CHD Electrophysiology Featured Articles of June 2015

1. Clinical and electrophysiological evaluation of pediatric Wolff-Parkinson-White patients.

Yıldırım I, Özer S, Karagöz T, Şahin M, Özkutlu S, Alehan D, Çeliker A.

Anatol J Cardiol. 2015 Jun;15(6):485-90. doi: 10.5152/akd.2014.5462. Epub 2014 Jun 23.

PMID: 26006136 Free Article

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Select item 25820181

cohen picComment from Dr. Mitchell Cohen (Phoenix), section editor of Congenital Heart Electrophysiology Journal Watch: Drs. Yildrim and colleagues from Turkey have written an excellent retrospective review of their experience with risk stratification in children with ventricular preexcitation. Over the course of nearly 15 years they reviewed their experience in 109 patients who underwent an initial transesophageal EPS as part of risk stratification. The currently published guidelines from the Pediatric & Congenital EP Society (PACES) in conjunction with the Heart Rhythm Society (Cohen MI et al. Heart Rhythm 2012 Jun;9(6):1006-24) have recommended that initial risk stratification be pursued with an exercise stress test (children > 8 years of age) and in the absence of clear and abrupt loss of preexcitation on the treadmill an invasive EPS be performed next. The 2012 guidelines only apply to patients who are asymptomatic and do not necessarily extend to symptomatic patients.

109 patients with WPW were identified with the initial symptom of tachycardia in 82, syncope in 14, and 13 patients were asymptomatic.

  • Of the 82 tachycardia patients: atrial fibrillation was induced in 6 patients (7.3%) with all having an APERP < 250 msec and < 220 msec in 3 of theses 6 patients.
  • Of the 14 patients with syncope: atrial fibrillation was induced with 5 (36%) and 1 of these degenerated to ventricular fibrillation. The APERP value was < 270 msec (1 patient), < 250 msec (6 patients), < 220 msec (7 patients). The APERP value of the patient whose atrial fibrillation degenerated to ventricular fibrillation was 180 msec.
  • Of the 13 asymptomatic patients: SVT was induced in 7 patients, atrial fibrillation in 1 patient, which degenerated to ventricular fibrillation (APERP < 180 msec). In the 7 patients with inducible SVT all had an APERP < 250 msec and of the 6 asymptomatic patients without inducible SVT or atrial fibrillation 3 had an APERP < 250 msec.

For the most part, the data that is presented is consistent with many previously published series. For starters patients with WPW who have had syncope are likely to have a rapidly conducting accessory pathway and should be considered for an EP study and catheter ablation. This data is consistent with earlier work published from Drs. Paul and Gillette from Texas Childrens in the 1990s. This study found that even amongst asymptomatic patients, those patients might harbor a rapidly conducting accessory pathway and appropriately recommend risk stratification. The finding that asymptomatic patients may have inducible SVT is not uncommon and coincided with the data presented. The fact that one of the 13 asymptomatic patients actually had inducible atrial fibrillation, which degenerated to ventricular fibrillation, is unusual but has been previously documented. It is for this patient that risk stratification in the asymptomatic patient is critical.

The manner in which risk stratification should be performed has varied between an initial non-invasive risk stratification (exercise stress testing) and invasive risk stratification. In this article the authors recommended that transesophageal EP testing be used as initial risk stratification. The authors argued in their discussion that there are technical difficulties in performing exercise stress testing in upwards of 20% of children. Esophageal EP testing has many additional features compared to an exercise stress test. Esophageal EP testing allows for the ability to assess the minimal cycle length of preexcitation, APERP, and the potential for SVT inducibility. Generally the data measured with esophageal EP testing correlates with invasive EP testing. However, esophageal EP testing still may require some level of sedation and the expense of the cath lab personnel and lab time. The clear and abrupt loss of the delta wave on the stress test has been shown to correlate very well with having a non-rapid accessory pathway. (Wackel P,PACE 2012 Dec 35(12): 1451-7).  When all is said and done, exercise testing still seems to be an excellent noninvasive tool to identify patients not at risk for a rapidly conducting accessory pathway but only about 15-18% of patients truly show that on an exercise stress test and the vast majority will need further invasive EP testing. The decision to start with either an exercise stress test or an esophageal EP study is reasonable. Which action is taken probably depends more on the resources available and the program itself. In the end, it is important that asymptomatic patients, as shown in this paper, are evaluated in some way. If esophageal EP testing is chosen, that is a reasonable course for some institutions. On the other hand, noninvasive testing with a stress test is also reasonable as long as one carefully scrutinizes the tracings to be certain that there is a clear and abrupt loss of the delta wave and not augmented nodal conduction obscuring manifest preexcitation.

Take Home Points: Clinical and electrophysiological evaluation of pediatric Wolff-Parkinson-White patients.

  1. Patients with syncope and WPW should be evaluated with some form of an invasive EP test as >90% will have an APERP < 250 msec.
  2. Asymptomatic patients with ventricular pre-excitation may harbor a potentially rapid conducting accessory pathway.
  3. Risk stratification should be considered in asymptomatic patients with ventricular preexcitation.
  4. Risk stratification may be instituted with a trans-esophageal EP study. This allows minimal sedation and can assess for the antegrade characteristics of the accessory pathway, the APERP, and whether there is inducible reentrant SVT. This study did not compare exercise tests with trans-esophageal EP testing.

 

2. Premature ventricular contraction-induced cardiomyopathy in children.

Spector ZZ, Seslar SP.

Cardiol Young. 2015 Jun 17:1-7. [Epub ahead of print]

PMID: 26082146

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Select item 26085007

Comment from Dr. Mitchell Cohen (Phoenix), section editor of Congenital Heart Electrophysiology Journal Watch:  Premature ventricular beats in children with a structurally normal heart in the absence of a family history of sudden cardiac death or a family history of a cardiomyopathy are often considered a benign condition. However the question that often arises is, “how much ventricular ectopy is too much?” In adults, there is growing evidence that patients with what were once felt to have benign frequent PVCs now under more non-invasive scrutiny develop LV systolic dysfunction, diastolic dysfunction, LV dilation, or ventricular strain by speckle-imaging. Spector and Seslar from Seattle Children’s Hospital performed a retrospective review of 36 patients between 1990-2013 who had >20% ventricular ectopy with a structurally normal heart. Of these 7 actually presented with a cardiomyopathy. This is one of the limitations of the paper as these patients were not followed with “benign PVCs” and progressed to a cardiomyopathic picture. However, in looking at these 7 patients 6 had LBBB, inferior axis consistent with an RVOT origin and 4/7 had diminution of PVCs at higher heart rates, a phenomenon that we have typically associated with a benign form of ectopy. PVCs resolved in about 16% of patients, but upwards of 50% continued to have a significant ventricular ectopy burden at 21 years of age. There was little demographic data that was predictive of a high ectopy burden. Given the small numbers of patients followed late on the Kaplan-Meir curve a larger series of patients will need to be followed. This study was not powered to address either ant-arrhythmic suppression or the benefits and timing of when a catheter ablation should be performed.

Take Home Points: Premature ventricular contraction-induced cardiomyopathy in children.

  1. Children with frequent PVCs (>20%) with a LBBB, inferior axis (RVOT origin) and suppression on an exercise stress test may be a risk for developing a cardiomyopathy.
  2. The exact number of PVCs, location of ectopy origin, and the duration of having an ectopy burden >20% that might cause ventricular dysfunction, LV dilation, or LV diastolic dysfunction remains unknown.
  3. This study should open the door for a future prospective study in children with a structurally normal heart and frequent PVCs.
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