20 years of natural history and electrophysiological follow-up of WPW syndrome with transesophageal pacing

The reported incidence of sudden death (SD) in Wolff-Parkinson-White (WPW) syndrome ranges between 0 and 0.15% per year. Our perspective follow-up (F-up) study aimed to assess the prognostic value of transesophageal electrophysiology testing (TEEPT) for risk assessment, in a large cohort of WPW patients (pts). METHODS: 212 WPW pts (162 male, 50 female, mean age 35.3±14), 75 with palpitations, were followed between 1986 and 2006. TEEPT was performed at entry in 196 (143 with stable and 53 unstable ventricular preexcitation), at rest and under effort. A second TEEPT was carried out in 124 pts within 6 months. The overall F-up TEEPT were 672. Atrio-Ventricular (AV) Node and Kent (K) antegrade effective refractory periods (ERP) at pacing cycle lengths (PCL) 600, 400 and 320 ms, inducibility of AV-reentry tachycardia (AVRT), of atrial fibrillation (AF) and shortest preexcited RR interval during sustained AF (SRRaf) and/or atrial pacing (SRRp) were assessed. RESULTS: Mean F-up was 10.8±5.9 years (total 2278 patient-years). KERP and SRRaf varied as a function of posture, PCL and adrenergic tone. Mean KERP was 260 msec (range 237-300) at rest and 219 msec (209-229) under effort. Mean SRRaf interval was 268±68 msec (160-400) at rest and 200±48 msec (160-325) under effort. SRRp was 265±23 msec (220-310) at rest, 223±33.6 msec (160-310) under effort. AVRT was inducibile in 88 pts at rest and in 96 under effort. SRRfa was <240 msec at rest in 13 pts, <200 msec under effort in 16 pts. AF was inducible in 68 pts at rest and in 85 pts under effort. 14 pts had a SRRaf <190 ms; 2 of them (both with SRRaf <180 msec, at rest) died suddenly (at rest), being ablation refused. 55 pts were placed on drugs after first TEEPT (35 of them underwent ablation, failed in 4). TEEPT was reproducible in untreated pts. CONCLUSIONS: WPW pts have a good medium-term prognosis. The observed mortality (0.08% per year of F-up), although within the average reported in previous natural history studies, could be avoided, having both pts been identified as mandatory candidates to ablation on the basis of TEEPT results. SRRaf interval shorter than 180 msec at rest, associated with symptomatic spontaneous and inducible antidromic AVRT and AF, were markers suggestive for risk of SD, conferming the findings of Torner-Montoya. However both SDs occurred at rest, one during a pyretic episode. Thus "silent pathology", such as subclinical myocarditis, or conditions implying sudden unbalancement of cardiac autonomic drive have to be taken into account as possible concauses that might enhance the risk of ventricular electrical instability