Background-The high incidence of postprocedural atrial tachycardia reduces the absolute arrhythmia-free success rate of extensive ablation strategies to treat nonparoxysmal atrial fibrillation (NPAF). We hypothesized that a strategy of targeting low-voltage zones and sites with abnormal electrograms during sinus rhythm (SR-AEs) in the left atrium after circumferential pulmonary vein isolation and cavotricuspid isthmus ablation in patients with NPAF is superior. Methods and Results-A total of 86 consecutive patients with NPAF were enrolled in study group. After circumferential pulmonary vein isolation, cavotricuspid isthmus ablation and cardioversion to SR, high-density mapping of left atrium was performed. Areas with low-voltage zone and SR-AE were targeted for further homogenization and elimination, respectively; 78 consecutive sex-and age-matched patients with NPAF who were treated with the stepwise approach served as the historical control group. In the study group, 92% (79/86) were successfully cardioverted after circumferential pulmonary vein isolation and cavotricuspid isthmus ablation. Among the patients converted to SR, 70% (55/79) had lowvoltage zone and SR-AE and received additional ablation, whereas in 30% (24/79) without SR-AE or low-voltage zone, no further ablation was performed. During a follow-up period of >30 months, the Kaplan-Meier estimated probability to maintain SR at 24 months was 69.8% versus 51.3%. And after a single procedure, 3.5% (3/86) developed postprocedural atrial tachycardia in study group, compared with 30% (24/78) in control group (P=0.0003). Conclusions-A strategy of selective electrophysiologically guided atrial substrate modification in SR after circumferential pulmonary vein isolation and cavotricuspid isthmus ablation is clinically more effective than the stepwise approach for NPAF ablation. Clinical Trial Registration-URL: http://clinicaltrials.gov. Unique identifier: NCT01716143.(Circ Arrhythm Electrophysiol. 2016;9:e003382.

BackgroundLeft bundle branch area pacing (LBBAP) was reported to improve cardiac function by correcting complete left bundle branch block (CLBBB). Our study aimed to compare the efficacy of LBBAP and biventricular pacing (BIVP) in heart failure patients with CLBBB.MethodsTen patients prospectively underwent LBBAP (LBB‐CRT group) and 30 patients received BIVP (BIV‐CRT group) were matched using propensity score matching. LBBAP was achieved by the trans‐interventricular septum method. Echocardiography, electrocardiogram, NYHA classification, and blood B‐type natriuretic peptide concentration were evaluated at preimplantation and at 6‐month follow up. CRT response was defined as at least 15% decrease in left ventricular end‐systolic volume.ResultsIn the LBB‐CRT group, CLBBB were successfully corrected by LBBAP with no complications. QRS duration (QRSd) significantly decreased after implantation in both groups, and the decrease of QRSd in the LBB‐CRT group was significantly greater than that in the BIV‐CRT group (60.80 ± 20.09 vs. 33.00 ± 21.48 ms, p = .0009). The echocardiographic measurements including left ventricular end‐diastolic diameter, left ventricular end‐systolic diameter, and left ventricular ejection fraction significantly improved after 6 months in both groups. The response rate was significantly higher in LBB‐CRT group than BIV‐CRT group (100.00% vs. 63.33%, p = .038). The percentage of patients in New York Heart Association classification Grades I and II was significantly higher in the LBB‐CRT group compared with that in the BIV‐CRT group (median 1.5 vs. 2.0, p = .029) at 6‐month follow‐up.ConclusionsIt is effective and safe to correct CLBBB with LBBAP in heart failure patients. Compared with BIVP, LBBAP can better optimize electrical synchrony and improve cardiac function.

Patients with AF have abnormal electrophysiologic substrate in sinus rhythm characterized by lower mean bipolar voltage, more prevalent complex electrograms, and longer LA activation time. This substrate progresses parallel to progression of AF type.