Background The diagnostic accuracy of incremental atrial pacing (IP) to determine complete cavo‐tricuspid isthmus (CTI) block during typical atrial flutter (AFL) ablation is limited by both an extensive/nonlinear ablation and/or the presence of intra‐atrial conduction delay elsewhere in the right atrium. We examined the diagnostic performance of an IP variant based on the assessment of the atrial potentials adjacent to the ablation line which aims at overcoming both limitations. Methods From a prospective population of 108 consecutive patients, 15 were excluded due to observation of inconclusive CTI ablation potentials precluding for a straight comparison between the IP maneuver and its variant. In the remaining 93, IP was performed from the low lateral right atrium and the coronary sinus ostium, with the ablation catheter positioned both at the CTI line and adjacent (<5 mm) to its septal and lateral aspect. The IP variant consisted of measuring the interval between the two atrial electrograms situated on the same side of the ablation line, opposite to the pacing site, a ≤10 ms increase indicating complete CTI block. Results The IP maneuver and its variant were consistent with complete CTI block in 82/93 (88%) and 87/93 (93%) patients, respectively. Four patients had AFL recurrence during follow‐up: 2/4 and 4/4 had been adequately classified as incomplete block by the IP maneuver and its variant, respectively. Twenty‐three patients (24%) had significant intra‐atrial conduction delay elsewhere in the right atrium. The IP maneuver and its variant were suggestive of an incomplete CTI block in 11/23 and 4/23 in this setting (P = .028), with the later best predicting subsequent AFL relapses (2/12 vs 2/4, P = .01). Conclusions The IP variant, which was designed to overcome the limitations of the conventional IP maneuver, accurately distinguishes complete from incomplete CTI block and helps to predict AFL recurrences after ablation.

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Background: Pulmonary veins isolation (PVI) is a standard treatment for recurrent atrial fibrillation (AF). Uninterrupted anticoagulation for minimum 3 weeks before the ablation and exclusion of left atrial (LA) thrombus with transesophageal echography (TEE) immediately before or during the procedure minimize peri-procedural risk. We aimed to demonstrate the utility of cardiac tomography (CT) and cardiac magnetic resonance (CMR) to rule out LA thrombus prior to PVI.Methods: Patients undergoing PVI for recurrent AF were retrospectively evaluated. Only patients that started anticoagulation at least 3 weeks prior to the CT/CMR and subsequently uninterrupted until the ablation procedure were selected. An intracardiac echo (ICE) catheter was used in all patients to evaluate LA thrombus. The results of CT/CMR were compared to ICE imaging.Results: We included 272 consecutive patients averaging 54.5 years (71% male; 30% persistent AF). Average CHA2DS2VASC Score was 0.9 and mean LA diameter was 43 mm, 111 patients on Acenocumarol and 161 on direct oral anticoagulants. Anticoagulation was started 227±392 days before the CT/CMR, and 291±416 days before the ablation procedure. CT/CMR diagnosed intracardiac thrombus in 2 cases, both in the LA appendage. A new CT/CMR revealed resolution of thrombus after 6 additional months of uninterrupted anticoagulation. No macroscopic thrombus was observed in any patients with ICE (negative predictive value of 100%; p<0.01).Conclusions: CT and MRI are excellent surrogates to TEE and ICE to rule out intracardiac thrombus in patients adequately anticoagulated prior AF ablation. This is true even for delayed procedures as long as anticoagulation is uninterrupted.

Purpose: Patients undergoing cavotricuspid isthmus (CTI) ablation for typical flutter (AFL) have a high incidence of new onset atrial fibrillation (AF). We aimed to analyze the incidence and predictors for new onset AF in this subset of patients to stratify thromboembolic risk. Methods: Between 2016 and 2019, 70 patients without history of AF but with high-risk for developing AF, based on a recent AFL ablation or a high PACE score for AF risk, were prospectively included. All patients were monitored continuously by implantable loop recorder and followed by remote monitoring.Results: Overall 48 patients were included after CTI ablation and 22 patients were included based on a high PACE score. New onset AF rate at 12 months was significantly higher in the AFL group compared to PACE group (56.3% vs 22.7%, p=0.011). History of AFL was the only independent predictor for new onset AF (HR:3.82; 95% CI:1.46-10.03; p=0.006) at a median follow-up of 12 months (Q1-Q3:4-19 months). In the AFL group, two very strong independent predictors for new onset AF were a PACE score ³30 (HR:6.9; 95% CI:1.71-27.91; p=0.007) and HV interval ³55 (HR:11.86; 95% CI:2.57-54.8; p=0.002).Conclusions: AFL is the most important predictor for new onset AF. In patients undergoing AFL ablation, a high PACE score and/or long HV interval predict even higher risk, and may be useful in decision for empiric long-term anticoagulation.