Artificial intelligence software standardizes electrogram-based ablation outcome for persistent atrial fibrillation.

INTRODUCTION: Multiple groups have reported on the usefulness of ablating in atrial regions exhibiting abnormal electrograms during atrial fibrillation (AF). Still, previous studies have suggested that ablation outcomes are highly operator- and center-dependent. This study sought to evaluate a novel machine learning software algorithm named VX1 (Volta Medical), trained to adjudicate multipolar electrogram dispersion. METHODS: This study was a prospective, multicentric, nonrandomized study conducted to assess the feasibility of generating VX1 dispersion maps. In 85 patients, 8 centers, and 17 operators, we compared the acute and long-term outcomes after ablation in regions exhibiting dispersion between primary and satellite centers. We also compared outcomes to a control group in which dispersion-guided ablation was performed visually by trained operators. RESULTS: The study population included 29% of long-standing persistent AF. AF termination occurred in 92% and 83% of the patients in primary and satellite centers, respectively, p = 0.31. The average rate of freedom from documented AF, with or without antiarrhythmic drugs (AADs), was 86% after a single procedure, and 89% after an average of 1.3 procedures per patient (p = 0.4). The rate of freedom from any documented atrial arrhythmia, with or without AADs, was 54% and 73% after a single or an average of 1.3 procedures per patient, respectively (p < 0.001). No statistically significant differences between outcomes of the primary versus satellite centers were observed for one (p = 0.8) or multiple procedures (p = 0.4), or between outcomes of the entire study population versus the control group (p > 0.2). Interestingly, intraprocedural AF termination and type of recurrent arrhythmia (i.e., AF vs. AT) appear to be predictors of the subsequent clinical course. CONCLUSION: VX1, an expertise-based artificial intelligence software solution, allowed for robust center-to-center standardization of acute and long-term ablation outcomes after electrogram-based ablation.

Electrogram Fractionation-Guided Ablation in the Left Atrium Decreases the Frequency of Activation in the Pulmonary Veins and Leads to Atrial Fibrillation Termination: Pulmonary Vein Modulation Rather Than Isolation.

OBJECTIVES: This study sought to evaluate the impact of a complex fractionated atrial electrogram (CFAE)-guided ablation strategy on atrial fibrillation (AF) dynamics in patients with persistent AF. BACKGROUND: It is still unclear whether complete pulmonary vein isolation (PVI) is required or if the ablation of well-delineated pulmonary vein (PV) subregions could achieve similar outcomes in persistent AF. METHODS: CFAE-guided ablations were performed in 76 patients (65.2 ± 10 years of age) with persistent AF. In 47 patients, we measured mean PVs and left atrial appendage (LAA) cycle length (CL) values (PV-CL and LAA-CL), before ablation and before AF termination. We defined "active" PVs as PV-CL ≤ LAA-CL, "rapid fires" as PV-CL ≤80% of LAA-CL, and "PV-LAA CL gradient" as a significant CL difference between the 2 regions. RESULTS: AF termination (sinus rhythm [SR] or atrial tachycardia [AT] conversion) occurred in 92% and SR conversion in 75%. The radiofrequency time for AF termination and total radiofrequency time were 26 ± 25 min and 61.1 ± 21.6 min, respectively. Thirty of 47 patients had active PV (with 19 PV "rapid fires"). Ablation significantly increased median CL, both at PVs and LAA from 188 ms (interquartile range [IQR]: 161 to 210 ms) to 227.5 ms (IQR: 200 to 256 ms) (p < 0.0001) and from 197 ms (IQR: 168 to 220 ms) to 224 ms (IQR: 193 to 250 ms) (p < 0001), respectively. After ablation, PV-LAA CL gradients were withdrawn and all PV "rapid fires" were extinguished (without PVI). After 17.2 ± 10 months of follow-up and 1.61 ± 0.75 procedures, 86.3% and 73% of the patients were free from AF and from any arrhythmia (AF/AT), respectively. CONCLUSIONS: CFAE-guided ablation leads to a large decrease in PV frequency of activation, preceding AF termination. A PV modulation approach, rather than complete PVI, may be preferable for persistent AF.

Active or passive pulmonary vein in atrial fibrillation: is pulmonary vein isolation always essential?

