atrial flutter

  • Jonathan Uniat
    Correspondence
    Address reprint requests and correspondence: Dr Jonathan Uniat, Children’s Hospital Los Angeles, 4650 Sunset Blvd, MS #34, Los Angeles, CA 90027.
    Affiliations
    Division of Cardiology, Children’s Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, California
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  • Michael J. Silka
    Affiliations
    Division of Cardiology, Children’s Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, California
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Open AccessPublished:October 06, 2022DOI:https://doi.org/10.1016/j.hrcr.2022.10.003

      Keywords

      Key Teaching Points
      • Owing to concealed conduction, the shortest pre-excited R-R intervals during atrial fibrillation and atrial flutter may differ significantly.
      • Either atrial fibrillation or atrial flutter may be a substrate for sudden cardiac death for individuals with ventricular pre-excitation.
      • Pediatric patients with Wolff-Parkinson-White disease have a higher incidence of sudden cardiac arrest compared to adults.

      Introduction

      Risk stratification for the potential of sudden cardiac death in young patients with Wolff-Parkinson-White (WPW) syndrome remains a somewhat controversial and imprecise exercise. Although clinical parameters such as unexplained syncope or a family history of WPW may correlate with increased risk, most commonly the risk is estimated based on parameters observed during episodes of clinical tachycardia or variables measured during electrophysiology study (EPS).
      • Etheridge S.P.
      • Escudero C.A.
      • Blaufox A.D.
      • et al.
      Life-threatening event risk in children with Wolff-Parkinson-White syndrome: a multicenter international study.
      ,
      Pediatric and Congenital Electrophysiology Society (PACES)
      Heart Rhythm Society (HRS), American College of Cardiology Foundation (ACCF), et al. PACES/HRS expert consensus statement on the management of the asymptomatic young patient with a Wolff-Parkinson-White (WPW, ventricular preexcitation) electrocardiographic pattern: developed in partnership between the pediatric and congenital electrophysiology society (PACES) and the Heart Rhythm Society (HRS).
      While variables such as the antegrade accessory pathway effective refractory period or the shortest paced cycle length with pre-excitation during atrial pacing are commonly used, the shortest pre-excited R-R interval (SPERRI) during atrial fibrillation is a generally considered the measurement that best defines the risk of sudden cardiac death, owing to rapid antegrade conduction resulting in ventricular fibrillation.
      • Klein G.J.
      • Bashore T.M.
      • Sellers T.D.
      • Pritchett E.L.
      • Smith W.M.
      • Gallagher J.J.
      Ventricular fibrillation in the Wolff-Parkinson-White syndrome.
      In this report, we describe a patient with a high-risk accessory pathway whose SPERRI significantly shortened during sustained atrial flutter compared to SPERRI measurements in atrial fibrillation or other programmed stimulation parameters. The mechanism for this observation and the implications regarding risk stratification in young patients are discussed.

      Case report

      This case involves a 16-year-old female patient with WPW and episodes of supraventricular tachycardia since the neonatal period. Owing to increasingly frequent and prolonged episodes of supraventricular tachycardia with symptoms including severe chest pain and near-syncope, she was referred for EPS and catheter ablation. Her baseline ECG demonstrated ventricular pre-excitation with a pattern consistent with left anterolateral accessory pathway (Figure 1).
      Figure thumbnail gr1
      Figure 1Baseline electrocardiogram tracing demonstrating ventricular pre-excitation of left anterolateral accessory pathway. The QRS complexes are significantly different from those with maximal pre-excitation in Figures 2 and 3.
      At diagnostic EPS, local ventricular pre-excitation with earliest activation was identified at the distal coronary sinus catheter. Ventricular pacing also demonstrated eccentric and nondecremental ventricular-atrial conduction at the anterolateral aspect of the coronary sinus. The antegrade accessory pathway effective refractory period was 270 ms with 600 ms cycle length drive train. There was persistent antegrade accessory pathway conduction with rapid atrial pacing at 260 ms. Induced orthodromic reciprocating tachycardia converted into atrial fibrillation with a single-interval SPERRI of 228 ms; however, the majority of R-R intervals were in the range of 350–400 ms (Figure 2). Atrial fibrillation then spontaneously converted to atrial flutter with a sustained ventricular cycle length of 195 ms owing to consistent 1:1 A-V accessory pathway conduction with maximally pre-excited QRS complexes (Figures 2 and 3) and loss of demonstrable cardiac output. Atrial flutter terminated spontaneously to normal sinus rhythm during preparation for DC cardioversion. Radiofrequency catheter ablation was then performed with complete elimination of bidirectional accessory pathway connection.
      Figure thumbnail gr2
      Figure 2Surface electrocardiogram tracing of abrupt transition from atrial fibrillation to atrial flutter. Note the somewhat irregular pre-excited QRS complexes with abrupt transition to very rapid, regular, and maximally pre-excited QRS complexes.
      Figure thumbnail gr3
      Figure 3Intracardiac electrograms demonstrating the transition from atrial fibrillation with variable accessory pathway (AP) conduction to atrial flutter and consistent 1:1 AP conduction.

