RESULTS
Procedural data
The average procedural time was 213 ± 60.9 min, and an average radiation dose of 5862,5 mGy. Baseline pre-ablation HR was 100 ± 8.5 bpm, and HR at the maximal tolerated dose of Isoproterenol before RFA was 170 ± 19 bpm. Following RFA, average HR was 74.5 ± 6.5 bpm (p=0.035), and maximal HR with the same pre-ablation Isoproterenol doses was 132 ± 23 bpm (p=0.036). Average HR during 24 h Holter pre was 93.16 ± 7.08 and post RFA 76.66 ± 4.92 (p=0.031).
The area of earliest activation was located at the AR (11 or 12 O’clock landmark from a caudal view of the SVC-RA junction) in all patients. Extension of the RF lesions from the earliest region at the AR towards its more septal region was needed in all the included patients and produced a transitory HR increment before obtaining a significant and sustained HR drop of around 25%. Notably, the activation recorded on the septal aspect of the AR was later compared with the earliest site from its lateral aspect. The mean distance between the RF applications at the earliest region on the AR and the most septal ablated sites was 6 mm (Fig 4 d,e). The distance of the PN to the nearest RF application was 5mm (Fig 4 d,e).
Clinical outcomes
After a mean follow-up of 654 ± 417 days (Table 1), one patient required reinitiating Ivabradine (at a lower dose than pre-ablation) for control of symptoms, and one patient with a history of fibromyalgia complained of mild exercise intolerance, despite no evidence of sinus node dysfunction on post-ablation stress test and heart rhythm monitoring. No patients reported heart palpitations or syncope during follow-up. The average HR on 24-hour Holter post-ablation was 75 ± 5.6 bpm, the sinus rate HR during stage 1 of a Bruce protocol exercise stress test was 120 ± 10 bpm, and the chronotropic response was classified as normal by an independent cardiologist in all the patients. (Table 1).