BackgroundHis bundle pacing is a new method for delivering cardiac resynchronization therapy (CRT).ObjectivesThe authors performed a head-to-head, high-precision, acute crossover comparison between His bundle pacing and conventional biventricular CRT, measuring effects on ventricular activation and acute hemodynamic function.MethodsPatients with heart failure and left bundle branch block referred for conventional biventricular CRT were recruited. Using noninvasive epicardial electrocardiographic imaging, the authors identified patients in whom His bundle pacing shortened left ventricular activation time. In these patients, the authors compared the hemodynamic effects of His bundle pacing against biventricular pacing using a high-multiple repeated alternation protocol to minimize the effect of noise, as well as comparing effects on ventricular activation.ResultsIn 18 of 23 patients, left ventricular activation time was significantly shortened by His bundle pacing. Seventeen patients had a complete electromechanical dataset. In them, His bundle pacing was more effective at delivering ventricular resynchronization than biventricular pacing: greater reduction in QRS duration (−18.6 ms; 95% confidence interval [CI]: −31.6 to −5.7 ms; p = 0.007), left ventricular activation time (−26 ms; 95% CI: −41 to −21 ms; p = 0.002), and left ventricular dyssynchrony index (−11.2 ms; 95% CI: −16.8 to −5.6 ms; p < 0.001). His bundle pacing also produced a greater acute hemodynamic response (4.6 mm Hg; 95% CI: 0.2 to 9.1 mm Hg; p = 0.04). The incremental activation time reduction with His bundle pacing over biventricular pacing correlated with the incremental hemodynamic improvement with His bundle pacing over biventricular pacing (R = 0.70; p = 0.04).ConclusionsHis resynchronization delivers better ventricular resynchronization, and greater improvement in hemodynamic parameters, than biventricular pacing.

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Background— The optimal ablation strategy for persistent atrial fibrillation (AF) remains unclear. Methods and Results— This multicentre randomized study compared circumferential pulmonary vein ablation+linear ablation (control arm) versus circumferential pulmonary vein ablation+linear ablation+complex fractionated atrial electrogram (CFAE) ablation (CFAE arm) in patients with persistent AF. Circumferential pulmonary vein ablation was performed followed by roof and mitral isthmus ablation, before CFAE ablation in the CFAE arm. Ablation strategy was maintained at the first redo procedure. Sixty-five patients were recruited in each arm. The mean age was 61±10 years, 75% were men, median AF duration was 2 years, 42% had long-lasting persistent AF, 68% had associated cardiovascular disease, mean left atrial dimension was 46±6 mm, and median CHA 2 DS 2 -VASc score was 2. Ablation and procedure times were significantly longer in the CFAE arm (70±20 versus 55±17; 201±35 versus 152±45 minutes; P <0.005). After a mean follow-up of 35±5 months, single-procedural success off antiarrhythmic drugs at 12 months (CFAE: 30/65 [46%] versus control: 37/65 [57%]; P =0.29) and multiprocedural success (CFAE: 51/65 [78%] versus control: 52/65 [80%]; P =1.0) were not significantly different. At the first redo procedure, patients in the CFAE arm had a higher incidence of organized atrial tachycardia/flutter (24/33 [73%] versus 11/31 [35%]; P =0.005) and gap-related macro–re-entrant flutter (8/33[24%] versus 1/31[3%]; P =0.03). Early recurrence of atrial arrhythmia was an independent predictor of late recurrence. Conclusions— CFAE ablation did not confer incremental benefit when performed in addition to circumferential pulmonary vein ablation and linear ablation. It was associated with a higher incidence of gap-related flutter. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT01711047.