134A ABSTRACTS-Cardiac Arrhythmias JACC 1212-18 Identification of Endocardial Trigger and Exit of Right Ventricular Outflow Tract Tachycardia: Implication for Radiofrequency Catheter Ablation

Background: Catecholamine sensitive triggered activity seems to be the mechanism of idiopathic right ventricular outflow tract tachycardta (RVOT VT) and early after depolarization is associated with the occurrence of this type of VT. We investigated whether the endocardial triggers during diastolic period precede the exit of RVOT VT and can be identified by non-contact mapping system (ES 3000) to guide successful radiofrequency (RF) catheter ablation (RFCA). Methods: The study included 11 patients with RVOT VT referred for non-contact mapping and RFCA (4 women, 44+7 years, range 22 to 55). No patients had structural heart diseases es documented by normal echocardrography and cardiac magnetic resonance imaging. All patients had an inferiorly directed VT configuration, with a precotdial R wave transition equal to or later than V3. VTs were induced by rapid ventricular pacing and/or after isopmterenol infusion. The multielectrode array was positioned at the RVOT to identity endocardial triggers preceding the exit points of VT. RF was applied at the exits or the area between exit and trigger. Results: The earliest endocardral exits were registered at RVOT -27+9 ms before onset of QRS in all patients. The earlrest diastolic triggers were identified within the distance of 28t.15 mm from the exits and registered -71*28 ms before QRS in 8/l 1 patients. A line of block between exits and triggers was made in 8 patrents and targeted the exits in 3 patients. At a follow-up of 7& months, recurrence was noted only in exit-targeted patients (2J3, vs. none in those with successful linear block). Conclusions: The endocardial trigger and exit points could be Identified in most patients with RVOT VT using non-contact mapping system and are useful to gurde effective RFCA. made on admtssion at the bedside using a ap top computer. Standard time and frea, quency domain measures were calculated ( can NN mterval, SDNN, rMSSD, pNN50, LF, HF and total power). Notification of death was obtained through the UK Office for National Statistics, with 100% follow-up censored at 18 months from the end of recruitment. The primary outcome measure was the survival of those subjects having HRV values in the lowest quartile versus those with higher HRV values. Results 164 subjects were approached for inclusion. HRV data was completed in 135. 21 patients died durmg follow-up, all from cardiovascular causes (median 9, range O-24 months post-MI). Baseline characteristics were: age (63 + 12); male sex (70%); diabetes (8%); hypertension (33%); smoking (47%); cholesterol (5.8 + 1.2 mmol/L); BMI 26 -f 4; family history (26%). Ml characteristics were: inferior (51%); anterior (45%); LBBBl hot classified (4%); peak CK 1944 -+ 1529 u/L; post-MI LVEF 50 + 15%. Using the log rank test, reduction in 3 HRV parameters was associated with an adverse outcome: mean RR (median 836 ms, 25% centile ~723 ms, hazard retro 3.75 (95% Cl 128 10.95) p=O.O02): SDNN (22, cl4 ms, hazard ratio 3.05 (95% Cl 1.04 -8.92) p=O.Ol I); and total power (491, ~203 ms s, hazard ratio 2.82 (95% Cl 0.92 8.58) p=O.O26). Conclusion: Reduced HRV assessed post-MI using short-term 5 minute recordings is significantly associated with an adverse prognosis due to cardiovascular death.