Background-Catheter ablation of ventricular tachycardia (VT) is effective and particularly useful in patients with frequent defibrillator interventions. Various substrate modification techniques have been described for unmappable or hemodynamically intolerable VT. Noninducibility is the most frequently used end point but is associated with significant limitations, so the optimal end point remains unclear. We hypothesized that elimination of local abnormal ventricular activities (LAVAs) during sinus rhythm or ventricular pacing would be a useful and effective end point for substrate-based VT ablation. As an adjunct to this strategy, we used a new high-density mapping catheter and frequently used epicardial mapping. Methods and Results-Seventy patients (age, 67Ϯ11 years; 7 female) with VT and structurally abnormal ventricle(s) were prospectively enrolled. Conventional mapping was performed in sinus rhythm in all, and a high-density Pentaray mapping catheter was used in the endocardium (nϭ35)

Atrial fibrosis as defined by DE MRI is associated with slower and more organized electrical activity but with lower voltage than healthy atrial areas. Ninety percent of continuous CFAE sites occur at non-DE and patchy DE LA sites. These findings are important when choosing the ablation strategy in persistent AF.

No abstract

Background: Atrial fibrillation (AF) and heart failure (HF) frequently coexist and can be challenging to treat. Pharmacologic based rhythm-control of AF has not proven to be superior to rate-control. Ablation-based rhythm-control was compared to rate-control to evaluate if clinical outcomes in patients with HF and AF could be improved. Methods: This was a multicenter, open-label trial with blinded outcome evaluation using a central adjudication committee. Patients with high burden paroxysmal (>4 episodes in six months) or persistent (duration < three years) AF, New York Heart Association class II-III HF, and elevated NT-proBNP were randomized to ablation-based rhythm-control or rate-control. The primary outcome was a composite of all-cause mortality and all HF events, with a minimum follow up of two years. Secondary outcomes included left ventricular ejection fraction (LVEF), six-minute walk test and NT-proBNP. Quality of life was measured using the Minnesota Living with Heart Failure Questionnaire (MLHFQ) and the AF Effect on quality of life (AFEQT). The primary analysis was time-to-event using Cox proportional hazards modeling. The trial was stopped early due to a determination of apparent futility by the Data Safety Monitoring Committee. Results: From December 1, 2011, to January 20, 2018, 411 patients were randomized to ablation-based rhythm-control (n=214) or rate-control (n=197). The primary outcome occurred in 50 (23.4%) patients in the ablation-based rhythm-control group and 64 (32.5%) patients in the rate-control group (hazard ratio 0.71 95% CI (0.49, 1.03), p=0.066). LVEF increased in the ablation-based group (10.1±1.2% vs 3.8±1.2%, p=0.017); six-minute walk distance improved (44.9±9.1 meters 27.5±9.7 meters, p=0.025) and NT-proBNP demonstrated a decrease (mean change -77.1% vs -39.2%, p<0.0001). MLHFQ demonstrated greater improvement in the ablation-based rhythm-control group (LSMD of -5.4, 95%CI (-10.5, -0.3), p=0.0036), as did the AFEQT score (LSMD of 6.2, 95%CI (1.7, 10.7), p=0.0005). Serious adverse events were observed in 50% of patients in both treatment groups. Conclusions: In patients with high burden AF and HF, there was no statistical difference in all-cause mortality or HF events with ablation-based rhythm-control versus rate-control, however, there was a non-significant trend for improved outcomes with ablation-based rhythm control over rate-control.

Background Complex fractionated electrograms (CFAE) are targets of atrial fibrillation (AF) ablation. Serial high density maps were evaluated to understand the impact of activation direction and rate on electrogram (EGM) fractionation. Methods and Results 18 patients (9 persistent) underwent high density, 3D, left atrial mapping (>400 points/map) during AF, Sinus (SR) and CS-paced (CSp) rhythms. In SR and CSp, fractionation was defined as EGM with ≥4 deflections, while in AF CFEmean <80ms was considered as continuous CFAE. The anatomic distribution of CFAE sites was assessed, quantified and correlated between rhythms. Mechanisms underlying fractionation were investigated by analysis of voltage, activation and propagation maps. A minority of continuous CFAE sites displayed EGM fractionation in SR (15+/−4%) and CSp (12+/(12+/−8%). EGM fractionation did not match between SR and CSp at 70+/−10% sites. Activation maps in SR and CSp showed that wave collision (71%) and regional slow conduction (24%) caused EGM fractionation. EGM voltage during AF (0.59+/−0.58mV) was lower than during SR and CSp (>1.0mV) at all sites. During AF, the EGM voltage was higher at continuous CFAE sites than at non-CFAE sites (0.53mV (Q1, Q3: 0.33–0.83) vs. 0.30 mV (Q1, Q3: 0.18–0.515), p<0.00001). Global LA voltage in AF was lower in persistent vs. paroxysmal AF patients (0.6+/−0.59mV vs. 1.12+/−1.32mV, p<0.01). Conclusions The distribution of fractionated EGMs is highly variable, depending on direction and rate of activation (SR vs. CSp vs. AF). Fractionation in sinus and CSp rhythms mostly resulted from wave collision. All sites with continuous fractionation in AF displayed normal voltage in SR suggesting absence of structural scar. Thus, many fractionated EGMs are functional in nature and their sites dynamic.

No abstract

Background-Patients who receive implantable cardioverter defibrillator therapies are at higher risk of death versus those who do not. Programmed settings to reduce nonessential implantable cardioverter defibrillator therapies (therapy reduction programming) have been developed but may have adverse effects. This systematic review and meta-analysis assessed the relationship between therapy reduction programming with the risks of death from any cause, implantable cardioverter defibrillator shocks, and syncope. Methods and Results-MEDLINE, EMBASE, and clinicaltrials.gov databases were searched to identify relevant studies.Those that followed patients for ≥6 months and reported mortality were included. Most (77%) participants were men, had a history of ischemic heart disease (56%), and were prescribed β-blockers (84%). Therapy reduction programming was associated with a 30% relative reduction in mortality (95% confidence interval, 16%-41%; P<0.001). No significant heterogeneity among studies was observed (P=0.6). A similar 26% reduction in mortality was observed when only the 4 randomized trials were included (95% confidence interval, 11%-40%; P=0.002). These results were not significantly altered after adjustment for baseline characteristics. No significant difference in the risk of syncope was observed with conventional versus therapy reduction programming (P=0.5). Conclusions-Therapy reduction programming results in a large, significant, and consistent reduction in mortality, with no apparent increase in the risk of syncope. (Circ Arrhythm Electrophysiol. 2014;7:164-170.)

This prospective multicenter series shows a high success rate of ECM in accurately diagnosing the mechanism of AT and the location of focal arrhythmia. Intraprocedural use of the system and its application to atrial fibrillation mapping is under way.