@baz10, your question is beyond my knowledge. However, I found this explanation online:
"The main distinguishing feature between LGL and WPW syndromes is that the accessory pathway in LGL syndrome connects distally to the normal conduction pathway (bundle of His), and in WPW the accessory pathway connects to the ventricular myocardium. Thus, both disease states can have a short PR interval, however LGL syndrome will not have a delta wave or widened QRS complex as seen in WPW syndrome. This is because ventricular activation occurs normally in LGL syndrome instead of occurring from myocyte to myocyte as seen in WPW.

Similar arrhythmias occur with LGL syndrome and WPW syndrome, including atrioventricular reentrant tachycardia (AVRT) and rapidly conducting atrial fibrillation. Treatment is similar to WPW and procainamide is frequently utilized. Ablation of the accessory pathway is more difficult in LGL syndrome compared to WPW syndrome since it is located very close to the AV node and there is risk of causing complete heart block necessitating permanent pacemaker implantation." https://www.healio.com/cardiology/learn-the-heart/ecg-review/ecg-topic-reviews-and-criteria/lown-ganong-levine-syndrome-review