      Discussion

      In patients with WPW, it is generally accepted that the risk of sudden death is related to the characteristics of the accessory pathway(s). The mechanism of sudden death is reported as atrial fibrillation with rapid antegrade accessory pathway conduction leading to ventricular fibrillation.
      • Klein G.J.
      • Bashore T.M.
      • Sellers T.D.
      • Pritchett E.L.
      • Smith W.M.
      • Gallagher J.J.
      Ventricular fibrillation in the Wolff-Parkinson-White syndrome.
      However, this patient demonstrated high-risk accessory pathway characteristics with the SPERRI during atrial fibrillation ≤250 ms in 1 R-R interval only. Conversely, the SPERRI further shortened during atrial flutter with sustained 1:1 AP conduction at a cycle length of 195 ms.
      For adult patients with WPW, high-risk is defined as the SPERRI during atrial fibrillation ≤250 ms, the presence of multiple accessory pathways, an accessory pathway refractory period ≤240 ms, or atrioventricular reentrant tachycardia precipitating pre-excited atrial fibrillation.
      • Page R.L.
      • Joglar J.A.
      • Caldwell M.A.
      • et al.
      2015 ACC/AHA/HRS guideline for the management of adult patients with supraventricular tachycardia: a report of the American College of Cardiology/American Heart Association task force on clinical practice guidelines and the Heart Rhythm Society.
      • Al-Khatib S.M.
      • Arshad A.
      • Balk E.M.
      • et al.
      Risk stratification for arrhythmic events in patients with asymptomatic pre-excitation: a systematic review for the 2015 ACC/AHA/HRS guideline for the management of adult patients with supraventricular tachycardia: a report of the American College of Cardiology/American Heart Association task force on clinical practice guidelines and the Heart Rhythm Society.
      For children, catheter ablation is recommended for those with a SPERRI ≤250 ms, those with structural heart disease for which an arrhythmia may result in poor hemodynamics, or those who have developed ventricular dysfunction.
      Pediatric and Congenital Electrophysiology Society (PACES)
      Heart Rhythm Society (HRS), American College of Cardiology Foundation (ACCF), et al. PACES/HRS expert consensus statement on the management of the asymptomatic young patient with a Wolff-Parkinson-White (WPW, ventricular preexcitation) electrocardiographic pattern: developed in partnership between the pediatric and congenital electrophysiology society (PACES) and the Heart Rhythm Society (HRS).
      However, it has also been reported that patients with life-threatening events may have accessory pathway properties that are not deemed high-risk and low threshold for ablation should be considered.
      • Etheridge S.P.
      • Escudero C.A.
      • Blaufox A.D.
      • et al.
      Life-threatening event risk in children with Wolff-Parkinson-White syndrome: a multicenter international study.
      Atrial flutter and atrial fibrillation are proposed to be related entities and may transform into one another, as demonstrated with our patient.
      • Manolis A.S.
      Contemporary diagnosis and management of atrial flutter: a continuum of atrial fibrillation and vice versa?.
      This was associated with a significant decrease in the pre-excited R-R interval (195 ms) and cardiovascular collapse. The change in the SPERRI is consistent with concealed conduction during atrial fibrillation, resulting in variable prolongation of the accessory pathway refractoriness but with more uniform repolarization during atrial flutter allowing 1:1 conduction.
      • Klein G.J.
      • Yee R.
      • Sharma A.D.
      Concealed conduction in accessory atrioventricular pathways: an important determinant of the expression of arrhythmias in patients with Wolff-Parkinson-White syndrome.
      This raises an important point when patients with WPW are deemed to have low-risk pathways based on EPS testing and the type of atrial arrhythmia (atrial fibrillation vs atrial flutter) that measurements are obtained. The transition of atrial fibrillation to atrial flutter with very rapid sustained conduction may offer a possible explanation for the higher incidence of sudden death in young patients with WPW syndrome compared to older patients.
      • Obeyesekere M.N.
      • Klein G.J.
      Application of the 2015 ACC/AHA/HRS guidelines for risk stratification for sudden death in adult patients with asymptomatic pre-excitation.

      Conclusion

      Invasive risk stratification for pediatric patients with WPW is imperfect. The relationship of atrial fibrillation (with concealed conduction) and atrial flutter (absence of concealed conduction) may offer an explanation for sudden death or life-threatening events in children who have low-risk pathways by invasive electrophysiologic testing. Catheter ablation should be considered at the time of EPS if safe and feasible.

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