OUTCOMES OF EMPIRIC SLOW PATHWAY ABLATION IN DOCUMENTED BUT NON-INDUCIBLE SUPRAVENTRICULAR TACHYCARDIA

Empiric slow pathway ablation (ESPA) is a slow pathway ablation in patients with non-inducible supraventricular tachycardia (SVT) at electrophysiology study (EPS). We earlier documented that the practice of ESPA is common in Canada (5-10% of SVT cases); evidence to support this approach is limited. The aim of this study is to assess efficacy and safety of ESPA in adults. A multi center cohort study of patients who had ESPA between January 2008 and October 2013 was performed. Patients were identified by screening reports of consequent SVT ablation procedures. Forty-three (5%) out of 859 SVT ablation procedures were identified as ESPA. The median age was 53 (IQR: 24) years, 63% were female; none had structural heart disease. All patients had pre-EPS documentation of SVT (either strip or ECG). In 23 (53.5%) cases, pre-EPS ECG convincingly showed short RP tachycardia. Frequency of pre-procedural episodes ranged between daily to quarterly. During diagnostic EPS, none of the patients had inducible SVT or explicit signs of an accessory pathway. Thirty-two (74.4%) patients had DAVNP plus echo beats, 9 (20.9%) patients had DAVNP only, and 2 (4.7%) patients had no DAVNP. Junctional rhythm (JR) as procedural endpoint was noted in 39 (90.7%) patients. In 18 (41.9%) patients, abolishment of DAVNP was achieved. No complications were encountered. A median follow up of 17 months (6 to 31 months) revealed 83.7% (36 of 43) success rate, defined as absence of pre-procedural symptoms and any documented sustained arrhythmia during follow-up. All recurrences (n=7) occurred within 2 months after the procedure. As compared to patients with recurrence (n=7), patients with no recurrence (n=36) had significantly higher prevalence of clinical short RP tachycardia (61.1% vs. 14.3%, p=0.038), and EPS finding of DAVNP plus echo beats (80.6% vs. 42.9%, p=0.034). Groups were similar with respect to other baseline characteristics. In patients with DAVNP, presence of echo beats on EPS was associated with a higher 2-year probability of freedom from recurrence (90.6% vs. 55.6%, Long-rank P=0.023). Absence of DAVNP plus echo beats on EPS was the only predictor of recurrence in Cox proportional hazards model (p=0.048. HR: 4.53 95%CI 1.013 to 20.23). JR alone versus JR plus abolishment of DAVNP as procedural endpoints had no influence on long-term success (p=0.27). ESPA is a reasonable approach in patients with documented SVT, in particular short RP tachycardia, who are not inducible at EPS. Larger studies are required to assess this practice.