BACKGROUND: The role of pulmonary veins (PVs) in persistent atrial fibrillation (AF) perpetuation appears less important than in paroxysmal AF. Electrogram-based substrate ablation is not widely performed as a stand-alone strategy. OBJECTIVE: To evaluate PV activity in AF perpetuation and efficacy of our patient-tailored ablation strategy (electrogram-based substrate ablation with or without pulmonary vein isolation [PVI]). METHODS: One hundred twenty-one patients with paroxysmal (n = 19; 15.7%), persistent (n = 77; 63.6%), or long-standing persistent (n = 25; 20.7%) AF underwent electrogram-based substrate ablation with AF termination end point: sinus rhythm or atrial tachycardia conversion. Before ablation, we classified PVs as "passive" if silent PV or if PV cycle length is greater than left atrial appendage cycle length. No PVI was performed in such cases. RESULTS: Passive PVs were observed in 52 of 121 patients (paroxysmal AF = 0%, persistent AF = 40%, and long-standing persistent AF = 76%; P < .0001]). Substrate ablation terminated AF in 95.6% (sinus rhythm conversion in 80.2%). Compared with patients with active PVs, patients with passive PVs had longer AF sustained duration (19.1 ± 29.7 months vs 4.9 ± 11.1 months; P < .0001), larger left atrial diameter (46.9 ± 7.3 mm vs 41.9 ± 6.0 mm; P = .0014), lower left ventricular ejection fraction (45.4% ± 13.5% vs 55.1% ± 9.4%; P < .0001), and more often structural heart disease (57% vs 33%; P = .02). After a follow-up of 20.39 ± 11.23 months (1.6 procedures per patient), 82% were arrhythmia free with this strategy. CONCLUSIONS: PV activity during AF decreases with AF chronicity, left atrial dilatation, and left ventricular ejection fraction. Our patient-tailored ablation strategy without systematic PVI provides good results.

Ablation of post-myocardial infarction focal ventricular tachycardia.

In the chronic phase of myocardial infarction, the presence of scar areas allows the development of macro-reentries which become the most frequent mechanism underlying ventricular tachycardia (VT). A focal mechanism has been already described in the presence of scar in animal models or in humans but only during surgery. We report a case of focal automatic VT arising from postinfarction scar fibrosis, successfully mapped and ablated during an electro-physiological procedure.

Robotic magnetic navigation for ablation of human arrhythmias: initial experience.

BACKGROUND: Magnetic navigation system (MNS) (Niobe, Stereotaxis, Saint-Louis, Missouri, USA) allows remote control of a radiofrequency ablation catheter using a steerable magnetic field and a catheter advancement system. AIMS: We report our initial experience of ablation of human arrhythmias using the MNS. METHODS: Eighty-four patients (mean age 54+/-17years; 39 women) had an electrophysiologic study followed by ablation with the MNS using non-irrigated 4, 8 and 3.5mm-tip catheters with three distal magnets. All patients were symptomatic, with commonly-accepted indications for ablation: atrioventricular nodal re-entrant tachycardia (AVNRT; n=37); typical atrial flutter (n=15); accessory pathway (n=12); atypical atrial flutter (n=7); ventricular tachycardia (n=7); atrial tachycardia (n=3); paroxysmal atrial fibrillation (n=3). Electroanatomical mapping was used for atrial flutter, atrial fibrillation, atrial tachycardia and ventricular tachycardia procedures (29 patients, 34%). RESULTS: Ablation was performed successfully in 69 (82%) patients. In 15 patients (18%), MNS technique was unsuccessful: seven typical atrial flutters, four accessory pathways, two left atrial flutters after atrial fibrillation ablation, one ventricular tachycardia and one AVNRT; in all these cases except one typical atrial flutter and two left atrial flutters, success was obtained by switching to the manual technique by means of an irrigated catheter. Total fluoroscopy time was 14+/-11minutes; operator exposure fluoroscopy time was 1.5+/-0.6minutes; procedure time was 169+/-72minutes. CONCLUSION: MNS ablation is a feasible treatment for various human arrhythmias, with a high success rate. Mapping with a magnetic catheter is safe. However, magnetic ablation of typical atrial flutter remains challenging, probably because of insufficient pressure for cavotricuspid isthmus ablation.

Remote implantable cardioverter defibrillator monitoring in a Brugada syndrome population.

AIMS: The diagnosis of Brugada syndrome (BS) is typically made in a young and otherwise healthy population. In patients with a high risk of sudden cardiac death (SCD), the only currently recommended therapy is an implantable cardioverter defibrillator (ICD), but these are not without complications. We investigated whether remote ICD monitoring could simplify follow-up and detect potential complications in these patients. METHODS AND RESULTS: Thirty-five consecutive patients (26 males, 44 +/- 11 years) implanted with an ICD for BS with a remote monitoring ['Home Monitoring' (HM), Biotronik, Germany] system were prospectively enrolled in this study. They were matched for age, sex, and follow-up duration with 35 BS patients implanted with an ICD without this capability. During a mean follow-up of 33 +/- 17 months, the number of cardiology consultations was significantly lower in the HM group (3 +/- 2 vs. 7 +/- 3; P < 0.001). Inappropriate shock(s) [IS(s)] occurred in three patients (8.5%) in the HM group vs. six (17%) in the control group (P = NS). Ten patients in the HM group had a median of four alerts ('ventricular tachycardia/ventricular fibrillation detection' in all patients, 'shock' in three, 'ineffective shock' in two patients with shock on noise, 'extreme ventricular pacing impedance' in one patient due to lead failure, and 'deactivated therapy' in two patients with lead failure before replacement). In 5 of these 10 patients, prompt reprogramming of the ICD may have prevented IS(s). CONCLUSION: Remote ICD monitoring in patients with BS decreases outpatient consultations and may help prevent ISs.