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SVT chance of sudden cardiac death

Sorry for my bad english. So we have a svt patient with normal ecg and echo with suspected episodes of svt. What im intested in is the chance of having accesory pathway capable of antero grade conduction despite the absence of pre excitation in sinus rhythm. Accesory patways that are only capable of retrograde conduction arent dangerous because they lack anterograde conduction which is the key element of atrial fibrillation degenerating to venticular fibrillation. So what im intested are the hidden accesory pathways that are capable of anterograde conduction. And what is the chance of having one when the ecg was normal. First study to help with this http://www.ajconline.org/article/0002-9149(90)91428-9/abstract 22 patients documented svt normal ecg. 6 had a latent accesory pathway. So 6/22. The chance of having latent accesory pathway is around 1/4. This study was done for small population so its not that reliable and the test was done to patients with documented svt and propably suspected mechanism was avrt so this study wasnt reliable. Next one http://www.ncbi.nlm.nih.gov/pubmed/23609066?log$=activity 140 pateints with svt and normal ecg. Accesory pathway capable of anterograde conduction was found in 19 (13,5%). 5 had a rapid conducting accesory pathway. If the life time risk of wpw is 3-4% and the chance of havinc it is 13,5% the overall chance of dying due to atrial fibrillation degenerating into venticular fibrillation is 0.4-0.54% per life time. Any thoughts guys???
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1124887 tn?1313754891
The risk of sudden death with SVT and a normal heart (with normal heart I mean no structural heart disease and normal coronary arteries) is related to the WPW syndrome (accessory pathway between atria and ventricles) in combination with atrial fibrillation. The combination may be dangerous as atrial fibrillation (or flutter) can be conducted through the accessory pathway, causing a very rapid heart rhythm (300 bpm or more).

SVT itself is very rarely dangerous.

It's correct that some people may have "hidden" WPW (no preexcitation on EKG) with a pathway that may conduct impulses backwards. If so, PVCs are often the trigger of SVT rather than PACs. I don't know if such a pathway would be able to conduct impulses from atrial fibrillation?

Anyway, chance of sudden desth with SVT is very rare. But it may be a good idea to find out which SVT you have, and possibly get it treated? There are common variants of SVT which don't involve accessory pathways and where atrial fibrillation is no more dangerous than it would be without SVT.
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